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fixes #487
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Support image as_is flag in loading and saving
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@ptc-tgamper
ptc-tgamper committed Jun 28, 2024
1 parent 3245906 commit d522c9e
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Showing 2 changed files with 197 additions and 53 deletions.
108 changes: 102 additions & 6 deletions tests/tester.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1060,11 +1060,10 @@ TEST_CASE("serialize-lods", "[lods]") {
}

TEST_CASE("write-image-issue", "[issue-473]") {

tinygltf::Model model;
tinygltf::TinyGLTF ctx;
std::string err;
std::string warn;
tinygltf::Model model;
tinygltf::TinyGLTF ctx;
bool ok = ctx.LoadASCIIFromFile(&model, &err, &warn, "../models/Cube/Cube.gltf");
REQUIRE(ok);
REQUIRE(err.empty());
Expand All @@ -1077,12 +1076,109 @@ TEST_CASE("write-image-issue", "[issue-473]") {
REQUIRE_FALSE(model.images[0].image.empty());
REQUIRE_FALSE(model.images[1].image.empty());

ok = ctx.WriteGltfSceneToFile(&model, "Cube.gltf", false, true);
ok = ctx.WriteGltfSceneToFile(&model, "Cube.gltf");
REQUIRE(ok);

for (const auto& image : model.images)
{
for (const auto& image : model.images) {
std::fstream file(image.uri);
CHECK(file.good());
}
}

TEST_CASE("images-as-is", "[issue-487]") {
std::string err;
std::string warn;
tinygltf::Model model;
tinygltf::TinyGLTF ctx;
ctx.SetImagesAsIs(true);
bool ok = ctx.LoadASCIIFromFile(&model, &err, &warn, "../models/Cube/Cube.gltf");
REQUIRE(ok);
REQUIRE(err.empty());
REQUIRE(warn.empty());

for (const auto& image : model.images) {
CHECK(image.as_is == true);
CHECK_FALSE(image.uri.empty());
CHECK_FALSE(image.image.empty());

#ifndef TINYGLTF_NO_STB_IMAGE
// Make sure we can decode the images
int w = -1, h = -1, component = -1;
unsigned char *data = stbi_load_from_memory(image.image.data(), static_cast<int>(image.image.size()), &w, &h, &component, 0);
CHECK(data != nullptr);
CHECK(w == 512);
CHECK(h == 512);
CHECK(component >= 3);
stbi_image_free(data);
#endif
}

// Write glTF model to disk, and images as separate files
{
ok = ctx.WriteGltfSceneToFile(&model, "Cube_with_image_files.gltf");
REQUIRE(ok);

// All the images should have been written to disk with their original data
for (const auto& image : model.images) {
// Make sure the image files exist
std::fstream file(image.uri);
CHECK(file.good());
#ifndef TINYGLTF_NO_STB_IMAGE
// Make sure we can load the images
int w = -1, h = -1, component = -1;
unsigned char *data = stbi_load(image.uri.c_str(), &w, &h, &component, 0);
CHECK(data != nullptr);
CHECK(w == 512);
CHECK(h == 512);
CHECK(component >= 3);
stbi_image_free(data);
#endif
}
}

// Write glTF model to disk, and embed images as data URIs
{
ok = ctx.WriteGltfSceneToFile(&model, "Cube_with_embedded_images.gltf", true, false);
REQUIRE(ok);

// Load above model again, and check if the images are loaded properly
tinygltf::Model embeddedImages;
ctx.SetImagesAsIs(false);
bool ok = ctx.LoadASCIIFromFile(&embeddedImages, &err, &warn, "Cube_with_embedded_images.gltf");
REQUIRE(ok);
REQUIRE(err.empty());
REQUIRE(warn.empty());

for (const auto& image : embeddedImages.images) {
CHECK(image.as_is == false);
CHECK_FALSE(image.mimeType.empty());
CHECK_FALSE(image.image.empty());
CHECK(image.width == 512);
CHECK(image.height == 512);
CHECK(image.component >= 3);
}
}

// Write glTF model to disk, as GLB
{
ok = ctx.WriteGltfSceneToFile(&model, "Cube.glb", true, true, true, true);
REQUIRE(ok);

