gltfpack: Implement support for KHR_materials_diffuse_transmission

extern/cgltf.h

@@ -500,6 +500,14 @@ typedef struct cgltf_iridescence
 	cgltf_texture_view iridescence_thickness_texture;
 } cgltf_iridescence;
 
+typedef struct cgltf_diffuse_transmission
+{
+	cgltf_texture_view diffuse_transmission_texture;
+	cgltf_float diffuse_transmission_factor;
+	cgltf_float diffuse_transmission_color_factor[3];
+	cgltf_texture_view diffuse_transmission_color_texture;
+} cgltf_diffuse_transmission;
+
 typedef struct cgltf_anisotropy
 {
 	cgltf_float anisotropy_strength;
@@ -525,6 +533,7 @@ typedef struct cgltf_material
 	cgltf_bool has_sheen;
 	cgltf_bool has_emissive_strength;
 	cgltf_bool has_iridescence;
+	cgltf_bool has_diffuse_transmission;
 	cgltf_bool has_anisotropy;
 	cgltf_bool has_dispersion;
 	cgltf_pbr_metallic_roughness pbr_metallic_roughness;
@@ -537,6 +546,7 @@ typedef struct cgltf_material
 	cgltf_volume volume;
 	cgltf_emissive_strength emissive_strength;
 	cgltf_iridescence iridescence;
+	cgltf_diffuse_transmission diffuse_transmission;
 	cgltf_anisotropy anisotropy;
 	cgltf_dispersion dispersion;
 	cgltf_texture_view normal_texture;
@@ -4278,6 +4288,51 @@ static int cgltf_parse_json_iridescence(cgltf_options* options, jsmntok_t const*
 	return i;
 }
 
+static int cgltf_parse_json_diffuse_transmission(cgltf_options* options, jsmntok_t const* tokens, int i, const uint8_t* json_chunk, cgltf_diffuse_transmission* out_diff_transmission)
+{
+	CGLTF_CHECK_TOKTYPE(tokens[i], JSMN_OBJECT);
+	int size = tokens[i].size;
+	++i;
+
+	// Defaults
+	cgltf_fill_float_array(out_diff_transmission->diffuse_transmission_color_factor, 3, 1.0f);
+
+	for (int j = 0; j < size; ++j)
+	{
+		CGLTF_CHECK_KEY(tokens[i]);
+
+		if (cgltf_json_strcmp(tokens + i, json_chunk, "diffuseTransmissionFactor") == 0)
+		{
+			++i;
+			out_diff_transmission->diffuse_transmission_factor = cgltf_json_to_float(tokens + i, json_chunk);
+			++i;
+		}
+		else if (cgltf_json_strcmp(tokens + i, json_chunk, "diffuseTransmissionTexture") == 0)
+		{
+			i = cgltf_parse_json_texture_view(options, tokens, i + 1, json_chunk, &out_diff_transmission->diffuse_transmission_texture);
+		}
+		else if (cgltf_json_strcmp(tokens + i, json_chunk, "diffuseTransmissionColorFactor") == 0)
+		{
+			i = cgltf_parse_json_float_array(tokens, i + 1, json_chunk, out_diff_transmission->diffuse_transmission_color_factor, 3);
+		}
+		else if (cgltf_json_strcmp(tokens + i, json_chunk, "diffuseTransmissionColorTexture") == 0)
+		{
+			i = cgltf_parse_json_texture_view(options, tokens, i + 1, json_chunk, &out_diff_transmission->diffuse_transmission_color_texture);
+		}
+		else
+		{
+			i = cgltf_skip_json(tokens, i + 1);
+		}
+
+		if (i < 0)
+		{
+			return i;
+		}
+	}
+
+	return i;
+}
+
 static int cgltf_parse_json_anisotropy(cgltf_options* options, jsmntok_t const* tokens, int i, const uint8_t* json_chunk, cgltf_anisotropy* out_anisotropy)
 {
 	CGLTF_CHECK_TOKTYPE(tokens[i], JSMN_OBJECT);
@@ -4766,6 +4821,11 @@ static int cgltf_parse_json_material(cgltf_options* options, jsmntok_t const* to
 					out_material->has_iridescence = 1;
 					i = cgltf_parse_json_iridescence(options, tokens, i + 1, json_chunk, &out_material->iridescence);
 				}
+				else if (cgltf_json_strcmp(tokens + i, json_chunk, "KHR_materials_diffuse_transmission") == 0)
+				{
+					out_material->has_diffuse_transmission = 1;
+					i = cgltf_parse_json_diffuse_transmission(options, tokens, i + 1, json_chunk, &out_material->diffuse_transmission);
+				}
 				else if (cgltf_json_strcmp(tokens + i, json_chunk, "KHR_materials_anisotropy") == 0)
 				{
 					out_material->has_anisotropy = 1;
@@ -6629,6 +6689,9 @@ static int cgltf_fixup_pointers(cgltf_data* data)
 		CGLTF_PTRFIXUP(data->materials[i].iridescence.iridescence_texture.texture, data->textures, data->textures_count);
 		CGLTF_PTRFIXUP(data->materials[i].iridescence.iridescence_thickness_texture.texture, data->textures, data->textures_count);
 
