Updates

25-Sep-2022: sokol_app.h on Linux now optionally supports EGL instead of GLX for the window system glue code and can create a GLES2 or GLES3 context instead of a 'desktop GL' context. To get EGL+GLES2/GLES3, just define SOKOL_GLES2 or SOKOL_GLES3 to compile the implementation. To get EGL+GL, define SOKOL_GLCORE33 and SOKOL_FORCE_EGL. By default, defining just SOKOL_GLCORE33 uses GLX for the window system glue (just as before). Many thanks to GH user @billzez for the PR!
10-Sep-2022: sokol_app.h and sokol_args.h has been fixed for Emscripten 3.21, those headers used the Emscripten Javascript helper function ccall() which is now part of the 'legacy runtime' and causes linker errors. Instead of ccall() sokol_app.h and sokol_args.h now drop down to a lower level set of Emscripten JS helper functions (which hopefully won't go away anytime soon).
05-Aug-2022: New officially supported and automatically updated language bindings for Odin: https://github.com/floooh/sokol-odin (also see gen_odin.py)
10-Jul-2022: New features in sokol_app.h and sokol_imgui.h:
- In sokol_app.h it's now possible to set a mouse cursor type from a number of predefined types via the new function sapp_set_mouse_cursor(sapp_mouse_cursor cursor). The available cursor types are compatible with GLFW and Dear ImGui. Supported platforms are: macOS, linux, win32, uwp and web.
- sapp_show_mouse(bool shown) now also works on the web platform.
- In sokol_app.h, the poorly defined 'user cursor' feature has been removed (sapp_desc.user_cursor and SAPP_EVENTTYPE_UPDATE_CURSOR). This was a hack to allow changing the mouse cursor and only worked on Win32 and macOS (with different behaviour). Since setting the cursor type is now 'properly supported, this hack was removed.
- sokol_imgui.h will now set the cursor type via sapp_set_mouse_cursor(). This can be disabled with the new simgui_desc_t item disable_set_mouse_cursor.
- sokol_imgui.h now automatically enables resizing windows from edges (not just the bottom-right corner), this behavour can be disabled with the new simgui_desc_t item disable_windows_resize_from_edges.
- sokol_imgui.h can now optionally write to the alpha channel (useful if you want to render the UI into a separate render target, which is later composed onto the default framebuffer). The feature is enabled with the new simgui_desc_t item write_alpha_channel.
Many thanks to @tomc1998 for the initial Linux/X11 mouse cursor type PR and @luigi-rosso for the sokol_imgui.h alpha channel PR!
03-Jul-2022: A new sokol_gfx.h function bool sg_query_buffer_will_overflow(sg_buffer buf, size_t size) which allows to check if a call to sg_append_buffer() would overflow the buffer. This is an alternative to the sg_query_buffer_overflow() function which only reports the overflow after the fact. Many thanks to @RandyGaul for the PR!
29-Jun-2022: In sokol_app.h with the D3D11 backend, if SOKOL_DEBUG is defined, and the D3D11 device creation fails, there's now a fallback code path which tries to create the device again without the D3D11_CREATE_DEVICE_DEBUG flag. Turns out the D3D11 debug support may suddenly stop working (just happened to me, indicated by the Win10 "Graphics Tool" feature being silently uninstalled and failing to install when asked to do so). This fix at least allows sokol_app.h applications compiled in debug mode to run, even if the D3D11 debug layer doesn't work.
29-May-2022: The code generation scripts for the sokol-nim language bindings have been revised and updated, many thanks to Gustav Olsson for the PR! (I'm planning to spend a few more days integrating the bindings generation with Github Actions, so that it's easier to publish new bindings after updates to the sokol headers).
26-May-2022: The GL backend in sokol_app.h now allows to override the GL context version via two new items in the sapp_desc struct: sapp_desc.gl_major_version and sapp_desc.gl_minor_version. The default GL context version remains at 3.2. Overriding the GL version might make sense if you're not using sokol_app.h together with sokol_gfx.h, or otherwise want to call GL functions directly. Note that this only works for the 'desktop GL' backends (Windows, Linux and macOS), but not for the GLES backends (Android, iOS, web). Furthermore, on macOS only the GL versions 3.2 and 4.1 are available (plus the special config major=1 minor=0 creates an NSOpenGLProfileVersionLegacy context). In general: use at your risk :) Many thanks to Github user @pplux for the PR!
15-May-2022: The way internal memory allocation can be overridden with your own functions has been changed from global macros to callbacks provided in the API setup call. For instance in sokol_gfx.h:
```
void* my_malloc(size_t size, void* userdata) {
  (void)userdata; // unused
  return malloc(size);
}

void my_free(void* ptr, void* userdata) {
  (void)userdata; // unused
  free(ptr);
}

//...
  sg_setup(&(sg_desc){
    //...
    .allocator = {
      .alloc = my_malloc,
      .free = my_free,
      .user_data = ...,
    }
  });
```
sokol_gfx.h will now call my_malloc() and my_free() whenever it needs to allocate or free memory (note however that allocations inside OS functions or 3rd party libraries are not affected).

If no override functions are provided, the standard library functions malloc() and free() will be used, just as before.

This change breaks source compatibility in the following headers:
- sokol_fontstash.h: the function signature of sfons_create() has changed, this now takes a pointer to a new sfons_desc_t struct instead of individual parameters.
- sokol_gfx_imgui.h (NOT sokol_imgui.h!): likewise, the function signature of sg_imgui_init() has changed, this now takes an additional parameter which is a pointer to a new sg_imgui_desc_t struct.
All affected headers also have a preprocessor check for the outdated macros SOKOL_MALLOC, SOKOL_CALLOC and SOKOL_FREE and throw a compilation error if those macros are detected.

(if configuration through macros is still desired this could be added back in the future, but I figured that the new way is more flexible in most situations).

The header sokol_memtrack.h and the sample restart-sapp have been updated accordingly.

