gltfpack: Add basic support for EXT_texture_webp

Similarly to KHR_texture_basisu appearing in the input, we now preserve
webp images along with the extension if they are present in the input
file.

gltf/gltfpack.cpp

@@ -454,6 +454,7 @@ static void process(cgltf_data* data, const char* input_path, const char* output
 	bool ext_instancing = false;
 	bool ext_texture_transform = false;
 	bool ext_texture_basisu = false;
+	bool ext_texture_webp = false;
 
 	size_t accr_offset = 0;
 	size_t node_offset = 0;
@@ -512,6 +513,7 @@ static void process(cgltf_data* data, const char* input_path, const char* output
 		assert(textures[i].remap == int(texture_offset));
 		texture_offset++;
 		ext_texture_basisu = ext_texture_basisu || texture.has_basisu;
+		ext_texture_webp = ext_texture_webp || texture.has_webp;
 	}
 
 	for (size_t i = 0; i < data->materials_count; ++i)
@@ -838,6 +840,7 @@ static void process(cgltf_data* data, const char* input_path, const char* output
 	    {"KHR_materials_variants", data->variants_count > 0, false},
 	    {"KHR_lights_punctual", data->lights_count > 0, false},
 	    {"KHR_texture_basisu", (!json_textures.empty() && settings.texture_ktx2) || ext_texture_basisu, true},
+	    {"EXT_texture_webp", ext_texture_webp, true},
 	    {"EXT_mesh_gpu_instancing", ext_instancing, true},
 	};
 

gltf/image.cpp

@@ -8,6 +8,7 @@ static const char* kMimeTypes[][2] = {
     {"image/jpeg", ".jpeg"},
     {"image/png", ".png"},
     {"image/ktx2", ".ktx2"},
+    {"image/webp", ".webp"},
 };
 
 static const char* inferMimeType(const char* path)

gltf/material.cpp

@@ -11,10 +11,10 @@ static bool areTexturesEqual(const cgltf_texture& lhs, const cgltf_texture& rhs)
 	if (lhs.sampler != rhs.sampler)
 		return false;
 
-	if (lhs.has_basisu != rhs.has_basisu)
+	if (lhs.basisu_image != rhs.basisu_image)
 		return false;
 
-	if (lhs.basisu_image != rhs.basisu_image)
+	if (lhs.webp_image != rhs.webp_image)
 		return false;
 
 	return true;
@@ -446,9 +446,12 @@ static const cgltf_image* getTextureImage(const cgltf_texture* texture)
 	if (texture && texture->image)
 		return texture->image;
 
-	if (texture && texture->has_basisu && texture->basisu_image)
+	if (texture && texture->basisu_image)
 		return texture->basisu_image;
 
+	if (texture && texture->webp_image)
+		return texture->webp_image;
+
 	return NULL;
 }
 

gltf/write.cpp

@@ -975,13 +975,20 @@ void writeTexture(std::string& json, const cgltf_texture& texture, const ImageIn
 		}
 	}
 
-	if (texture.has_basisu && texture.basisu_image)
+	if (texture.basisu_image)
 	{
 		comma(json);
 		append(json, "\"extensions\":{\"KHR_texture_basisu\":{\"source\":");
 		append(json, size_t(texture.basisu_image - data->images));
 		append(json, "}}");
 	}
+	else if (texture.webp_image)
+	{
+		comma(json);
+		append(json, "\"extensions\":{\"EXT_texture_webp\":{\"source\":");
+		append(json, size_t(texture.webp_image - data->images));
+		append(json, "}}");
+	}
 }
 
 void writeMeshAttributes(std::string& json, std::vector<BufferView>& views, std::string& json_accessors, size_t& accr_offset, const Mesh& mesh, int target, const QuantizationPosition& qp, const QuantizationTexture& qt, const Settings& settings)