// Load above model again, and check if the images are loaded properly
tinygltf::Model glbModel;
ctx.SetImagesAsIs(false);
bool ok = ctx.LoadBinaryFromFile(&glbModel, &err, &warn, "Cube.glb");
REQUIRE(ok);
REQUIRE(err.empty());
REQUIRE(warn.empty());

for (const auto& image : glbModel.images) {
CHECK(image.as_is == false);
CHECK_FALSE(image.mimeType.empty());
CHECK_FALSE(image.image.empty());
CHECK(image.width == 512);
CHECK(image.height == 512);
CHECK(image.component >= 3);
}
}
}
142 changes: 95 additions & 47 deletions tiny_gltf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -649,9 +649,7 @@ struct Image {
// When this flag is true, data is stored to `image` in as-is format(e.g. jpeg
// compressed for "image/jpeg" mime) This feature is good if you use custom
// image loader function. (e.g. delayed decoding of images for faster glTF
// parsing) Default parser for Image does not provide as-is loading feature at
// the moment. (You can manipulate this by providing your own LoadImageData
// function)
// parsing).
bool as_is{false};

Image() = default;
Expand Down Expand Up @@ -1544,6 +1542,17 @@ class TinyGLTF {
preserve_image_channels_ = onoff;
}

bool GetPreserveImageChannels() const { return preserve_image_channels_; }

///
/// Specifiy whether image data is decoded/decompressed during load, or left as is
///
void SetImagesAsIs(bool onoff) {
images_as_is_ = onoff;
}

bool GetImagesAsIs() const { return images_as_is_; }

///
/// Set maximum allowed external file size in bytes.
/// Default: 2GB
Expand All @@ -1555,8 +1564,6 @@ class TinyGLTF {

size_t GetMaxExternalFileSize() const { return max_external_file_size_; }

bool GetPreserveImageChannels() const { return preserve_image_channels_; }

private:
///
/// Loads glTF asset from string(memory).
Expand All @@ -1581,6 +1588,8 @@ class TinyGLTF {
bool preserve_image_channels_ = false; /// Default false(expand channels to
/// RGBA) for backward compatibility.

bool images_as_is_ = false; /// Default false (decode/decompress images)

size_t max_external_file_size_{
size_t((std::numeric_limits<int32_t>::max)())}; // Default 2GB

Expand Down Expand Up @@ -1906,6 +1915,9 @@ struct LoadImageDataOption {
// channels) default `false`(channels are expanded to RGBA for backward
// compatibility).
bool preserve_channels{false};
// true: do not decode/decompress image data.
// default `false`: decode/decompress image data.
bool as_is{false};
};

// Equals function for Value, for recursivity
Expand Down Expand Up @@ -2614,48 +2626,65 @@ bool LoadImageData(Image *image, const int image_idx, std::string *err,

int w = 0, h = 0, comp = 0, req_comp = 0;

unsigned char *data = nullptr;
// Try to decode image header
if (!stbi_info_from_memory(bytes, size, &w, &h, &comp)) {
// On failure, if we load images as is, we just warn.
std::string* msgOut = option.as_is ? warn : err;
if (msgOut) {
(*msgOut) +=
"Unknown image format. STB cannot decode image header for image[" +
std::to_string(image_idx) + "] name = \"" + image->name + "\".\n";
}
if (!option.as_is) {
// If we decode images, error out.
return false;
} else {
// If we load images as is, we copy the image data,
// set all image properties to invalid, and report success.
image->width = image->height = image->component = -1;
image->bits = image->pixel_type = -1;
image->image.resize(static_cast<size_t>(size));
std::copy(bytes, bytes + size, image->image.begin());
return true;
}
}

// preserve_channels true: Use channels stored in the image file.
// false: force 32-bit textures for common Vulkan compatibility. It appears
// that some GPU drivers do not support 24-bit images for Vulkan
req_comp = option.preserve_channels ? 0 : 4;
int bits = 8;
int pixel_type = TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE;

// It is possible that the image we want to load is a 16bit per channel image
// We are going to attempt to load it as 16bit per channel, and if it worked,
// set the image data accordingly. We are casting the returned pointer into
// unsigned char, because we are representing "bytes". But we are updating
// the Image metadata to signal that this image uses 2 bytes (16bits) per
// channel:
if (stbi_is_16_bit_from_memory(bytes, size)) {
data = reinterpret_cast<unsigned char *>(
stbi_load_16_from_memory(bytes, size, &w, &h, &comp, req_comp));
if (data) {
bits = 16;
pixel_type = TINYGLTF_COMPONENT_TYPE_UNSIGNED_SHORT;
}
}