+		CGLTF_PTRFIXUP(data->materials[i].diffuse_transmission.diffuse_transmission_texture.texture, data->textures, data->textures_count);
+		CGLTF_PTRFIXUP(data->materials[i].diffuse_transmission.diffuse_transmission_color_texture.texture, data->textures, data->textures_count);
+
 		CGLTF_PTRFIXUP(data->materials[i].anisotropy.anisotropy_texture.texture, data->textures, data->textures_count);
 	}
 

gltf/README.md

@@ -69,6 +69,7 @@ gltfpack supports most Khronos extensions and some multi-vendor extensions in th
 - KHR_lights_punctual
 - KHR_materials_anisotropy
 - KHR_materials_clearcoat
+- KHR_materials_diffuse_transmission
 - KHR_materials_dispersion
 - KHR_materials_emissive_strength
 - KHR_materials_ior

gltf/gltfpack.cpp

@@ -480,6 +480,7 @@ static void process(cgltf_data* data, const char* input_path, const char* output
 	bool ext_iridescence = false;
 	bool ext_anisotropy = false;
 	bool ext_dispersion = false;
+	bool ext_diffuse_transmission = false;
 	bool ext_unlit = false;
 	bool ext_instancing = false;
 	bool ext_texture_transform = false;
@@ -574,6 +575,7 @@ static void process(cgltf_data* data, const char* input_path, const char* output
 		ext_volume = ext_volume || material.has_volume;
 		ext_emissive_strength = ext_emissive_strength || material.has_emissive_strength;
 		ext_iridescence = ext_iridescence || material.has_iridescence;
+		ext_diffuse_transmission = ext_diffuse_transmission || material.has_diffuse_transmission;
 		ext_anisotropy = ext_anisotropy || material.has_anisotropy;
 		ext_dispersion = ext_dispersion || material.has_dispersion;
 		ext_unlit = ext_unlit || material.unlit;
@@ -856,6 +858,7 @@ static void process(cgltf_data* data, const char* input_path, const char* output
 	    {"KHR_materials_iridescence", ext_iridescence, false},
 	    {"KHR_materials_anisotropy", ext_anisotropy, false},
 	    {"KHR_materials_dispersion", ext_dispersion, false},
+	    {"KHR_materials_diffuse_transmission", ext_diffuse_transmission, false},
 	    {"KHR_materials_unlit", ext_unlit, false},
 	    {"KHR_materials_variants", data->variants_count > 0, false},
 	    {"KHR_lights_punctual", data->lights_count > 0, false},

gltf/material.cpp

@@ -246,6 +246,23 @@ static bool areMaterialComponentsEqual(const cgltf_dispersion& lhs, const cgltf_
 	return true;
 }
 
+static bool areMaterialComponentsEqual(const cgltf_diffuse_transmission& lhs, const cgltf_diffuse_transmission& rhs)
+{
+	if (lhs.diffuse_transmission_factor != rhs.diffuse_transmission_factor)
+		return false;
+
+	if (memcmp(lhs.diffuse_transmission_color_factor, rhs.diffuse_transmission_color_factor, sizeof(cgltf_float) * 3) != 0)
+		return false;
+
+	if (!areTextureViewsEqual(lhs.diffuse_transmission_texture, rhs.diffuse_transmission_texture))
+		return false;
+
+	if (!areTextureViewsEqual(lhs.diffuse_transmission_color_texture, rhs.diffuse_transmission_color_texture))
+		return false;
+
+	return true;
+}
+
 static bool areMaterialsEqual(const cgltf_material& lhs, const cgltf_material& rhs, const Settings& settings)
 {
 	if (lhs.has_pbr_metallic_roughness != rhs.has_pbr_metallic_roughness)
@@ -320,6 +337,12 @@ static bool areMaterialsEqual(const cgltf_material& lhs, const cgltf_material& r
 	if (lhs.has_dispersion && !areMaterialComponentsEqual(lhs.dispersion, rhs.dispersion))
 		return false;
 