Also search for MEMORY ALLOCATION OVERRIDE in the header documentation block for more details.
14-May-2022: added a helper function simgui_map_keycode() to sokol_imgui.h to map sokol_app.h keycodes (sapp_keycode, SAPP_KEYCODE_*) to Dear ImGui keycodes (ImGuiKey, ImGuiKey_*). If you're using Dear ImGui function to check for key input, you'll need to update the code like this:
- Old:
```
ImGui::IsKeyPressed(SAPP_KEYCODE_A);
```
- New:
```
ImGui::IsKeyPressed(simgui_map_keycode(SAPP_KEYCODE_A));
```
This was basically 'fallout' from rewriting the input system in sokol_imgui.h to the new evented IO system in Dear ImGui.
08-Feb-2022: sokol_imgui.h has been updated for Dear ImGui 1.87:
- sokol_imgui.h's input code has been rewritten to use the new evented IO system and extended virtual key codes in Dear ImGui
- on non-Emscripten platforms, mouse buttons are no longer "cancelled" when the mouse leaves the window (since the native desktop platforms automatically capture the mouse when mouse buttons are pressed, but mouse capture is not supported in the sokol_app.h Emscripten backend)
28-Jan-2022: some window size behaviour changes in sokol_app.h.
- Asking for a default-sized window (via sapp_desc.width/height = 0) now behaves a bit differently on desktop platforms. Previously this set the window size to 640x480, now a default window covers more screen area:
  - on Windows CW_USEDEFAULT will be used for the size
  - on macOS and Linux, the window size will be 4/5 of the display size
  - no behaviour changes on other platforms
- On Windows and Linux, the window is now centered (in a later update, more control over the initial window position, and new functions for positioning and sizing might be provided)
- On Windows, when toggling between windowed and fullscreen, the window position and size will now be restored (on other platforms this already happened automatically through the window system)
- On all desktop platforms if an application starts in fullscreen and then is toggled back to windowed, the window will now be of the expected size (provided in sapp_desc.width/height)
20-Jan-2022:
- sokol_audio.h: A compatibility fix in the sokol_audio.h WASAPI backend (Windows): On some configs the IAudioClient::Initialize() call could fail because of a mismatch between the requested number of channels and speaker config. See #614 for details.
- sokol_app.h D3D11/DXGI: Fix an (uncritical) COM interface leak warning for IDXGIAdapter and IDXGIFactory at shutdown, introduced with the recent disabling of Alt-Enter.
18-Jan-2022:
- sokol_app.h now has per-monitor DPI support on Windows and macOS: when the application window is moved to a monitor with different DPI, the values returned by sapp_dpi_scale(), sapp_width() and sapp_height() will update accordingly (only if the application requested high-dpi rendering with sapp_desc.high_dpi=true, otherwise the dpi scale value remains fixed at 1.0f). The application will receive an SAPP_EVENTTYPE_RESIZED event if the default framebuffer size has changed because of a DPI change. On Windows this feature requires Win10 version 1703 or later (aka the 'Creators Update'), older Windows version simply behave as before. Many thank to @tjachmann for the initial PR with the Windows implementation!
- sokol_app.h: DPI scale computation on macOS is now more robust using the NSScreen.backingScaleFactor value
- sokol_app.h: the new frame timing code in sokol_app.h now detects if the display refresh rate changes and adjusts itself accordingly (for instance if the window is moved between displays with different refresh rate)
- sokol_app.h D3D11/DXGI: during window movement and resize, the frame is now presented with DXGI_PRESENT_DO_NOT_WAIT, this fixes some window system stuttering issues on Win10 configs with recent NVIDIA drivers.
- sokol_app.h D3D11/DXGI: the application will no longer appear to freeze for 0.5 seconds when the title bar is grabbed with the mouse for movement, but then not moving the mouse.
- sokol_app.h D3D11/DXGI: DXGI's automatic windowed/fullscreen switching via Alt-Enter has been disabled, because this switched to 'real' fullscreen mode, while sokol_app.h's fullscreen mode uses a borderless window. Use the programmatic fullscreen/window switching via sapp_toggle_fullscreen() instead.
- BREAKING CHANGE in sokol_imgui.h: because the applications' DPI scale can now change at any time, the DPI scale value is now communicated to sokol_imgui.h in the simgui_new_frame() function. This has been changed to accept a pointer to a new simgui_frame_desc_t struct. With C99, change the simgui_new_frame() call as follows (if also using sokol_app.h):
```
simgui_new_frame(&(simgui_frame_desc_t){
    .width = sapp_width(),
    .height = sapp_height(),
    .delta_time = sapp_frame_duration(),
    .dpi_scale = sapp_dpi_scale()
});
```
  On C++ this works:
```
simgui_new_frame({ sapp_width(), sapp_height(), sapp_frame_duration(), sapp_dpi_scale() });
```
  ...or in C++20:
```
simgui_new_frame({
    .width = sapp_width(),
    .height = sapp_height(),
    .delta_time = sapp_frame_duration(),
    .dpi_scale = sapp_dpi_scale()
});
```
- KNOWN ISSUE: the recent change in sokol-audio's WASAPI backend to directly consume float samples doesn't appear to work on some configs (see #614), investigation is underway
15-Jan-2022:
- A bugfix in the GL backend for uniform arrays using the 'native' uniform block layout. The bug was a regression in the recent 'uniform data handling' update. See PR #611 for details, and this new sample/test. Many thanks to @nmr8acme for the PR!
08-Jan-2022: some enhancements and cleanup to uniform data handling in sokol_gfx.h and the sokol-shdc shader compiler:
- IMPORTANT: when updating sokol_gfx.h (and you're using the sokol-shdc shader compiler), don't forget to update the sokol-shdc binaries too!
- The GLSL uniform types int, ivec2, ivec3 and ivec4 can now be used in shader code, those are exposed to the GL backends with the new sg_uniform_type items SG_UNIFORM_TYPE_INT[2,3,4].
- A new enum sg_uniform_layout, currently with the values SG_UNIFORMLAYOUT_NATIVE and SG_UNIFORMLAYOUT_STD140. The enum is used in sg_shader_uniform_block_desc as a 'packing rule hint', so that the GL backend can properly locate the offset of uniform block members. The default (SG_UNIFORMLAYOUT_NATIVE) keeps the same behaviour, so existing code shouldn't need to be changed. With the packing rule SG_UNIFORMLAYOUT_STD140 the uniform block interior is expected to be layed out according to the OpenGL std140 packing rule.
- Note that the SG_UNIFORMLAYOUT_STD140 only allows a subset of the actual std140 packing rule: arrays are only allowed for the types vec4, int4 and mat4. This is because the uniform data must still be compatible with glUniform() calls in the GL backends (which have different 'interior alignment' for arrays).
- The sokol-shdc compiler supports the new uniform types and will annotate the code-generated sg_shader_desc structs with SG_UNIFORMLAYOUT_STD140, and there are new errors to make sure that uniform blocks are compatible with all sokol_gfx.h backends.
- Likewise, sokol_gfx.h has tighter validation for the sg_shader_uniform_block desc struct, but only when the GL backend is used (in general, the interior layout of uniform blocks is only relevant for GL backends, on all other backends sokol_gfx.h just passes the uniform data as an opaque block to the shader) For more details see:
- new sections in the sokol_gfx.h documentation
- documentation of sg_uniform_layout
- enhanced sokol-shdc documentation
- a new sample 'uniformtypes-sapp'
PS: and an unrelated change: the frame latency on Win32+D3D11 has been slightly improved via IDXGIDevice1::SetMaximumFrameLatency()
27-Dec-2021: sokol_app.h frame timing improvements:
- A new function double sapp_frame_duration(void) which returns the frame duration in seconds, averaged over the last 256 frames to smooth out jittering spikes. If available, this uses platform/backend specific functions of the swapchain API:
  - On Windows: DXGI's GetFrameStatistics().SyncQPCTime.
  - On Emscripten: the timestamp provided by the RAF callback, this will still be clamped and jittered on some browsers, but averaged over a number of frames yields a pretty accurate approximation of the actual frame duration.
  - On Metal, MTLDrawable addPresentedHandler + presentedTime doesn't appear to function correctly on macOS Monterey and/or M1 Macs, so instead mach_absolute_time() is called at the start of the MTKView frame callback.
  - In all other situations, the same timing method is used as in sokol_time.h.
- On macOS and iOS, sokol_app.h now queries the maximum display refresh rate of the main display and uses this as base to compute the preferred frame rate (by multiplying with sapp_desc.swap_interval), previously the preferred frame rate was hardwired to 60 * swap_interval. This means that native macOS and iOS applications may now run at 120Hz instead of 60Hz depending on the device (I realize that this isn't ideal, there will probably be a different way to hint the preferred interval at which the frame callback is called, which would also support disabling vsync and probably also adaptive vsync).
19-Dec-2021: some sokol_audio.h changes:
- on Windows, sokol_audio.h no longer converts audio samples from float to int16_t, but instead configures WASAPI to directly accept float samples. Many thanks to github user iOrange for the PR!
- sokol_audio.h has a new public function saudio_suspended() which returns true if the audio device/context is currently in suspended mode. On all backends except WebAudio this always returns false. This allows to show a visual hint to the user that audio is muted until the first input event is received.
18-Dec-2021: the sokol_gfx.h sg_draw() function now uses the currently applied pipeline object to decide if the GL or D3D11 backend's instanced drawing function should be called instead of the num_instances argument. This fixes a bug on some WebGL configs when instanced rendering is configured but sg_draw() is called with an instance count of 1.
18-Nov-2021: sokol_gl.h has a new function to control the point size for point list rendering: void sgl_point_size(float size). Note that on D3D11 the point size is currently ignored (since D3D11 doesn't support a point size at all, the feature will need to be emulated in sokol_gl.h when the D3D11 backend is active). Also note that points cannot currently be textured, only colored.
08-Oct-2021: texture compression support in sokol_gfx.h has been revisited:
- tighter validation checks on texture creation:
  - content data validation now also happens in sg_make_image() (previously only in sg_update_image())
  - validate that compressed textures are immutable
  - separate "no data" validation checks for immutable vs dynamic/stream textures
