Incorporate alpha mode and cutoff (#50)

Author: karnkaul

lib/scene/include/facade/scene/material.hpp

@@ -20,6 +20,8 @@ struct TextureStore {
 
 class Material {
   public:
+	enum class AlphaMode : std::uint32_t { eOpaque = 0, eBlend, eMask };
+
 	static glm::vec4 to_linear(glm::vec4 const& srgb);
 	static glm::vec4 to_srgb(glm::vec4 const& linear);
 
@@ -49,6 +51,8 @@ class LitMaterial : public Material {
 	float roughness{0.5f};
 	std::optional<Id<Texture>> base_colour{};
 	std::optional<Id<Texture>> roughness_metallic{};
+	float alpha_cutoff{};
+	AlphaMode alpha_mode{AlphaMode::eOpaque};
 
 	void write_sets(Pipeline& pipeline, TextureStore const& store) const override;
 };

lib/scene/src/detail/gltf.hpp

@@ -1,5 +1,6 @@
 #pragma once
 #include <facade/scene/load_status.hpp>
+#include <facade/scene/material.hpp>
 #include <facade/scene/node_data.hpp>
 #include <facade/scene/transform.hpp>
 #include <facade/util/byte_buffer.hpp>
@@ -59,15 +60,15 @@ struct PbrMetallicRoughness {
 };
 
 struct Material {
-	enum class AlphaMode { eOpaque, eMask, eBlend };
+	using AlphaMode = facade::Material::AlphaMode;
 
 	std::string name{};
 	PbrMetallicRoughness pbr{};
 	std::optional<NormalTextureInfo> normal_texture{};
 	std::optional<OccusionTextureInfo> occlusion_texture{};
 	std::optional<TextureInfo> emissive_texture{};
 	glm::vec3 emissive_factor{};
-	AlphaMode alpha_mode{};
+	AlphaMode alpha_mode{AlphaMode::eOpaque};
 	float alpha_cutoff{0.5f};
 	bool double_sided{};
 };

lib/scene/src/material.cpp

@@ -6,8 +6,15 @@ namespace facade {
 namespace {
 struct Mat {
 	glm::vec4 albedo;
-	glm::vec4 metallic_roughness;
+	glm::vec4 m_r_aco_am;
 };
+
+// std::bit_cast not available on GCC 10.x
+float bit_cast_f(Material::AlphaMode const mode) {
+	auto ret = float{};
+	std::memcpy(&ret, &mode, sizeof(mode));
+	return ret;
+}
 } // namespace
 
 Texture const& TextureStore::get(std::optional<std::size_t> const index) const {
@@ -24,7 +31,7 @@ void UnlitMaterial::write_sets(Pipeline& pipeline, TextureStore const& store) co
 	auto& set2 = pipeline.next_set(2);
 	auto const mat = Mat{
 		.albedo = to_linear(tint),
-		.metallic_roughness = {},
+		.m_r_aco_am = {},
 	};
 	set2.write(0, mat);
 	pipeline.bind(set1);
@@ -38,7 +45,7 @@ void LitMaterial::write_sets(Pipeline& pipeline, TextureStore const& store) cons
 	auto& set2 = pipeline.next_set(2);
 	auto const mat = Mat{
 		.albedo = to_linear({albedo, 1.0f}),
-		.metallic_roughness = {metallic, roughness, 0.0f, 0.0f},
+		.m_r_aco_am = {metallic, roughness, alpha_cutoff, bit_cast_f(alpha_mode)},
 	};
 	set2.write(0, mat);
 	pipeline.bind(set1);

lib/scene/src/scene.cpp

@@ -59,6 +59,8 @@ std::unique_ptr<Material> to_material(gltf::Material const& material) {
 	ret->albedo = material.pbr.base_colour_factor;
 	ret->metallic = material.pbr.metallic_factor;
 	ret->roughness = material.pbr.roughness_factor;
+	ret->alpha_mode = material.alpha_mode;
+	ret->alpha_cutoff = material.alpha_cutoff;
 	if (material.pbr.base_colour_texture) { ret->base_colour = material.pbr.base_colour_texture->texture; }
 	if (material.pbr.metallic_roughness_texture) { ret->roughness_metallic = material.pbr.metallic_roughness_texture->texture; }
 	return ret;