GLSL着色器

1|0uniform

顶点着色器的输出out和片段着色器的输入in变量名一样的话可以由链接器将他们连接起来。
uniform是全局的，变量名必须独一无二，它允许cpu向gpu传数据，要先useShaderProgram才能更改uniform的值，在更改之前要获得位置，获得位置可以在useprogram之前。

2|0顶点包含多个属性

在顶点加颜色值，顶点pointer那里的初始地址、size、偏移都需要改，激活顶点的位置为1

#include<glad/glad.h>
#include<GLFW/glfw3.h>
#include<iostream>
const char *vertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 aPos;\n"
"layout (location = 1) in vec3 aColor;\n"
"out vec4 color;"
"void main()\n"
"{\n"
"   color = vec4(aColor, 1.0);\n"
"   gl_Position = vec4(aPos, 1.0);\n"
"}\0";
const char *fragmentShaderSource = "#version 330 core\n"
"out vec4 FragColor;"
"in vec4 color;"
"void main()\n"
"{\n"
"	FragColor = color;"
"}\0";
void framebuffer_size_callback(GLFWwindow* window, int width, int height) 
{
	glViewport(0, 0, width, height);
}
void processInput(GLFWwindow* window)
{
	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
		glfwSetWindowShouldClose(window, true);
}
int main()
{
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	//创建窗口对象
	GLFWwindow* window = glfwCreateWindow(800, 600, "LearnOpenGL", NULL, NULL);
	if (window == NULL)
	{
		std::cout << "Failed to create" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);
	//初始化GLAD管理指针，加载系统OpenGL函数指针
	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{
		std::cout << "Failed to init GLAD" << std::endl;
		return -1;
	}
	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
	//shader
	unsigned int vertexShader;
	vertexShader = glCreateShader(GL_VERTEX_SHADER);
	glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
	glCompileShader(vertexShader);
	unsigned int fragmentShader;
	fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
	glCompileShader(fragmentShader);
	unsigned int shaderProgram;
	shaderProgram = glCreateProgram();
	glAttachShader(shaderProgram, vertexShader);
	glAttachShader(shaderProgram, fragmentShader);
	glLinkProgram(shaderProgram);
	glDeleteShader(vertexShader);
	glDeleteShader(fragmentShader);

	float vertices[] = {
		 0.5f,  0.5f, 0.0f,  1.0f, 0.0f, 0.0f,//右上 
		 0.5f, -0.5f, 0.0f,	 0.0f, 1.0f, 0.0f,//右下
		-0.5f,  0.5f, 0.0f,	 0.0f, 0.0f, 1.0f,//左上
		-0.5f, -0.5f, 0.0f,  1.0f, 1.0f, 1.0f,//左下
	};
	int indice[] = {
		0, 1, 2,
		2, 3, 1
	};
	unsigned int VBO, VAO, EBO;
	glGenBuffers(1, &VBO);
	glGenBuffers(1, &EBO);
	glGenVertexArrays(1, &VAO);
	glBindVertexArray(VAO);
	glBindBuffer(GL_ARRAY_BUFFER, VBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);	//第一个是类型，第二个是大小，第三个是数据
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indice), indice, GL_STATIC_DRAW);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
	glEnableVertexAttribArray(1);
	while (!glfwWindowShouldClose(window))
	{
		processInput(window);
		glClearColor(0.0f, 0.5f, 1.0f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT);
		glUseProgram(shaderProgram);
		glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
		glfwSwapBuffers(window);
		glfwPollEvents();
	}
	glDeleteBuffers(1, &VBO);
	glDeleteProgram(shaderProgram);
	//关闭窗口
	glfwTerminate();
	return 0;
}

3|0分开文件

先把VS中include的范围加入项目目录
把顶点着色器命名为shader.vs，像素着色器命名为shader.fs
在Shader里面，构造函数用流加载两个shader，注意要写调试信息，然后再实例化use函数，再main函数里面好用
main里面就可以用Shader类直接加载

shader.vs

#version 330 core
layout (location=0) in vec3 aPos;
layout (location=1) in vec3 aColor;

out vec4 color;

void main()
{
	gl_Position = vec4(aPos, 1.0f);
	color = vec4(aColor, 1.0f);
}

shader.fs

#version 330 core
in vec4 color;
out vec4 fragColor;
void main()
{
	fragColor = color;
}

shader.cpp

#ifndef SHADER_H
#endif SHADER_H

#include<glad/glad.h>
#include<string>
#include<fstream>
#include<sstream>
#include<iostream>

