1 files changed, 180 insertions, 0 deletions
diff --git a/src/brussel.engine/Shader.hpp b/src/brussel.engine/Shader.hpp
new file mode 100644
index 0000000..cb980cd
--- /dev/null
+++ b/src/brussel.engine/Shader.hpp
@@ -0,0 +1,180 @@
+#pragma once
+
+#include "GraphicsTags.hpp"
+#include "Ires.hpp"
+#include "RcPtr.hpp"
+#include "Utils.hpp"
+
+#include <glad/glad.h>
+#include <robin_hood.h>
+#include <json_dto/pub.hpp>
+#include <memory>
+#include <string_view>
+#include <variant>
+#include <vector>
+
+// TODO move to variable after pattern matching is in the language
+
+// Forward declarations
+class Shader;
+class IresShader;
+
+struct ShaderMathVariable {
+	std::string name;
+	GLuint location;
+	Tags::VertexElementSemantic semantic = Tags::VES_Generic;
+	GLenum scalarType;
+	int width;
+	int height;
+	int arrayLength = 1;
+
+	void ShowInfo() const;
+
+	template <typename TJsonIo>
+	void json_io(TJsonIo& io) {
+		io& json_dto::mandatory("Name", name);
+		io& json_dto::mandatory("Semantic", static_cast<int>(semantic));
+		io& json_dto::mandatory("ScalarType", scalarType);
+		io& json_dto::mandatory("Width", width);
+		io& json_dto::mandatory("Height", height);
+		io& json_dto::optional("ArrayLength", arrayLength, 1);
+	}
+};
+
+struct ShaderSamplerVariable {
+	std::string name;
+	GLuint location;
+	Tags::VertexElementSemantic semantic = Tags::VES_Generic;
+	GLenum samplerType;
+	int arrayLength = 1;
+
+	void ShowInfo() const;
+
+	template <typename TJsonIo>
+	void json_io(TJsonIo& io) {
+		io& json_dto::mandatory("Name", name);
+		io& json_dto::mandatory("Semantic", static_cast<int>(semantic));
+		io& json_dto::mandatory("SamplerType", samplerType);
+		io& json_dto::optional("ArrayLength", arrayLength, 1);
+	}
+};
+
+struct ShaderThingId {
+	enum Kind {
+		KD_Input,
+		KD_Output,
+		KD_Uniform,
+	};
+
+	Kind kind;
+	int index;
+};
+
+struct ShaderInfo {
+	robin_hood::unordered_map<std::string, ShaderThingId, StringHash, StringEqual> things;
+	std::vector<ShaderMathVariable> inputs;
+	std::vector<ShaderMathVariable> outputs;
+	std::vector<std::variant<ShaderMathVariable, ShaderSamplerVariable>> uniforms;
+
+	// Find the first variable with the matching semantic
+	GLuint FindInputLocation(Tags::VertexElementSemantic semantic);
+	GLuint FindOutputLocation(Tags::VertexElementSemantic semantic);
+
+	template <typename TJsonIo>
+	void json_io(TJsonIo& io) {
+		io& json_dto::mandatory("Inputs", inputs);
+		io& json_dto::mandatory("Outputs", outputs);
+		// TODO make json_dto support std::variant
+//		io& json_dto::mandatory("Uniforms", uniforms);
+	}
+};
+
+class Shader : public RefCounted {
+	friend class IresShader;
+
+private:
+	IresShader* mIres = nullptr;
+	ShaderInfo mInfo;
+	GLuint mProgram = 0;
+
+public:
+	GLuint autofill_Transform = Tags::kInvalidLocation;
+	GLuint autofill_Time = Tags::kInvalidLocation;
+	GLuint autofill_DeltaTime = Tags::kInvalidLocation;
+	GLuint autofill_TextureAtlas = Tags::kInvalidLocation;
+
+public:
+	Shader();
+	~Shader();
+	Shader(const Shader&) = delete;
+	Shader& operator=(const Shader&) = delete;
+	Shader(Shader&&) = default;
+	Shader& operator=(Shader&&) = default;
+
+	enum ErrorCode {
+		EC_Success,
+		/// Generated when Init*() functions are called on an already initialized Shader object.
+		EC_AlreadyInitialized,
+		/// Generated when the one-source-file text contains invalid or duplicate shader variants.
+		EC_InvalidShaderVariant,
+		EC_FileIoFailed,
+		EC_CompilationFailed,
+		EC_LinkingFailed,
+	};
+
+	struct ShaderSources {
+		std::string_view vertex;
+		std::string_view geometry;
+		std::string_view tessControl;
+		std::string_view tessEval;
+		std::string_view fragment;
+	};
+
+	/// Create shader by compiling each shader source file separately and then combining them together
+	/// into a Shader object.
+	ErrorCode InitFromSources(const ShaderSources& sources);
+
+	/// The given text will be split into different shader sections according to #type directives,
+	/// and combined to form a Shader object.
+	/// For OpenGL, this process involves compililng each section separately and then linking them
+	/// together.
+	///
+	/// There are a directive for each shader type
+	/// - `#type vertex`: Vertex shader
+	/// - `#type geometry`: Geometry shader
+	/// - `#type tessellation_control`: Tessellation control shader
+	/// - `#type tessellation_evaluation`: Tessellation evaluation shader
+	/// - `#type fragment`: Fragment shader
+	ErrorCode InitFromSource(std::string_view source);
+
+	/// Rebuild info object using OpenGL shader introspection API. Requires OpenGL 4.3 or above. Overrides existing info object.
+	bool GatherInfoShaderIntrospection();
+	const ShaderInfo& GetInfo() const { return mInfo; }
+	ShaderInfo& GetInfo() { return mInfo; }
+	/// If not empty, this name must not duplicate with any other shader object in the process.
+	GLuint GetProgram() const { return mProgram; }
+
+	IresShader* GetIres() const { return mIres; }
+
+	bool IsValid() const;
+};
+
+// Initialized in main()
+inline RcPtr<Shader> gDefaultShader;
+
+class IresShader : public IresObject {
+private:
+	RcPtr<Shader> mInstance;
+	std::string mSourceFile;
+
+public:
+	IresShader();
+
+	Shader* GetInstance() const;
+	void InvalidateInstance();
+
+	void ShowEditor(IEditor& editor) override;
+
+	void Write(IresWritingContext& ctx, rapidjson::Value& value, rapidjson::Document& root) const override;
+	void Read(IresLoadingContext& ctx, const rapidjson::Value& value) override;
+};