// at this point, if data is still NULL, it means that the image wasn't
// 16bit per channel, we are going to load it as a normal 8bit per channel
// image as we used to do:
// if image cannot be decoded, ignore parsing and keep it by its path
// don't break in this case
// FIXME we should only enter this function if the image is embedded. If
// image->uri references
// an image file, it should be left as it is. Image loading should not be
// mandatory (to support other formats)
if (!data) data = stbi_load_from_memory(bytes, size, &w, &h, &comp, req_comp);
if (!data) {
// NOTE: you can use `warn` instead of `err`
if (err) {
(*err) +=
"Unknown image format. STB cannot decode image data for image[" +
std::to_string(image_idx) + "] name = \"" + image->name + "\".\n";
bits = 16;
pixel_type = TINYGLTF_COMPONENT_TYPE_UNSIGNED_SHORT;
}

// preserve_channels true: Use channels stored in the image file.
// false: force 32-bit textures for common Vulkan compatibility. It appears
// that some GPU drivers do not support 24-bit images for Vulkan
req_comp = (option.preserve_channels || option.as_is) ? 0 : 4;

unsigned char* data = nullptr;
// Perform image decoding if requested
if (!option.as_is) {
// If the image is marked as 16 bit per channel, attempt to decode it as such first.
// If that fails, we are going to attempt to load it as 8 bit per channel image.
if (bits == 16) {
data = reinterpret_cast<unsigned char *>(stbi_load_16_from_memory(bytes, size, &w, &h, &comp, req_comp));
}
// Load as 8 bit per channel data
if (!data) {
data = stbi_load_from_memory(bytes, size, &w, &h, &comp, req_comp);
if (!data) {
if (err) {
(*err) +=
"Unknown image format. STB cannot decode image data for image[" +
std::to_string(image_idx) + "] name = \"" + image->name + "\".\n";
}
return false;
}
// If we were succesful, mark as 8 bit
bits = 8;
pixel_type = TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE;
}
return false;
}

if ((w < 1) || (h < 1)) {
Expand Down Expand Up @@ -2701,10 +2730,20 @@ bool LoadImageData(Image *image, const int image_idx, std::string *err,
image->component = comp;
image->bits = bits;
image->pixel_type = pixel_type;
image->image.resize(static_cast<size_t>(w * h * comp) * size_t(bits / 8));
std::copy(data, data + w * h * comp * (bits / 8), image->image.begin());
stbi_image_free(data);
image->as_is = option.as_is;

if (option.as_is) {
// Store the original image data
image->image.resize(static_cast<size_t>(size));
std::copy(bytes, bytes + size, image->image.begin());
}
else {
// Store the decoded image data
image->image.resize(static_cast<size_t>(w * h * comp) * size_t(bits / 8));
std::copy(data, data + w * h * comp * (bits / 8), image->image.begin());
}

stbi_image_free(data);
return true;
}
#endif
Expand Down Expand Up @@ -2734,28 +2773,36 @@ bool WriteImageData(const std::string *basepath, const std::string *filename,
std::string header;
std::vector<unsigned char> data;

// If the image data is already encoded, take it as is
if (image->as_is) {
data = image->image;
}

if (ext == "png") {
if ((image->bits != 8) ||
(image->pixel_type != TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE)) {
// Unsupported pixel format
return false;
}

if (!stbi_write_png_to_func(WriteToMemory_stbi, &data, image->width,
if (!image->as_is &&
!stbi_write_png_to_func(WriteToMemory_stbi, &data, image->width,
image->height, image->component,
&image->image[0], 0)) {
return false;
}
header = "data:image/png;base64,";
} else if (ext == "jpg") {
if (!stbi_write_jpg_to_func(WriteToMemory_stbi, &data, image->width,
if (!image->as_is &&
!stbi_write_jpg_to_func(WriteToMemory_stbi, &data, image->width,
image->height, image->component,
&image->image[0], 100)) {
return false;
}
header = "data:image/jpeg;base64,";
} else if (ext == "bmp") {
if (!stbi_write_bmp_to_func(WriteToMemory_stbi, &data, image->width,
if (!image->as_is &&
!stbi_write_bmp_to_func(WriteToMemory_stbi, &data, image->width,
image->height, image->component,
&image->image[0])) {
return false;
Expand Down Expand Up @@ -6360,6 +6407,7 @@ bool TinyGLTF::LoadFromString(Model *model, std::string *err, std::string *warn,
load_image_user_data = load_image_user_data_;
} else {
load_image_option.preserve_channels = preserve_image_channels_;
load_image_option.as_is = images_as_is_;
load_image_user_data = reinterpret_cast<void *>(&load_image_option);
}

Expand Down

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