  - provided data size for creating or updating textures must match the expected surface sizes exactly
- fix PVRTC row and surface pitch computation according to the GL PVRTC extension spec
- better adhere to Metal documentation for the MTLTexture.replaceRegion parameters (when bytesPerImage is expected to be zero or not)
02-Sep-2021: some minor non-breaking additions:
- sokol_app.h: new events FOCUSED and UNFOCUSED to indicate that the window has gained or lost the focused state (Win32: WM_SETFOCUS/WM_KILLFOCUS, macOS: windowDidBecomeKey/windowDidResignKey, X11: FocusIn/FocusOut, HTML5: focus/blur).
- sokol_app.h Emscripten backend: the input event keycode is now extracted from the HTML5 code string which yields the actual unmapped virtual key code.
21-Aug-2021: some minor API tweaks in sokol_gl.h and sokol_debugtext.h, one of them breaking (still minor though):
- sokol_gl.h has a new function sgl_default_context() which returns the default context handle, it's the same as the global constant SGL_DEFAULT_CONTEXT, but wrapping this in a function is better for language bindings
- ...and a similar function in sokol_debugtext.h: sdtx_default_context()
- The sokol_gl.h function sgl_default_pipeline() has been renamed to sgl_load_default_pipeline(). This fits better with the related function sgl_load_pipeline() and doesn't 'semantically clash' with the new function sgl_default_context(). The sgl_default_pipeline() function is rarely used, so it's quite unlikely that this change breaks your code.
19-Aug-2021: sokol_gl.h gained rendering context support, this allows sokol-gl to render into different sokol-gfx render passes. No changes are needed for existing sokol-gl code. Check the updated header documentation and the new sample sgl-context-sapp for details!
21-Jun-2021: A new utility header sokol_color.h has been added, which adds sokol_gfx.h-compatible named color constants and a handful initial utility functions. See the header documentation for details. Many thanks to Stuart Adams (@nyalloc) for contributing the header!
12-Apr-2021: Minor new feature in sokol_app.h: mouse buttons are now also reported as modifier flags in most input events (similar to the Ctrl-, Alt-, Shift- and Super-key modifiers). This lets you quickly check what mouse buttons are currently pressed in any input event without having to keep track of pressed mouse buttons yourself. This is implemented in the following sokol_app.h backends: Win32, UWP, Emscripten, X11 and macOS. Example code is in the events-sapp.cc sample
10-Apr-2021: followup fixes from yesterday: custom icon support on macOS has been added (since macOS has no regular window icons, the dock icon is updated instead), and a bugfix in the internal helper which select the best matching candidate image (this actually always selected the first candidate image)
09-Apr-2021: sokol_app.h now allows to programmatically set the window icon in the Win32, X11 and HTML5 backends. Search for "WINDOW ICON SUPPORT" in sokol_app.h for documentation, and see the new icon sample for example code.
01-Apr-2021: some fixes in sokol_app.h's iOS backend:
- In the iOS Metal backend, high-dpi vs low-dpi works again. Some time ago (around iOS 12.x) MTKView started to ignore the contentScaleFactor property, which lead to sokol_app.h always setting up a HighDPI framebuffer even when sapp_desc.high_dpi wasn't set. The fix is to set the MTKView's drawableSize explicitely now.
- The iOS GL backend didn't support MSAA multisampling so far, this has been fixed now, but only one MSAA mode (4x) is available, which will be selected when sapp_desc.sample_count is greater than 1.
31-Mar-2021: sokol_audio.h on macOS no longer includes system framework headers (AudioToolbox/AudioToolbox.h), instead the necessary declarations are embedded directly in sokol_audio.h (to get the old behaviour and force inclusion of AudioToolbox/AudioToolbox.h, define SAUDIO_OSX_USE_SYSTEM_HEADERS before including the sokol_audio.h implementation). This "fix" is both an experiment and an immediate workaround for a current issue in Zig's HEAD version (what will eventually become zig 0.8.0). See this issue for details: ziglang/zig#8360). The experiment is basically to see whether this approach generally makes sense (replacing system headers with embedded declarations, so that the sokol headers only depend on C standard library headers). This approach might simplify cross-compilation and integration with other languages than C and C++.
20-Mar-2021: The Windows-specific OpenGL loader, and the platform-specific GL header includes have been moved from sokol_app.h to sokol_gfx.h. This means:
- In general, the sokol_gfx.h implementation can now simply be included without having to include other headers which provide the GL API declarations first (e.g. when sokol_gfx.h is used without sokol_app.h, you don't need to use a GL loader, or include the system-specific GL headers yourself).
- When sokol_gfx.h is used together with sokol_app.h, the include order for the implementations doesn't matter anymore (until now, the sokol_app.h implementation had to be included before the sokol_gfx.h implementation).
- The only "downside" (not really a downside) is that sokol_gfx.h now has platform detection ifdefs to include the correct GL headers for a given platform. Until now this problem was "delegated" to the library user.
- The old macro SOKOL_WIN32_NO_GL_LOADER has been removed, and replaced with a more general SOKOL_EXTERNAL_GL_LOADER. Define this before including the sokol_gfx.h implementation if you are using your own GL loader or provide the GL API declarations in any other way. In this case, sokol_gfx.h will not include any platform GL headers, and the embedded Win32 GL loader will be disabled.
22-Feb-2021: Mouse input latency in sokol_app.h's macOS backend has been quite significantly reduced, please see the detailed explanation in this PR. Many thanks to @randrew for the PR!
19-Feb-2021: sokol_app.h learned some Windows-specific config options to redirect stdout/stderr to the parent terminal or a separate console window, and allow outputting UTF-8 encoded text. For details, search for "WINDOWS CONSOLE OUTPUT" in sokol_app.h. Many thanks to @garettbass for the initial PR!
17-Feb-2021: When compiled for iOS, the sokol_audio.h CoreAudio backend now uses the AVAudioSession class to activate and deactivate audio output as needed. This fixes sokol_audio.h for iPhones (so far, sokol_audio.h accidentally only worked for iPads). Please see this issue for details. A somewhat unfortunate side effect of this fix is that sokol_audio.h must now be compiled as Objective-C when targetting iOS, also note that a new framework must be linked: AVFoundation. Many thanks to @oviano for providing the PR!
14-Feb-2021: The Dear ImGui rendering backend in sokol_imgui.h has been rewritten to only do a single buffer-update per frame each for vertex- and index-data. This addresses performance-problems with sg_append_buffer() in the GL backend on some platforms (see this issue for details.
13-Feb-2021: A new utility header sokol_nuklear.h has been added which implements a rendering backend for Nuklear on top of sokol_gfx.h. Also see the new sample nuklear-sapp. Many thanks to @wmerrifield for the PR!
10-Feb-2021: The breaking API-update has been merged (mainly sokol_gfx.h). Please see this blogpost and the updates sokol samples for details. I also created a git tag named 'pre-feb2021-api-changes' which captures the previous state in all related projects. Please also update the sokol-tools-bin if you're using the sokol-shdc shader compiler.
07-Feb-2021: A PSA about upcoming breaking changes in (mainly) sokol_gfx.h: https://floooh.github.io/2021/02/07/sokol-api-overhaul.html
20-Dec-2020: A couple of minor breaking changes in the sokol_gfx.h and sokol_app.h APIs as preparation for the upcoming automatic language binding generation:
- in sokol_gfx.h nested unions have been removed:
  - sg_image_desc.depth/.layers has been renamed to .num_slices
  - sg_attachment_desc.face/.layer/.slice has been unified to .slice
- in sokol_app.h the return value of sapp_run() has been changed from int to void (the function always returned zero anyway)
Non-breaking (or at most potentially breaking) changes:
- expressions in enums have been replaced with integer literals (e.g. (1<<2) becomes 4)
- the value of SAPP_MOUSEBUTTON_INVALID has been changed from -1 to 0x100
For more information about the upcoming automatic language-bindings generation see this bog post
02-Dec-2020: sokol_gfx.h has a couple new public API functions for destroying resources in two steps:
- sg_uninit_buffer + sg_dealloc_buffer
- sg_uninit_image + sg_dealloc_image
- sg_uninit_shader + sg_dealloc_shader
- sg_uninit_pipeline + sg_dealloc_pipeline
- sg_uninit_pass + sg_dealloc_pass
Calling both functions in this order is identical with calling the traditional sg_destroy_xxx() functions. See this PR for more details: floooh#435. Many thanks to @oviano for the PR!
28-Nov-2020: In addition to the generic SOKOL_API_DECL and SOKOL_IMPL defines there are now header-specific versions SOKOL_xxx_API_DECL and SOKOL_xxx_IMPL (for instance SOKOL_GFX_API_DECL and SOKOL_GFX_IMPL). The original motivation for splitting the SOKOL_API_DECL defines up is described here: floooh#428). The same change for SOKOL_IMPL also finally unifies the approach used in the utility headers (in the util subdirectory), which exclusively used the SOKOL_xxx_IMPL pattern with the core headers which exclusively used SOKOL_IMPL before (all headers accept both patterns now). Many thanks to @iboB for providing the API_DECL PR!
17-Nov-2020: A new utility header sokol_shape.h to generate vertices+indices for simple shapes (plane, box, sphere, cylinder and torus), which seamlessly plug into the sokol_gfx.h resource creation functions. As with most new utility headers, the initial functionality is a bit bare bones and the public API shouldn't be considered stable yet. Check the sokol-samples webpage for new and updates samples: https://floooh.github.io/sokol-html5/
08-Nov-2020 PSA: It appears that RenderDoc v1.10 chokes on the new D3D11/DXGI swapchain code from 10-Oct-2020 in sokol_app.h. The current RenderDoc Nightly Build works, so I guess in v1.11 everything will be fine.
03-Nov-2020: sokol_app.h: the missing drag'n'drop support for HTML5/WASM has been added. This adds two platform-specific functions sapp_html5_get_dropped_file_size() and sapp_html5_fetch_dropped_file(). Please read the documentation section in sokol_app.h under 'DRAG AND DROP SUPPORT' for additional details and example code. Also consult the source code of the new droptest-sapp sample for an example of how to load the content of dropped files on the web and native platforms:

