From e66286ebe30afc9acc4531fc2bea29b7fb924f93 Mon Sep 17 00:00:00 2001
From: rtk0c <mail.tianyig@gmail.com>
Date: Mon, 30 May 2022 17:03:20 -0700
Subject: Changeset: 56 Buildsystem cleanup: change to layered structure for
 different targets

---
 source/30-game/Shader.hpp | 173 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 173 insertions(+)
 create mode 100644 source/30-game/Shader.hpp

(limited to 'source/30-game/Shader.hpp')

diff --git a/source/30-game/Shader.hpp b/source/30-game/Shader.hpp
new file mode 100644
index 0000000..707e6cc
--- /dev/null
+++ b/source/30-game/Shader.hpp
@@ -0,0 +1,173 @@
+#pragma once
+
+#include "GraphicsTags.hpp"
+#include "Ires.hpp"
+#include "RcPtr.hpp"
+#include "Utils.hpp"
+
+#include <glad/glad.h>
+#include <robin_hood.h>
+#include <memory>
+#include <string_view>
+#include <vector>
+
+// TODO move to variable after pattern matching is in the language
+
+// Forward declarations
+class Shader;
+class IresShader;
+
+struct ShaderVariable {
+	enum Kind {
+		KD_Math,
+		KD_Sampler,
+	};
+
+	std::string name;
+	Kind kind;
+	GLuint location;
+	Tags::VertexElementSemantic semantic = Tags::VES_Generic;
+
+	virtual void ShowInfo() const = 0;
+
+protected:
+	ShaderVariable(Kind kind)
+		: kind{ kind } {}
+};
+
+struct ShaderMathVariable : public ShaderVariable {
+	GLenum scalarType;
+	int arrayLength;
+	int width;
+	int height;
+
+	ShaderMathVariable()
+		: ShaderVariable(KD_Math) {}
+
+	virtual void ShowInfo() const override;
+};
+
+struct ShaderSamplerVariable : public ShaderVariable {
+	GLenum type;
+	int arrayLength;
+
+	ShaderSamplerVariable()
+		: ShaderVariable(KD_Sampler) {}
+
+	virtual void ShowInfo() const override;
+};
+
+struct ShaderThingId {
+	enum Kind {
+		KD_Input,
+		KD_Output,
+		KD_Uniform,
+		KD_Invalid,
+	};
+
+	Kind kind = KD_Invalid;
+	int index = 0;
+
+	bool IsValid() const;
+};
+
+struct ShaderInfo {
+	robin_hood::unordered_map<std::string, ShaderThingId, StringHash, StringEqual> things;
+	std::vector<ShaderMathVariable> inputs;
+	std::vector<ShaderMathVariable> outputs;
+	std::vector<std::unique_ptr<ShaderVariable>> uniforms;
+
+	GLuint FindInputLocation(Tags::VertexElementSemantic semantic);
+	GLuint FindOutputLocation(Tags::VertexElementSemantic semantic);
+	ShaderVariable* FindVariable(const ShaderThingId& thing);
+};
+
+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;
+};
-- 
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