+	if (lhs.has_diffuse_transmission != rhs.has_diffuse_transmission)
+		return false;
+
+	if (lhs.has_diffuse_transmission && !areMaterialComponentsEqual(lhs.diffuse_transmission, rhs.diffuse_transmission))
+		return false;
+
 	if (!areTextureViewsEqual(lhs.normal_texture, rhs.normal_texture))
 		return false;
 
@@ -535,6 +558,12 @@ static void analyzeMaterial(const cgltf_material& material, MaterialInfo& mi, cg
 		analyzeMaterialTexture(material.anisotropy.anisotropy_texture, TextureKind_Normal, mi, data, textures, images);
 	}
 
+	if (material.has_diffuse_transmission)
+	{
+		analyzeMaterialTexture(material.diffuse_transmission.diffuse_transmission_texture, TextureKind_Attrib, mi, data, textures, images);
+		analyzeMaterialTexture(material.diffuse_transmission.diffuse_transmission_color_texture, TextureKind_Color, mi, data, textures, images);
+	}
+
 	analyzeMaterialTexture(material.normal_texture, TextureKind_Normal, mi, data, textures, images);
 	analyzeMaterialTexture(material.occlusion_texture, TextureKind_Attrib, mi, data, textures, images);
 	analyzeMaterialTexture(material.emissive_texture, TextureKind_Color, mi, data, textures, images);

gltf/write.cpp

@@ -550,6 +550,37 @@ static void writeMaterialComponent(std::string& json, const cgltf_data* data, co
 	append(json, "}");
 }
 
+static void writeMaterialComponent(std::string& json, const cgltf_data* data, const cgltf_diffuse_transmission& tm, const QuantizationTexture* qt, std::vector<TextureInfo>& textures)
+{
+	comma(json);
+	append(json, "\"KHR_materials_diffuse_transmission\":{");
+	if (tm.diffuse_transmission_factor != 0)
+	{
+		comma(json);
+		append(json, "\"diffuseTransmissionFactor\":");
+		append(json, tm.diffuse_transmission_factor);
+	}
+	if (tm.diffuse_transmission_texture.texture)
+	{
+		comma(json);
+		append(json, "\"diffuseTransmissionTexture\":");
+		writeTextureInfo(json, data, tm.diffuse_transmission_texture, qt, textures);
+	}
+	if (memcmp(tm.diffuse_transmission_color_factor, white, sizeof(float) * 3) != 0)
+	{
+		comma(json);
+		append(json, "\"diffuseTransmissionColorFactor\":");
+		append(json, tm.diffuse_transmission_color_factor, 3);
+	}
+	if (tm.diffuse_transmission_color_texture.texture)
+	{
+		comma(json);
+		append(json, "\"diffuseTransmissionColorTexture\":");
+		writeTextureInfo(json, data, tm.diffuse_transmission_color_texture, qt, textures);
+	}
+	append(json, "}");
+}
+
 void writeMaterial(std::string& json, const cgltf_data* data, const cgltf_material& material, const QuantizationPosition* qp, const QuantizationTexture* qt, std::vector<TextureInfo>& textures)
 {
 	if (material.name && *material.name)
@@ -614,7 +645,9 @@ void writeMaterial(std::string& json, const cgltf_data* data, const cgltf_materi
 		append(json, "\"doubleSided\":true");
 	}
 
-	if (material.has_pbr_specular_glossiness || material.has_clearcoat || material.has_transmission || material.has_ior || material.has_specular || material.has_sheen || material.has_volume || material.has_emissive_strength || material.has_iridescence || material.has_anisotropy || material.has_dispersion || material.unlit)
+	if (material.has_pbr_specular_glossiness || material.has_clearcoat || material.has_transmission || material.has_ior || material.has_specular ||
+	    material.has_sheen || material.has_volume || material.has_emissive_strength || material.has_iridescence || material.has_anisotropy ||
+	    material.has_dispersion || material.has_diffuse_transmission || material.unlit)
 	{
 		comma(json);
 		append(json, "\"extensions\":{");
@@ -652,6 +685,9 @@ void writeMaterial(std::string& json, const cgltf_data* data, const cgltf_materi
 		if (material.has_dispersion)
 			writeMaterialComponent(json, data, material.dispersion);
 
+		if (material.has_diffuse_transmission)
+			writeMaterialComponent(json, data, material.diffuse_transmission, qt, textures);
+
 		if (material.unlit)
 		{
 			comma(json);