https://floooh.github.io/sokol-html5/droptest-sapp.html
27-Oct-2020: I committed a bugfix for a longstanding WebGL canvas id versus css-selector confusion in the emscripten/WASM backend code in sokol_app.h. I think the fix should not require any changes in your code (because if you'd be using a canvas name different from the default "canvas" it wouldn't have worked before anyway). See this bug for details: floooh#407
22-Oct-2020: sokol_app.h now has file drag'n'drop support on Win32, macOS and Linux. WASM/HTML5 support will be added soon-ish. This will work a bit differently because of security-related restrictions in the HTML5 drag'n'drop API, but more on that later. For documentation, search for 'DRAG AND DROP SUPPORT' in sokol_app.h.

Check out events-sapp.c for a simple usage example (I will also add a more real-world example to my chips emulators once the WASM/HTML5 implementation is ready).

Many thanks for @prime31 and @hb3p8 for the initial PRs and valuable feature discussions!
10-Oct-2020: Improvements to the sokol_app.h Win32+D3D11 and UWP+D3D11 swapchain code:
- In the Win32+D3D11 backend and when running on Win10, DXGI_SWAP_EFFECT_FLIP_DISCARD is now used. This gets rid of a deprecation warning in the debugger console and also should allow slightly more efficient swaps in some situations. When running on Win7 or Win8, the traditional DXGI_SWAP_EFFECT_DISCARD is used.
- The UWP backend now supports MSAA multisampling (the required fixes for this are the same as in the Win32 backend with the new swap effect: a separate MSAA texture and render-target-view is created where rendering goes into, and this MSAA texture is resolved into the actual swapchain surface before presentation).
07-Oct-2020: A fix in the ALSA/Linux backend initialization in sokol_audio.h: Previously, initialization would fail if ALSA can't allocate the exact requested buffer size. Instead sokol_audio.h let's now pick ALSA a suitable buffer size. Also better log messages in the ALSA initialization code if something goes wrong. Unfortunately I'm not able to reproduce the buffer allocation problem on my Linux machine. Details are in this issue: floooh#400

NARRATOR: the fix didn't work.
02-Oct-2020: The sokol_app.h Win32 backend can now render while moving and resizing the window. NOTE that resizing the swapchain buffers (and receiving SAPP_EVENTTYPE_RESIZED events) is deferred until the resizing finished. Resizing the swapchain buffers each frame created a substantial temporary memory spike of up to several hundred MBytes. I need to figure out a better swapchain resizing strategy.
30-Sep-2020: sokol_audio.h now works on UWP, thanks again to Alberto Fustinoni (@albertofustinoni) for the PR!
26-Sep-2020: sokol_app.h gained a new function sapp_set_window_title() to change the window title on Windows, macOS and Linux. Many thanks to @medvednikov for the initial PR!
23-Sep-2020: sokol_app.h now has initial UWP support using the C++/WinRT set of APIs. Currently this requires "bleeding edge" tools: A recent VS2019 version, and a very recent Windows SDK version (at least version 10.0.19041.0). Furthermore the sokol_app.h implementation must be compiled as C++17 (this is a requirement of the C++/WinRT headers). Note that the Win32 backend will remain the primary and recommended backend on Windows. The UWP backend should only be used when the Win32 backend is not an option. The sokol-samples project has two new build configs sapp-uwp-vstudio-debug and sapp-uwp-vstudio-release to build the sokol-app samples for UWP.

Many thanks to Alberto Fustinoni (@albertofustinoni) for providing the initial PR!

(also NOTE: UWP-related fixes in other sokol headers will follow)
22-Sep-2020: A small fix in sokol_app.h's Win32 backend: when a mouse button is pressed, mouse input is now 'captured' by calling SetCapture(), and when the last mouse button is released, ReleaseCapture() is called. This also provides mouse events outside the window area as long as a mouse button is pressed, which is useful for windowed UI applicactions (this is not the same as the more 'rigorous' and explicit pointer-lock feature which is more useful for camera-controls)
31-Aug-2020: Internal change: The D3D11/DXGI backend code in sokol_gfx.h and sokol_app.h now use the D3D11 and DXGI C++-APIs when the implementation is compiled as C++, and the C-APIs when the implementation is compiled as C (before, the C API was also used when the implementation is compiled as C++). The new behaviour is useful when another header must use the D3D11/DXGI C++ APIs but should be included in the same compilation unit as sokol_gfx.h an sokol_app.h (for example see this PR: floooh#351).
24-Aug-2020: The backend-specific callback functions that are provided to sokol_gfx.h in the sg_setup() initialization call now have alternative versions which accept a userdata-pointer argument. The userdata-free functions still exist, so no changes are required for existing code.
02-Aug-2020:
- sokol_app.h now has a mouse-lock feature (aka pointer-lock) via two new functions void sapp_lock_mouse(bool lock) and bool sapp_mouse_locked(void). For documentation, please search for 'MOUSE LOCK' in sokol_app.h. The sokol-app samples events-sapp and cgltf-sapp have been updated to demonstrate the feature.
- sokol_app.h Linux: mouse pointer visibility (via void sapp_show_mouse(bool show)) has been implemented for Linux/X11
- sokol_app.h WASM: mouse wheel scroll deltas are now 'normalized' between the different scroll modes (pixels, lines, pages). See this issue: floooh#339. Many thanks to @bqqbarbhg for investigating the issue and providing a solution!
- sokol_app.h now has better documentation what system libraries must be linked on the various platforms (and on Linux two additional libraries must be linked now: Xcursor and Xi)
22-Jul-2020: PLEASE NOTE cmake 3.18 breaks some of sokol samples when compiling with the Visual Studio toolchain because some C files now actually compile as C++ for some reason (see: https://twitter.com/FlohOfWoe/status/1285996526117040128). Until this is fixed, or I have come up with a workaround, please use an older cmake version to build the sokol samples with the Visual Studio compiler.

