Merge pull request #170 from abwood/emissive-strength

Add support for KHR_materials_emissive_strength.

README.md

@@ -112,6 +112,8 @@ cgltf also supports some glTF extensions:
 - KHR_materials_variants
 - KHR_materials_volume
 - KHR_texture_transform
+- KHR_texture_basisu (requires a library like [Binomial Basisu](https://github.com/BinomialLLC/basis_universal) for transcoding to native compressed texture)
+- KHR_materials_emissive_strength
 
 cgltf does **not** yet support unlisted extensions. However, unlisted extensions can be accessed via "extensions" member on objects.
 

cgltf.h

@@ -474,6 +474,11 @@ typedef struct cgltf_sheen
 	cgltf_float sheen_roughness_factor;
 } cgltf_sheen;
 
+typedef struct cgltf_emissive_strength
+{
+	cgltf_float emissive_strength;
+} cgltf_emissive_strength;
+
 typedef struct cgltf_material
 {
 	char* name;
@@ -485,6 +490,7 @@ typedef struct cgltf_material
 	cgltf_bool has_ior;
 	cgltf_bool has_specular;
 	cgltf_bool has_sheen;
+	cgltf_bool has_emissive_strength;
 	cgltf_pbr_metallic_roughness pbr_metallic_roughness;
 	cgltf_pbr_specular_glossiness pbr_specular_glossiness;
 	cgltf_clearcoat clearcoat;
@@ -493,6 +499,7 @@ typedef struct cgltf_material
 	cgltf_sheen sheen;
 	cgltf_transmission transmission;
 	cgltf_volume volume;
+	cgltf_emissive_strength emissive_strength;
 	cgltf_texture_view normal_texture;
 	cgltf_texture_view occlusion_texture;
 	cgltf_texture_view emissive_texture;
@@ -3844,6 +3851,39 @@ static int cgltf_parse_json_sheen(cgltf_options* options, jsmntok_t const* token
 	return i;
 }
 
+static int cgltf_parse_json_emissive_strength(jsmntok_t const* tokens, int i, const uint8_t* json_chunk, cgltf_emissive_strength* out_emissive_strength)
+{
+	CGLTF_CHECK_TOKTYPE(tokens[i], JSMN_OBJECT);
+	int size = tokens[i].size;
+	++i;
+
+	// Default
+	out_emissive_strength->emissive_strength = 1.f;
+
+	for (int j = 0; j < size; ++j)
+	{
+		CGLTF_CHECK_KEY(tokens[i]);
+
+		if (cgltf_json_strcmp(tokens + i, json_chunk, "emissiveStrength") == 0)
+		{
+			++i;
+			out_emissive_strength->emissive_strength = cgltf_json_to_float(tokens + i, json_chunk);
+			++i;
+		}
+		else
+		{
+			i = cgltf_skip_json(tokens, i + 1);
+		}
+
+		if (i < 0)
+		{
+			return i;
+		}
+	}
+
+	return i;
+}
+
 static int cgltf_parse_json_image(cgltf_options* options, jsmntok_t const* tokens, int i, const uint8_t* json_chunk, cgltf_image* out_image)
 {
 	CGLTF_CHECK_TOKTYPE(tokens[i], JSMN_OBJECT);
@@ -4218,6 +4258,11 @@ static int cgltf_parse_json_material(cgltf_options* options, jsmntok_t const* to
 					out_material->has_sheen = 1;
 					i = cgltf_parse_json_sheen(options, tokens, i + 1, json_chunk, &out_material->sheen);
 				}
+				else if (cgltf_json_strcmp(tokens + i, json_chunk, "KHR_materials_emissive_strength") == 0)
+				{
+					out_material->has_emissive_strength = 1;
+					i = cgltf_parse_json_emissive_strength(tokens, i + 1, json_chunk, &out_material->emissive_strength);
+				}
 				else
 				{
 					i = cgltf_parse_json_unprocessed_extension(options, tokens, i, json_chunk, &(out_material->extensions[out_material->extensions_count++]));

cgltf_write.h

@@ -84,6 +84,7 @@ cgltf_size cgltf_write(const cgltf_options* options, char* buffer, cgltf_size si
 #define CGLTF_EXTENSION_FLAG_MATERIALS_VARIANTS     (1 << 10)
 #define CGLTF_EXTENSION_FLAG_MATERIALS_VOLUME       (1 << 11)
 #define CGLTF_EXTENSION_FLAG_TEXTURE_BASISU        (1 << 12)
+#define CGLTF_EXTENSION_FLAG_MATERIALS_EMISSIVE_STRENGTH (1 << 13)
 
 typedef struct {
 	char* buffer;
@@ -587,6 +588,11 @@ static void cgltf_write_material(cgltf_write_context* context, const cgltf_mater
 		context->extension_flags |= CGLTF_EXTENSION_FLAG_MATERIALS_SHEEN;
 	}
 
+	if (material->has_emissive_strength)
+	{
+		context->extension_flags |= CGLTF_EXTENSION_FLAG_MATERIALS_EMISSIVE_STRENGTH;
+	}
+
 	if (material->has_pbr_metallic_roughness)
 	{
 		const cgltf_pbr_metallic_roughness* params = &material->pbr_metallic_roughness;
@@ -603,7 +609,7 @@ static void cgltf_write_material(cgltf_write_context* context, const cgltf_mater
 		cgltf_write_line(context, "}");
 	}
 
-	if (material->unlit || material->has_pbr_specular_glossiness || material->has_clearcoat || material->has_ior || material->has_specular || material->has_transmission || material->has_sheen || material->has_volume)
+	if (material->unlit || material->has_pbr_specular_glossiness || material->has_clearcoat || material->has_ior || material->has_specular || material->has_transmission || material->has_sheen || material->has_volume || material->has_emissive_strength)
 	{
 		cgltf_write_line(context, "\"extensions\": {");
 		if (material->has_clearcoat)
@@ -695,6 +701,13 @@ static void cgltf_write_material(cgltf_write_context* context, const cgltf_mater
 		{
 			cgltf_write_line(context, "\"KHR_materials_unlit\": {}");
 		}
+		if (material->has_emissive_strength)
+		{
+			cgltf_write_line(context, "\"KHR_materials_emissive_strength\": {");
+			const cgltf_emissive_strength* params = &material->emissive_strength;
+			cgltf_write_floatprop(context, "emissiveStrength", params->emissive_strength, 1.f);
+			cgltf_write_line(context, "}");
+		}
 		cgltf_write_line(context, "}");
 	}
 
@@ -1097,6 +1110,9 @@ static void cgltf_write_extensions(cgltf_write_context* context, uint32_t extens
 	if (extension_flags & CGLTF_EXTENSION_FLAG_TEXTURE_BASISU) {
 		cgltf_write_stritem(context, "KHR_texture_basisu");
 	}
+	if (extension_flags & CGLTF_EXTENSION_FLAG_MATERIALS_EMISSIVE_STRENGTH) {
+		cgltf_write_stritem(context, "KHR_materials_emissive_strength");
+	}
 }
 
 cgltf_size cgltf_write(const cgltf_options* options, char* buffer, cgltf_size size, const cgltf_data* data)