feat: add simple transparency

destrum/include/destrum/Graphics/Material.h

@@ -29,6 +29,11 @@ enum class TextureFilteringMode : std::uint32_t {
     Anisotropic,
 };
 
+enum class BlendMode : std::uint32_t {
+    Opaque,
+    Transparent,
+};
+
 // Metallic / roughness workflow, matching glTF:
 // metallic is read from the blue channel, roughness from green and occlusion from red,
 // so a packed (occlusion)metallicRoughness texture can be used for all three slots.
@@ -59,6 +64,9 @@ struct Material {
     float normalScale{1.f};
     float occlusionStrength{1.f};
 
+    BlendMode blendMode{BlendMode::Opaque};
+    float opacity{1.f};
+
     TextureFilteringMode textureFilteringMode{TextureFilteringMode::Linear};
 
     ImageID diffuseTexture{NULL_IMAGE_ID};

destrum/include/destrum/Graphics/Pipelines/MeshPipeline.h

@@ -44,6 +44,14 @@ public:
         const IndirectDrawList& drawList,
         const IndirectDrawList::View& view);
 
+    void drawTransparent(
+        VkCommandBuffer cmd,
+        VkExtent2D renderExtent,
+        const RenderResources& resources,
+        const GPUBuffer& sceneDataBuffer,
+        const IndirectDrawList& drawList,
+        const IndirectDrawList::View& view);
+
     void cleanup(VkDevice device);
 
     void setRenderWireframe(bool wireframe) {
@@ -72,6 +80,7 @@ private:
 private:
     VkPipelineLayout m_pipelineLayout{VK_NULL_HANDLE};
     std::unique_ptr<Pipeline> m_pipeline;
+    std::unique_ptr<Pipeline> m_transparentPipeline;
     std::unique_ptr<Pipeline> m_depthPrepassPipeline;
     std::unique_ptr<Pipeline> m_selectionPrepassPipeline;
 

destrum/include/destrum/Graphics/Renderer.h

@@ -183,6 +183,7 @@ private:
 
     std::vector<MeshDrawCommand> meshDrawCommands;
     std::vector<std::size_t> sortedMeshDrawCommands;
+    std::vector<std::size_t> transparentMeshDrawCommands;
     IndirectDrawList drawList;
     DrawStats lastDrawStats;