(Update: I have added a workaround to fips: https://github.com/floooh/fips/commit/89997b8ebdca6fc9455a5cfe6145eecaa017df49 which fixes the issue at least for fips projects)
14-Jul-2020:
- sapp_mouse_shown() has been implemented for macOS (thanks to @slmjkdbtl for providing the initial PR!)
- On macOS, the lower-level functions CGDisplayShowCursor and CGDisplayHideCursor are now used instead of the NSCursor class. This is in preparation for the 'pointer lock' feature which will also use CGDisplay* functions.
- Calling sapp_show_mouse(bool visible) no longer 'stacks' (e.g. there's no 'hidden counter' underneath anymore, instead calling sapp_show_mouse(true) will always show the cursor and sapp_show_mouse(false) will always hide it. This is a different behaviour than the underlying Win32 and macOS functions ShowCursor() and CGDisplaShow/HideCursor()
- The mouse show/hide behaviour can now be tested in the events-sapp sample (so far this only works on Windows and macOS).
13-Jul-2020:
- On macOS and iOS, sokol_app.h and sokol_gfx.h can now be compiled with ARC (Automatic Reference Counting) disabled (previously ARC had to be enabled).
- Compiling with ARC enabled is still supported but with a little caveat: if you're compiling sokol_app.h or sokol_gfx.h in ObjC mode (not ObjC++ mode) AND ARC is enabled, then the Xcode version must be more recent than before (the language feature __has_feature(objc_arc_fields) must be supported, which I think has been added in Xcode 10.2, I couldn't find this mentioned in any Xcode release notes though). Compiling with ARC disabled should also work on older Xcode versions though.
- Various internal code cleanup things:
  - sokol_app.h had the same 'structural cleanup' as sokol_gfx.h in January, all internal state (including ObjC id's) has been merged into a single big state structure. Backend specific struct declarations have been moved closer together in the header, and backend-specific structures and functions have been named more consistently for better 'searchability'
  - The 'mini GL' loader in the sokol_app.h Win32+WGL backend has been rewritten to use X-Macros (less redundant lines of code)
  - All macOS and iOS code has been revised and cleaned up
  - On macOS a workaround for a (what looks like) post-Catalina NSOpenGLView issue has been added: if the sokol_app.h window doesn't fit on screen (and was thus 'clamped' by Cocoa) AND the content-size was not set to native Retina resolution, the initial content size was reported as if it was in Retina resolution. This caused an empty screen to be rendered in the imgui-sapp demo. The workaround is to hook into the NSOpenGLView reshape event at which point the reported content size is correct.
  - On macOS and iOS, the various 'view delegate' objects have been removed, and rendering happens instead in the subclasses of MTKView, GLKView and NSOpenGLView.
  - On macOS and iOS, there's now proper cleanup code in the applicationWillTerminate callback (although note that on iOS this function isn't guaranteed to be called, because an application can also simply be killed by the operating system.
22-Jun-2020: The X11/GLX backend in sokol_app.h now has (soft-)fullscreen support, bringing the feature on par with Windows and macOS. Many thanks to @medvednikov for the PR!
20-Jun-2020: Some work to better support older DX10-level GPUs in the sokol_gfx.h D3D11 backend:
- sg_make_shader() now by default compiles HLSL shader code as shader model 4.0 (previously shader model 5.0 which caused problems with some older Intel GPUs still in use, see this issue: floooh#179)
- A new string item const char* d3d11_target in sg_shader_stage_desc now allows to pass in the D3D shader model for compiling shaders. This defaults to "vs_4_0" for the vertex shader stage and "ps_4_0" for the fragment shader stage. The minimal DX shader model for use with the sokol_gfx.h D3D11 backend is shader model 4.0, because that's the first shader model supporting constant buffers.
- The sokol-shdc shader compiler tool has a new output option hlsl4 to generate HLSL4 source code and shader model 4.0 byte code.
- All embedded D3D shader byte code in the sokol utility headers has been changed from shader model 5.0 to 4.0
If you are using sokol_gfx.h with sokol-shdc, please update both at the same time to avoid compilation errors caused by the new sg_shader_stage_desc.d3d11_target item. The sg_shader_desc initialization code in sokol-shdc has now been made more robust to prevent similar problems in the future.
14-Jun-2020: I have added a very simple utility header sokol_memtrack.h which allows to track memory allocations in sokol headers (number and overall size of allocations) by overriding the macros SOKOL_MALLOC, SOKOL_CALLOC and SOKOL_FREE. Simply include sokol_memtrack.h before the other sokol header implementation includes to enable memory tracking in those headers (but remember that the sokol_memtrack.h implementation must only be included once in the whole project, so this only works when all other sokol header implementations are included in the same compilation unit).
06-Jun-2020: Some optimizations in the sokol_gfx.h GL backend to avoid redundant GL calls in two areas: in the sg_begin_pass() calls when not clearing the color- and depth-stencil-attachments, and in sg_apply_bindings() when binding textures. Everything should behave exactly as before, but if you notice any problems in those areas, please file a bug. Many thanks to @edubart for the PRs!
01-Jun-2020: sokol_app.h now allows to toggle to and from fullscreen programmatically and to query the current fullscreen state via 2 new functions: sapp_toggle_fullscreen() and sapp_is_fullscreen(). Currently this is only implemented for Windows and macOS (not Linux). Thanks to @mattiasljungstrom for getting the feature started and providing the Win32 implementation!
28-May-2020: a small quality-of-life improvement for C++ coders: when the sokol headers are included into C++, all public API functions which take a pointer to a struct now have a C++ overload which instead takes a const-ref. This allows to move the struct initialization right into the function call just like in C99. For instance, in C99 one can write:
```
sg_buffer buf = sg_make_buffer(&(sg_buffer_desc){
    .size = sizeof(vertices),
    .type = SG_BUFFERTYPE_VERTEXBUFFER,
    .content = vertices
});
```
In C++ it isn't possible to take the address of an 'adhoc-initialized' struct like this, but with the new reference-wrapper functions (and C++20 designated initialization) this should work now:
```
sg_buffer buf = sg_make_buffer({
    .size = sizeof(vertices),
    .type = SG_BUFFERTYPE_VERTEXBUFFER,
    .content = vertices
});
```
Many thanks to @garettbass for providing the PR!
27-May-2020: a new utility header sokol_debugtext.h for rendering simple ASCII text using vintage home computer fonts via sokol_gfx.h
13-May-2020: a new function in sokol_time.h to round a measured frame time to common display refresh rates: stm_round_to_common_refresh_rate(). See the header documentation for the motivation behind this function.
02-May-2020: sokol_app.h: the 'programmatic quit' behaviour on the web-platform is now more in line with other platforms: calling sapp_quit() will invoke the cleanup callback function, perform platform-specific cleanup (like unregistering JS event handlers), and finally exit the frame loop. In typical scenarios this isn't very useful (because usually the user will simply close the tab, which doesn't allow to run cleanup code), but it's useful for situations where the same code needs to run repeatedly on a web page. Many thanks to @caiiiycuk for providing the PR!
30-Apr-2020: experimental WebGPU backend and a minor breaking change:
- sokol_gfx.h: a new WebGPU backend, expect frequent breakage for a while because the WebGPU API is still in flux
- a new header sokol_glue.h, with interop helper functions when specific combinations of sokol headers are used together
- changes in the way sokol_gfx.h is initialized via a new layout of the sg_desc structure
- sokol_gfx.h: a new sg_sampler_type enum which is required for shader creation to tell the WebGPU backend about the sampler data types (float, signed int, or unsigned int) used in the shader
- sokol_app.h: a handful new functions to query default framebuffer attributes (color- and depth-buffer pixel formats, and MSAA sample count)
- sokol_app.h: WebGPU device and swapchain initialization (currently only in the emscripten code path)
- sokol-shdc has been updated with WebGPU support (currently outputs SPIRV bytecode), and to output the new sg_sampler_type enum in sg_shader_image_desc
- sokol-samples has a new set of backend-specific WebGPU samples, and the other samples have been updated for the new sokol-gfx initialization
- pre-webgpu tags have been added to the sokol, sokol-samples, sokol-tools and sokol-tools-bin github repositories (in case you need to continue working with the older versions)
- please see this blog post for more details
05-Apr-2020: A bugfix in sokol_gl.h, the (fairly recent) optimization for merging draw calls contained a bug that could be triggered in an "empty" sgl_begin/sgl_end pair (with no vertices recorded inbetween). This could lead to the following draw call being rendered with the wrong uniform data.
30-Jan-2020: Some cleanup in sokol_gfx.h in the backend implementation code, internal data structures and documentation comments. The public API hasn't changed, so the change should be completely invisible from the outside.
02-Dec-2019: Initial clipboard support in sokol_app.h for Windows, macOS and HTML5. This allows to read and write UTF-8 encoded strings from and to the target platform's shared clipboard.

A 'real-world' example usage is in the Visual6502 Remix project.

Unfortunately clipboard support on the HTML5 platform comes with a lot of platform-specific caveats which can't be solved in sokol_app.h alone because of the restrictions the web platform puts on clipboard access and different behaviours and support levels of the various HTML5 clipboard APIs. I'm not really happy with the current HTML5 clipboard implementation. It sorta works, but it sure ain't pretty :)

Maybe the situation will improve in a few years when all browsers agree on and support the new permission-based clipboard API.

