opengl 学习(三)-----着色器

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OPengl C++

demo

#include "glad/glad.h"
#include "glfw3.h"
#include <iostream>
#include <cmath>
#include <vector>#include <string>
#include <fstream>
#include <sstream>using namespace std;/******************************************************/
class Shader
{
public:unsigned int ID;// constructor generates the shader on the fly// ------------------------------------------------------------------------Shader(const char* vertexPath, const char* fragmentPath){// 1. retrieve the vertex/fragment source code from filePathstd::string vertexCode;std::string fragmentCode;std::ifstream vShaderFile;std::ifstream fShaderFile;// ensure ifstream objects can throw exceptions:vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);try{// open filesvShaderFile.open(vertexPath);fShaderFile.open(fragmentPath);std::stringstream vShaderStream, fShaderStream;// read file's buffer contents into streamsvShaderStream << vShaderFile.rdbuf();fShaderStream << fShaderFile.rdbuf();// close file handlersvShaderFile.close();fShaderFile.close();// convert stream into stringvertexCode = vShaderStream.str();fragmentCode = fShaderStream.str();}catch (std::ifstream::failure& e){std::cout << "ERROR::SHADER::FILE_NOT_SUCCESSFULLY_READ: " << e.what() << std::endl;}const char* vShaderCode = vertexCode.c_str();const char* fShaderCode = fragmentCode.c_str();// 2. compile shadersunsigned int vertex, fragment;// vertex shadervertex = glCreateShader(GL_VERTEX_SHADER);glShaderSource(vertex, 1, &vShaderCode, NULL);glCompileShader(vertex);checkCompileErrors(vertex, "VERTEX");// fragment Shaderfragment = glCreateShader(GL_FRAGMENT_SHADER);glShaderSource(fragment, 1, &fShaderCode, NULL);glCompileShader(fragment);checkCompileErrors(fragment, "FRAGMENT");// shader ProgramID = glCreateProgram();glAttachShader(ID, vertex);glAttachShader(ID, fragment);glLinkProgram(ID);checkCompileErrors(ID, "PROGRAM");// delete the shaders as they're linked into our program now and no longer necessaryglDeleteShader(vertex);glDeleteShader(fragment);}// activate the shader// ------------------------------------------------------------------------void use(){glUseProgram(ID);}// utility uniform functions// ------------------------------------------------------------------------void setBool(const std::string& name, bool value) const{glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value);}// ------------------------------------------------------------------------void setInt(const std::string& name, int value) const{glUniform1i(glGetUniformLocation(ID, name.c_str()), value);}// ------------------------------------------------------------------------void setFloat(const std::string& name, float value) const{glUniform1f(glGetUniformLocation(ID, name.c_str()), value);}private:// utility function for checking shader compilation/linking errors.// ------------------------------------------------------------------------void checkCompileErrors(unsigned int shader, std::string type){int success;char infoLog[1024];if (type != "PROGRAM"){glGetShaderiv(shader, GL_COMPILE_STATUS, &success);if (!success){glGetShaderInfoLog(shader, 1024, NULL, infoLog);std::cout << "ERROR::SHADER_COMPILATION_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;}}else{glGetProgramiv(shader, GL_LINK_STATUS, &success);if (!success){glGetProgramInfoLog(shader, 1024, NULL, infoLog);std::cout << "ERROR::PROGRAM_LINKING_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;}}}
};
/******************************************************/void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;int main()
{// glfw: initialize and configure// ------------------------------glfwInit();glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);#ifdef __APPLE__glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif// glfw window creation// --------------------GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);if (window == NULL){std::cout << "Failed to create GLFW window" << std::endl;glfwTerminate();return -1;}glfwMakeContextCurrent(window);glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);// glad: load all OpenGL function pointers// ---------------------------------------if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)){std::cout << "Failed to initialize GLAD" << std::endl;return -1;}// build and compile our shader program// ------------------------------------Shader ourShader("3.3.shader.vs", "3.3.shader.fs"); // you can name your shader files however you like// set up vertex data (and buffer(s)) and configure vertex attributes// ------------------------------------------------------------------float vertices[] = {// positions         // colors0.5f, -0.5f, 0.0f,  1.0f, 0.0f, 0.0f,  // bottom right-0.5f, -0.5f, 0.0f,  0.0f, 1.0f, 0.0f,  // bottom left0.0f,  0.5f, 0.0f,  0.0f, 0.0f, 1.0f   // top };unsigned int VBO, VAO;glGenVertexArrays(1, &VAO);glGenBuffers(1, &VBO);// bind the Vertex Array Object first, then bind and set vertex buffer(s), and then configure vertex attributes(s).glBindVertexArray(VAO);glBindBuffer(GL_ARRAY_BUFFER, VBO);glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);// position attributeglVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);// color attributeglVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));glEnableVertexAttribArray(1);// You can unbind the VAO afterwards so other VAO calls won't accidentally modify this VAO, but this rarely happens. Modifying other// VAOs requires a call to glBindVertexArray anyways so we generally don't unbind VAOs (nor VBOs) when it's not directly necessary.// glBindVertexArray(0);// render loop// -----------while (!glfwWindowShouldClose(window)){// input// -----processInput(window);// render// ------glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);// render the triangleourShader.use();glBindVertexArray(VAO);glDrawArrays(GL_TRIANGLES, 0, 3);// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)// -------------------------------------------------------------------------------glfwSwapBuffers(window);glfwPollEvents();}// optional: de-allocate all resources once they've outlived their purpose:// ------------------------------------------------------------------------glDeleteVertexArrays(1, &VAO);glDeleteBuffers(1, &VBO);// glfw: terminate, clearing all previously allocated GLFW resources.// ------------------------------------------------------------------glfwTerminate();return 0;
}// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow* window)
{if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)glfwSetWindowShouldClose(window, true);
}// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{// make sure the viewport matches the new window dimensions; note that width and // height will be significantly larger than specified on retina displays.glViewport(0, 0, width, height);
}

• 3.3.shader.vs

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;out vec3 ourColor;void main()
{gl_Position = vec4(aPos, 1.0);ourColor = aColor;
}

• 3.3.shader.fs

#version 330 core
out vec4 FragColor;in vec3 ourColor;void main()
{FragColor = vec4(ourColor, 1.0f);
}

效果

解析

教程

https://learnopengl-cn.github.io/01%20Getting%20started/05%20Shaders/