MANUAL.md

Nuance shaders

Shaders are preferably written with the Vulkan flavor of GLSL (#version 460). The GL_KHR_vulkan_glsl extension is implicitly enabled.

Great resources to learn about shaders :

• thebookofshaders.com

Supported languages

Support	GLSL	WGSL	Rust	SpirV
Tier 0 / Import	✔️	✔️		✔️*
Tier 1 / Std	✔️
Tier 2 / Params	✔️

* The compiled shader need to comply with the expected interface.

Shader inputs

Access the current sample coordinates with fragCoord. The origin is the upper left. For normalized 0-1 coordinates, use fragCoordNorm.

You can also use a bunch of globals passed to your shader at each invocation to handle user input, get canvas dimension and access time.

layout(push_constant) uniform Globals {
// Window resolution
    uvec2 uResolution;
// Mouse position
    uvec2 uMouse;
// Mouse wheel
    float fMouseWheel;
// Aspect ratio
    float fRatio;
// Time in sec
    float fTime;
// The number of frame we're at
    uint uFrame;
};

For used defined parameters, see Parameters.

Shader output

layout(location = 0) out vec4 fragColor;

Use fragColor to define the fragment color. Example :

void main() {
    fragColor = vec4(1.0, 0.0, 0.0, 1.0);
}

Conditional compilation

Compiling your shader with Nuance guarantees NUANCE is defined.

#define NUANCE

You can use it for conditional compilation.

#ifdef NUANCE
...
#else
...
#endif

Special settings

You can set some settings in your shader with defines.

Reactive or continuous rendering

Use #define NUANCE_STILL_IMAGE when your shader doesn't need continuous rendering because of an animation. This prevents running it at a given framerate. This has no effect right now !

Parameters

Nuance allows you to define parameters for your shader. Before compiling your shader, parameters will be parsed from the source code to generate sliders and other appropriate UI elements. Example :

layout(params) uniform Params {
    layout(min = 0, max = 100, init = 1) float myValue;
    layout(min = 0, max = 20) float otherValue;
};

Each parameter UI appearance is derived from its type and qualifiers.

Parameters types

type	qualifiers	ui
float	min = ?, max = ?, init = ?	drag control
vec2	init = ?	double drag control
vec3	color, init = ?	color picker
vec3	init = ?	triple drag control
bool	init = ?	checkbox

Special values

You can use the values you defined in the qualifiers using the dot notation. Those expressions will be replaced at compile time. Example :

void main() {
    fragColor = vec4(myValue / myValue.max, 0.0, 0.0, 1.0);
}

Special values

FIRST_RUN

#define FIRST_RUN uFrame == 0

Has the value true if this shader invocation the first one since the last reset. Useful to set up an initial state. This define should not be used for conditional compilation !

Standard functions

By including the standard header #include <Nuance>, you also get access to some useful functions

Noise

Utility functions around noise and randomness.

float noise(vec2)

Generates a pseudo random value from a vec2. The returned value only depends on the vec2 parameter. Source : https://thebookofshaders.com/10/

Previous render

Utility functions to sample the previous texture.

vec4 samplePrevious()

Sample the previously rendered texture at the current fragment coordinates.

vec4 samplePrevious(vec2)

Sample the previously rendered texture at the given coordinates.

vec4 samplePreviousN(vec2)

Sample the previously rendered texture at the given normalized coordinates.