For documentation of the clipboard feature, search for CLIPBOARD SUPPORT in sokol_app.h
08-Sep-2019: sokol_gfx.h now supports clamp-to-border texture sampling:
- the enum sg_wrap has a new member SG_WRAP_CLAMP_TO_BORDER
- there's a new enum sg_border_color
- the struct sg_image_desc has a new member sg_border_color border_color
- new feature flag in sg_features: image_clamp_to_border
Note the following caveats:
- clamp-to-border is only supported on a subset of platforms, support can be checked at runtime via sg_query_features().image_clamp_to_border (D3D11, desktop-GL and macOS-Metal support clamp-to-border, all other platforms don't)
- there are three hardwired border colors: transparent-black, opaque-black and opaque-white (modern 3D APIs have moved away from a freely programmable border color)
- if clamp-to-border is not supported, sampling will fall back to clamp-to-edge without a validation warning
Many thanks to @martincohen for suggesting the feature and providing the initial D3D11 implementation!
31-Aug-2019: The header sokol_gfx_cimgui.h has been merged into sokol_gfx_imgui.h. Same idea as merging sokol_cimgui.h into sokol_imgui.h, the implementation is now "bilingual", and can either be included into a C++ file or into a C file. When included into a C++ file, the Dear ImGui C++ API will be called directly, otherwise the C API bindings via cimgui.h
28-Aug-2019: The header sokol_cimgui.h has been merged into sokol_imgui.h. The sokol_cimgui.h header had been created to implement Dear ImGui UIs from pure C applications, instead of having to fall back to C++ just for the UI code. However, there was a lot of code duplication between sokol_imgui.h and sokol_cimgui.h, so that it made more sense to merge the two headers. The C vs C++ code path will be selected automatically: When the implementation of sokol_imgui.h is included into a C++ source file, the Dear ImGui C++ API will be used. Otherwise, when the implementation is included into a C source file, the C API via cimgui.h
27-Aug-2019: sokol_audio.h now has an OpenSLES backend for Android. Many thanks to Sepehr Taghdisian (@septag) for the PR!
26-Aug-2019: new utility header for text rendering, and fixes in sokol_gl.h:
- a new utility header sokol_fontstash.h which implements a renderer for fontstash.h on top of sokol_gl.h
- sokol_gl.h updates:
  - Optimization: If no relevant state between two begin/end pairs has changed, draw commands will be merged into a single sokol-gfx draw call. This is especially useful for text- and sprite-rendering (previously, each begin/end pair would always result in one draw call).
  - Bugfix: When calling sgl_disable_texture() the previously active texture would still remain active which could lead to rendering artefacts. This has been fixed.
  - Feature: It's now possible to provide a custom shader in the 'desc' argument of sgl_make_pipeline(), as long as the shader is "compatible" with sokol_gl.h, see the sokol_fontstash.h header for an example. This feature isn't "advertised" in the sokol_gl.h documentation because it's a bit brittle (for instance if sokol_gl.h updates uniform block structures, custom shaders would break), but it may still come in handy in some situations.
20-Aug-2019: sokol_gfx.h has a couple new query functions to inspect the default values of resource-creation desc structures:
```
sg_buffer_desc sg_query_buffer_defaults(const sg_buffer_desc* desc);
sg_image_desc sg_query_image_defaults(const sg_image_desc* desc);
sg_shader_desc sg_query_shader_defaults(const sg_shader_desc* desc);
sg_pipeline_desc sg_query_pipeline_defaults(const sg_pipeline_desc* desc);
sg_pass_desc sg_query_pass_defaults(const sg_pass_desc* desc);
```
These functions take a pointer to a resource creation desc struct that may contain zero-initialized values (to indicate default values) and return a new struct where the zero-init values have been replaced with concrete values. This is useful to inspect the actual creation attributes of a resource.
18-Aug-2019:
- Pixelformat and runtime capabilities modernization in sokol_gfx.h (breaking changes):
  - The list of pixel formats supported in sokol_gfx.h has been modernized, many new formats are available, and some formats have been removed. The supported pixel formats are now identical with what WebGPU provides, minus the SRGB formats (if SRGB conversion is needed it should be done in the pixel shader)
  - The pixel format list is now more "orthogonal":
    - one, two or four color components (R, RG, RGBA)
    - 8-, 16- or 32-bit component width
    - unsigned-normalized (no postfix), signed-normalized (SN postfix), unsigned-integer (UI postfix) and signed-integer (SI postfix) and float (F postfix) component types.
    - special pixel formats BGRA8 (default render target format on Metal and D3D11), RGB10A2 and RG11B10F
    - DXT compressed formats replaced with BC1 to BC7 (BC1 to BC3 are identical to the old DXT pixel formats)
    - packed 16-bit formats (like RGBA4) have been removed
    - packed 24-bit formats (RGB8) have been removed
  - Use the new function sg_query_pixelformat() to get detailed runtime capability information about a pixelformat (for instance whether it is supported at all, can be used as render target etc...).
  - Use the new function sg_query_limits() to query "numeric limits" like maximum texture dimensions for different texture types.
  - The enumeration sg_feature and the function sg_query_feature() has been replaced with the new function sg_query_features(), which returns a struct sg_features (this contains a bool for each optional feature).
  - The default pixelformat for render target images and pipeline objects now depends on the backend:
    - for GL backends, the default pixelformat stays the same: RGBA8
    - for the Metal and D3D11 backends, the default pixelformat for render target images is now BGRA8 (the reason is because MTKView's pixelformat was always BGRA8 but this was "hidden" through an internal hack, and a BGRA swapchain is more efficient than RGBA in D3D11/DXGI)
  - Because of the above RGBA/BGRA change, you may see pixelformat validation errors in existing code if the code assumes that a render target image is always created with a default pixelformat of RGBA8.
- Changes in sokol_app.h:
  - The D3D11 backend now creates the DXGI swapchain with BGRA8 pixelformat (previously: RGBA8), this allows more efficient presentation in some situations since no format-conversion-blit needs to happen.
18-Jul-2019:
- sokol_fetch.h has been fixed and can be used again :)
11-Jul-2019:
- Don't use sokol_fetch.h for now, the current version assumes that it is possible to obtain the content size of a file from the HTTP server without downloading the entire file first. Turns out that's not possible with vanilla HTTP when the web server serves files compressed (in that case the Content-Length is the compressed size, yet JS/WASM only has access to the uncompressed data). Long story short, I need to go back to the drawing board :)
06-Jul-2019:
- new header sokol_fetch.h for asynchronously loading data.
  - make sure to carefully read the embedded documentation for making the best use of the header
  - two new samples: simple PNG file loadng with stb_image.h and MPEG1 streaming with pl_mpeg.h
- sokol_gfx.h: increased SG_MAX_SHADERSTAGE_BUFFERS configuration constant from 4 to 8.
10-Jun-2019: sokol_app.h now has proper "application quit handling":
- a pending quit can be intercepted, for instance to show a "Really Quit?" dialog box
- application code can now initiate a "soft quit" (interceptable) or "hard quit" (not interceptable)
- on the web platform, the standard "Leave Site?" dialog box implemented by browsers can be shown when the user leaves the site
- Android and iOS currently don't have any of those features (since the operating system may decide to terminate mobile applications at any time anyway, if similar features are added they will most likely have similar limitations as the web platform) For details, search for 'APPLICATION QUIT' in the sokol_app.h documentation header: https://github.com/floooh/sokol/blob/master/sokol_app.h
The imgui-highdpi-sapp contains sample code for all new quit-related features.
08-Jun-2019: some new stuff in sokol_app.h:
- the sapp_event struct has a new field bool key_repeat which is true when a keyboard event is a key-repeat (for the event types SAPP_EVENTTYPE_KEY_DOWN and SAPP_EVENTTYPE_CHAR). Many thanks to Scott Lembcke for the pull request!
- a new function to poll the internal frame counter: uint64_t sapp_frame_count(void), previously the frame counter was only available via sapp_event.
- also check out the new event-inspector sample
04-Jun-2019: All sokol headers now recognize a config-define SOKOL_DLL if sokol should be compiled into a DLL (when used with SOKOL_IMPL) or used as a DLL. On Windows, this will prepend the public function declarations with __declspec(dllexport) or __declspec(dllimport).
31-May-2019: if you're working with emscripten and fips, please note the following changes:

https://github.com/floooh/fips#public-service-announcements
27-May-2019: some D3D11 updates:
- The shader-cross-compiler can now generate D3D bytecode when running on Windows, see the sokol-shdc docs for more details.
- sokol_gfx.h no longer needs to be compiled with a SOKOL_D3D11_SHADER_COMPILER define to enable shader compilation in the D3D11 backend. Instead, the D3D shader compiler DLL (d3dcompiler_47.dll) will be loaded on-demand when the first HLSL shader needs to be compiled. If an application only uses D3D shader byte code, the compiler DLL won't be loaded into the process.
24-May-2019 The shader-cross-compiler can now generate Metal byte code for macOS or iOS when the build is running on macOS. This is enabled automatically with the fips-integration files in sokol-tools-bin, see the sokol-shdc docs for more details.
16-May-2019 two new utility headers: sokol_cimgui.h and sokol_gfx_cimgui.h, those are the same as their counterparts sokol_imgui.h and sokol_gfx_imgui.h, but use the cimgui C-API for Dear ImGui. This is useful if you don't want to - or cannot - use C++ for creating Dear ImGui UIs.

Many thanks to @prime31 for contributing those!

sokol_cimgui.h is used here, and sokol_gfx_cimgui.h is used for the debugging UI here
15-May-2019 there's now an optional shader-cross-compiler solution for sokol_gfx.h: see here for details. This is "V1.0" with two notable features missing:
- an include-file feature for GLSL shaders
- compilation to Metal- and D3D-bytecode (currently only source-code generation is supported)
The sokol-app samples have been ported to the new shader-cross-compilation, follow the src and glsl links on the specific sample webpages to see the C- and GLSL- source-code.
02-May-2019 sokol_gfx.h has a new function sg_query_backend(), this will return an enum sg_backend identifying the backend sokol-gfx is currently running on, which is one of the following values:
- SG_BACKEND_GLCORE33
- SG_BACKEND_GLES2
- SG_BACKEND_GLES3
- SG_BACKEND_D3D11
- SG_BACKEND_METAL_MACOS
- SG_BACKEND_METAL_IOS
When compiled with SOKOL_GLES3, sg_query_backend() may return SG_BACKEND_GLES2 when the runtime platform doesn't support GLES3/WebGL2 and had to fallback to GLES2/WebGL2.

When compiled with SOKOL_METAL, sg_query_backend() will return SG_BACKEND_METAL_MACOS when the compile target is macOS, and SG_BACKEND_METAL_IOS when the target is iOS.
26-Apr-2019 Small but breaking change in sokol_gfx.h how the vertex layout definition in sg_pipeline_desc works:

Vertex component names and semantics (needed by the GLES2 and D3D11 backends) have moved from sg_pipeline_desc into sg_shader_desc.

This may seem like a rather pointless small detail to change, especially for breaking existing code, but the whole thing will make a bit more sense when the new shader-cross-compiler will be integrated which I'm currently working on (here: https://github.com/floooh/sokol-tools).

While working on getting reflection data out of the shaders (e.g. what uniform blocks and textures the shader uses), it occurred to me that vertex-attribute-names and -semantics are actually part of the reflection info and belong to the shader, not to the vertex layout in the pipeline object (which only describes how the incoming vertex data maps to vertex-component slots. Instead of (optionally) mapping this association through a name, the pipeline's vertex layout is now always strictly defined in terms of numeric 'bind slots' for all sokol_gfx.h backends. For 3D APIs where the vertex component slot isn't explicitly defined in the shader language (GLES2/WebGL, D3D11, and optionally GLES3/GL), the shader merely offers a lookup table how vertex-layout slot-indices map to names/semantics (and the underlying 3D API than maps those names back to slot indices, which shows that Metal and GL made the right choice defining the slots right in the shader).

Here's how the code changes (taken from the triangle-sapp.c sample):

OLD:
```
/* create a shader */
sg_shader shd = sg_make_shader(&(sg_shader_desc){
    .vs.source = vs_src,
    .fs.source = fs_src,
});

/* create a pipeline object (default render states are fine for triangle) */
pip = sg_make_pipeline(&(sg_pipeline_desc){
    /* if the vertex layout doesn't have gaps, don't need to provide strides and offsets */
    .shader = shd,
    .layout = {
        .attrs = {
            [0] = { .name="position", .sem_name="POS", .format=SG_VERTEXFORMAT_FLOAT3 },
            [1] = { .name="color0", .sem_name="COLOR", .format=SG_VERTEXFORMAT_FLOAT4 }
        }
    },
});
```
NEW:
```
    /* create a shader */
    sg_shader shd = sg_make_shader(&(sg_shader_desc){
        .attrs = {
            [0] = { .name="position", .sem_name="POS" },
            [1] = { .name="color0", .sem_name="COLOR" }
        },
        .vs.source = vs_src,
        .fs.source = fs_src,
    });

    /* create a pipeline object (default render states are fine for triangle) */
    pip = sg_make_pipeline(&(sg_pipeline_desc){
        /* if the vertex layout doesn't have gaps, don't need to provide strides and offsets */
        .shader = shd,
        .layout = {
            .attrs = {
                [0].format=SG_VERTEXFORMAT_FLOAT3,
                [1].format=SG_VERTEXFORMAT_FLOAT4
            }
        },
    });
```
sg_shader_desc has a new embedded struct attrs which contains a vertex attribute name (for GLES2/WebGL) and sem_name/sem_index (for D3D11). For the Metal backend this struct is ignored completely, and for GLES3/GL it is optional, and not required when the vertex shader inputs are annotated with layout(location=N).

The remaining attribute description members in sg_pipeline_desc are:
- .format: the format of input vertex data (this can be different from the vertex shader's inputs when data is extended during vertex fetch (e.g. input can be vec3 while the vertex shader expects vec4)
- .offset: optional offset of the vertex component data (not needed when the input vertex has no gaps between the components)
- .buffer: the vertex buffer bind slot if the vertex data is coming from different buffers
Also check out the various samples:
- for GLSL (explicit slots via layout(location=N)): https://github.com/floooh/sokol-samples/tree/master/glfw
- for D3D11 (semantic names/indices): https://github.com/floooh/sokol-samples/tree/master/d3d11
- for GLES2: (vertex attribute names): https://github.com/floooh/sokol-samples/tree/master/html5
- for Metal: (explicit slots): https://github.com/floooh/sokol-samples/tree/master/metal
- ...and all of the above combined: https://github.com/floooh/sokol-samples/tree/master/sapp
19-Apr-2019 I have replaced the rather inflexible render-state handling in sokol_gl.h with a pipeline stack (like the GL matrix stack, but with pipeline-state-objects), along with a couple of other minor API tweaks.

These are the new pipeline-stack functions:
```
sgl_pipeline sgl_make_pipeline(const sg_pipeline_desc* desc);
void sgl_destroy_pipeline(sgl_pipeline pip);
void sgl_default_pipeline(void);
void sgl_load_pipeline(sgl_pipeline pip);
void sgl_push_pipeline(void);
void sgl_pop_pipeline(void);
```
A pipeline object is created just like in sokol_gfx.h, but without shaders, vertex layout, pixel formats, primitive-type and sample count (these details are filled in by the sgl_make_pipeline() wrapper function. For instance to create a pipeline object for additive transparency:
```
sgl_pipeline additive_pip = sgl_make_pipeline(&(sg_pipeline_desc){
    .blend = {
        .enabled = true,
        .src_factor_rgb = SG_BLENDFACTOR_ONE,
        .dst_factor_rgb = SG_BLENDFACTOR_ONE
    }
});
```
And to render with this, simply call sgl_load_pipeline():
```
sgl_load_pipeline(additive_pip);
sgl_begin_triangles();
...
sgl_end();
```
Or to preserve and restore the previously active pipeline state:
```
sgl_push_pipeline();
sgl_load_pipeline(additive_pip);
sgl_begin_quads();
...
sgl_end();
sgl_pop_pipeline();
```
You can also load the 'default pipeline' explicitly on the top of the pipeline stack with sgl_default_pipeline().