class Shader
{
public:
	unsigned int ID;
	Shader(const char* vertexPath, const char* fragmentPath)
	{
		using namespace std;
		string vertexCode;
		string fragmentCode;
		ifstream vShaderFile;
		ifstream fShaderFile;
		vShaderFile.exceptions(ifstream::failbit | ifstream::badbit);
		fShaderFile.exceptions(ifstream::failbit | ifstream::badbit);
		try
		{
			vShaderFile.open(vertexPath);
			fShaderFile.open(fragmentPath);
			stringstream vShaderStream, fShaderStream;
			vShaderStream << vShaderFile.rdbuf();
			fShaderStream << fShaderFile.rdbuf();
			vShaderFile.close();
			fShaderFile.close();
			vertexCode = vShaderStream.str();
			fragmentCode = fShaderStream.str();
		}
		catch (ifstream::failure e)
		{
			cout << "ERROR::SHADER::FILE_NOT_SUCCESSFULLY_READ" << endl;
		}
		const char* vShaderCode = vertexCode.c_str();
		const char* fShaderCode = fragmentCode.c_str();
		unsigned int vertexShader, fragmentShader;
		vertexShader = glCreateShader(GL_VERTEX_SHADER);
		glShaderSource(vertexShader, 1, &vShaderCode, NULL);
		glCompileShader(vertexShader);
		int success;
		char infolog[512];
		glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
		if (!success)
		{
			glGetShaderInfoLog(vertexShader, 512, NULL, infolog);
			cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infolog << endl;
		}
		fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
		glShaderSource(fragmentShader, 1, &fShaderCode, NULL);
		glCompileShader(fragmentShader);
		glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
		if (!success)
		{
			glGetShaderInfoLog(fragmentShader, 512, NULL, infolog);
			cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infolog << endl;
		}
		ID = glCreateProgram();
		glAttachShader(ID, vertexShader);
		glAttachShader(ID, fragmentShader);
		glLinkProgram(ID);
		glGetProgramiv(ID, GL_LINK_STATUS, &success);
		if (!success)
		{
			glGetProgramInfoLog(ID, 512, NULL, infolog);
			cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infolog << endl;
		}
		glDeleteShader(vertexShader);
		glDeleteShader(fragmentShader);
	}
	void use()
	{
		glUseProgram(ID);
	}
};

main.cpp

#include<glad/glad.h>
#include<GLFW/glfw3.h>
#include<iostream>
#include<Shader.cpp>
void framebuffer_size_callback(GLFWwindow* window, int width, int height) 
{
	glViewport(0, 0, width, height);
}
void processInput(GLFWwindow* window)
{
	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
		glfwSetWindowShouldClose(window, true);
}
int main()
{
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	//创建窗口对象
	GLFWwindow* window = glfwCreateWindow(800, 600, "LJHyyds", NULL, NULL);
	if (window == NULL)
	{
		std::cout << "Failed to create" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);
	//初始化GLAD管理指针，加载系统OpenGL函数指针
	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{
		std::cout << "Failed to init GLAD" << std::endl;
		return -1;
	}
	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
	Shader myshader("shader.vs", "shader.fs");
	float vertices[] = {
		 0.5f,  0.5f, 0.0f,  1.0f, 0.0f, 0.0f,//右上 
		 0.5f, -0.5f, 0.0f,	 0.0f, 1.0f, 0.0f,//右下
		-0.5f,  0.5f, 0.0f,	 0.0f, 0.0f, 1.0f,//左上
	};
	unsigned int VBO, VAO;
	glGenBuffers(1, &VBO);
	glGenVertexArrays(1, &VAO);
	glBindVertexArray(VAO);
	glBindBuffer(GL_ARRAY_BUFFER, VBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);	//第一个是类型，第二个是大小，第三个是数据
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
	glEnableVertexAttribArray(1);
	while (!glfwWindowShouldClose(window))
	{
		processInput(window);
		glClearColor(0.0f, 0.5f, 1.0f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT);
		myshader.use();
		glDrawArrays(GL_TRIANGLES, 0, 3);
		glfwSwapBuffers(window);
		glfwPollEvents();
	}
	glDeleteVertexArrays(1, &VAO);
	glDeleteBuffers(1, &VBO);
	//关闭窗口
	glfwTerminate();
	return 0;
}

4|0纪念

终于做到了梦想中的写shader，太高兴了

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__EOF__

本文作者：Liujiahang
本文链接：https://www.cnblogs.com/IamIron-Man/p/16601916.html
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