The other API change is:
- sgl_state_texture(bool b) has been replaced with sgl_enable_texture() and sgl_disable_texture()
The code samples have been updated accordingly:
- sgl-sapp.c
- sgl-lines-sapp.c
- sgl-microui-sapp.c
01-Apr-2019 (not an April Fool's joke): There's a new sokol_gl.h util header which implements an 'OpenGL-1.x-in-spirit' rendering API on top of sokol_gfx.h (vertex specification via begin/end, and a matrix stack). This is only a small subset of OpenGL 1.x, mainly intended for debug-visualization or simple tasks like 2D UI rendering. As always, sample code is in the sokol-samples project.
15-Mar-2019: various Dear ImGui related changes:
- there's a new utility header sokol_imgui.h with a simple drop-in renderer for Dear ImGui on top of sokol_gfx.h and sokol_app.h (sokol_app.h is optional, and only used for input handling)
- the sokol_gfx_imgui.h debug inspection header no longer depends on internal data structures and functions of sokol_gfx.h, as such it is now a normal utility header and has been moved to the utils directory
- the implementation macro for sokol_gfx_imgui.h has been changed from SOKOL_IMPL to SOKOL_GFX_IMGUI_IMPL (so when you suddenly get unresolved linker errors, that's the reason)
- all headers now have two preprocessor defines for the declaration and implementation (for instance in sokol_gfx.h: SOKOL_GFX_INCLUDED and SOKOL_GFX_IMPL_INCLUDED) these are checked in the utility-headers to provide useful error message when dependent headers are missing
05-Mar-2019: sokol_gfx.h now has a 'trace hook' API, and I have started implementing optional debug-inspection-UI headers on top of Dear ImGui:
- sokol_gfx.h has a new function sg_install_trace_hooks(), this allows you to install a callback function for each public sokol_gfx.h function (and a couple of error callbacks). For more details, search for "TRACE HOOKS" in sokol_gfx.h
- when creating sokol_gfx.h resources, you can now set a 'debug label' in the desc structure, this is ignored by sokol_gfx.h itself, but is useful for debuggers or profilers hooking in via the new trace hooks
- likewise, two new functions sg_push_debug_group() and sg_pop_debug_group() can be used to group related drawing functions under a name, this is also ignored by sokol_gfx.h itself and only useful when hooking into the API calls
- I have started a new 'subproject' in the 'imgui' directory, this will contain a slowly growing set of optional debug-inspection-UI headers which allow to peek under the hood of the Sokol headers. The UIs are implemented with Dear ImGui. Again, see the README in the 'imgui' directory and the headers in there for details, and check out the live demos on the Sokol Sample Webpage (click on the little UI buttons in the top right corner of each thumbnail)
21-Feb-2019: sokol_app.h and sokol_audio.h now have an alternative set of callbacks with user_data arguments. This is useful if you don't want or cannot store your own application state in global variables. See the header documentation in sokol_app.h and sokol_audio.h for details, and check out the samples sapp/noentry-sapp.c and sapp/modplay-sapp.c in https://github.com/floooh/sokol-samples
19-Feb-2019: sokol_app.h now has an alternative mode where it doesn't "hijack" the platform's main() function. Search for SOKOL_NO_ENTRY in sokol_app.h for details and documentation.
26-Jan-2019: sokol_app.h now has an Android backend contributed by Gustav Olsson! See the sokol-samples readme for build instructions.
21-Jan-2019: sokol_gfx.h - pool-slot-generation-counters and a dummy backend:
- Resource pool slots now have a generation-counter for the resource-id unique-tag, instead of a single counter for the whole pool. This allows to create many more unique handles.
- sokol_gfx.h now has a dummy backend, activated by defining SOKOL_DUMMY_BACKEND (instead of SOKOL_METAL, SOKOL_D3D11, ...), this allows to write 'headless' tests (and there's now a sokol-gfx-test in the sokol-samples repository which mainly tests the resource pool system)
12-Jan-2019: sokol_gfx.h - setting the pipeline state and resource bindings now happens in separate calls, specifically:
- sg_apply_draw_state() has been replaced with sg_apply_pipeline() and sg_apply_bindings()
- the sg_draw_state struct has been replaced with sg_bindings
- sg_apply_uniform_block() has been renamed to sg_apply_uniforms()

All existing code will still work. See this blog post for details.

29-Oct-2018:
- sokol_gfx.h has a new function sg_append_buffer() which allows to append new data to a buffer multiple times per frame and interleave this with draw calls. This basically implements the D3D11_MAP_WRITE_NO_OVERWRITE update strategy for buffer objects. For example usage, see the updated Dear ImGui samples in the sokol_samples repo
- the GL state cache in sokol_gfx.h handles buffers bindings in a more robust way, previously it might have happened that the buffer binding gets confused when creating buffers or updating buffer contents in the render loop
17-Oct-2018: sokol_args.h added
26-Sep-2018: sokol_audio.h ready for prime time :)
11-May-2018: sokol_gfx.h now autodetects iOS vs MacOS in the Metal backend during compilation using the standard define TARGET_OS_IPHONE defined in the TargetConditionals.h system header, please replace the old backend-selection defines SOKOL_METAL_MACOS and SOKOL_METAL_IOS with SOKOL_METAL
20-Apr-2018: 3 new context-switching functions have been added to make it possible to use sokol together with applications that use multiple GL contexts. On D3D11 and Metal, the functions are currently empty. See the new section WORKING WITH CONTEXTS in the sokol_gfx.h header documentation, and the new sample multiwindow-glfw
31-Jan-2018: The vertex layout declaration in sg_pipeline_desc had some fairly subtle flaws and has been changed to work like Metal or Vulkan. The gist is that the vertex-buffer-layout properties (vertex stride, vertex-step-rate and -step-function for instancing) is now defined in a separate array from the vertex attributes. This removes some brittle backend code which tries to guess the right vertex attribute slot if no attribute names are given, and which was wrong for shader-code-generation pipelines which reorder the vertex attributes (I stumbled over this when porting the Oryol Gfx module over to sokol-gfx). Some code samples:

// a complete vertex layout declaration with a single input buffer
// with two vertex attributes
sg_pipeline pip = sg_make_pipeline(&(sg_pipeline_desc){
    .layout = {
        .buffers = {
            [0] = {
                .stride = 20,
                .step_func = SG_VERTEXSTEP_PER_VERTEX,
                .step_rate = 1
            }
        },
        .attrs = {
            [0] = {
                .name = "pos",
                .offset = 0,
                .format = SG_VERTEXFORMAT_FLOAT3,
                .buffer_index = 0
            },
            [1] = {
                .name = "uv",
                .offset = 12,
                .format = SG_VERTEXFORMAT_FLOAT2,
                .buffer_index = 0
            }
        }
    },
    ...
});

// if the vertex layout has no gaps, we can get rid of the strides and offsets:
sg_pipeline pip = sg_make_pipeline(&(sg_pipeline_desc){
    .layout = {
        .buffers = {
            [0] = {
                .step_func = SG_VERTEXSTEP_PER_VERTEX,
                .step_rate=1
            }
        },
        .attrs = {
            [0] = {
                .name = "pos",
                .format = SG_VERTEXFORMAT_FLOAT3,
                .buffer_index = 0
            },
            [1] = {
                .name = "uv",
                .format = SG_VERTEXFORMAT_FLOAT2,
                .buffer_index = 0
            }
        }
    },
    ...
});

// we can also get rid of the other default-values, which leaves buffers[0]
// as all-defaults, so it can disappear completely:
sg_pipeline pip = sg_make_pipeline(&(sg_pipeline_desc){
    .layout = {
        .attrs = {
            [0] = { .name = "pos", .format = SG_VERTEXFORMAT_FLOAT3 },
            [1] = { .name = "uv", .format = SG_VERTEXFORMAT_FLOAT2 }
        }
    },
    ...
});

// and finally on GL3.3 and Metal and we don't need the attribute names
// (on D3D11, a semantic name and index must be provided though)
sg_pipeline pip = sg_make_pipeline(&(sg_pipeline_desc){
    .layout = {
        .attrs = {
            [0] = { .format = SG_VERTEXFORMAT_FLOAT3 },
            [1] = { .format = SG_VERTEXFORMAT_FLOAT2 }
        }
    },
    ...
});

Please check the sample code in https://github.com/floooh/sokol-samples for more examples!

Enjoy!

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