OpenGL建立一個帶顏色的矩形
阿新 • • 發佈：2018-11-10
Shader.h
#pragma once #define GLEW_STATIC #include <GL\glew.h> #include <GLFW/glfw3.h> #include <string> #include <fstream> #include <sstream> #include <iostream> class Shader { public: Shader(const char* vertexPath, const char* fragmentPath); ~Shader(); unsigned int ID; void Shader::use(); void Shader::setBool(const std::string &name, bool value) const; void Shader::setInt(const std::string &name, int value) const; void Shader::setFloat(const std::string &name, float value) const; private: void Shader::checkCompileErrors(unsigned int shader, std::string type); };
Shader.cpp
#include "Shader.h" void Shader::use() { glUseProgram(ID); } // utility uniform functions // ------------------------------------------------------------------------ void Shader::setBool(const std::string &name, bool value) const { glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value); } // ------------------------------------------------------------------------ void Shader::setInt(const std::string &name, int value) const { glUniform1i(glGetUniformLocation(ID, name.c_str()), value); } // ------------------------------------------------------------------------ void Shader::setFloat(const std::string &name, float value) const { glUniform1f(glGetUniformLocation(ID, name.c_str()), value); } void Shader::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; } } } Shader::Shader(const char* vertexPath, const char* fragmentPath) { // 1. 從檔案路徑中獲取頂點/片段著色器 std::string vertexCode; std::string fragmentCode; std::ifstream vShaderFile; std::ifstream fShaderFile; // 保證ifstream物件可以丟擲異常： vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit); fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit); try { // 開啟檔案 vShaderFile.open(vertexPath); fShaderFile.open(fragmentPath); std::stringstream vShaderStream, fShaderStream; // 讀取檔案的緩衝內容到資料流中 vShaderStream << vShaderFile.rdbuf(); fShaderStream << fShaderFile.rdbuf(); // 關閉檔案處理器 vShaderFile.close(); fShaderFile.close(); // 轉換資料流到string vertexCode = vShaderStream.str(); fragmentCode = fShaderStream.str(); } catch (std::ifstream::failure e) { std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl; } const char* vShaderCode = vertexCode.c_str(); const char* fShaderCode = fragmentCode.c_str(); unsigned int vertex, fragment; // vertex shader vertex = glCreateShader(GL_VERTEX_SHADER); glShaderSource(vertex, 1, &vShaderCode, NULL); glCompileShader(vertex); checkCompileErrors(vertex, "VERTEX"); // fragment Shader fragment = glCreateShader(GL_FRAGMENT_SHADER); glShaderSource(fragment, 1, &fShaderCode, NULL); glCompileShader(fragment); checkCompileErrors(fragment, "FRAGMENT"); // shader Program ID = 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 necessary glDeleteShader(vertex); glDeleteShader(fragment); } Shader::~Shader() { }
main.cpp
#define GLEW_STATIC #include <GL\glew.h> #include <GLFW/glfw3.h> #include <iostream> #include "Shader.h" using namespace std; //QQ技術交流群：386476712 //terminate [ˈtɜ:mɪneɪt] 結束 終結 //hint [hɪnt] 提示 注意事項 void framebuffer_size_callback(GLFWwindow* window, int width, int height) { cout << "width : " << width << endl; glViewport(0, 0, width, height); } int main(){ //glfw初始化 //告訴glfw當前所用的OpenGL的版本號是3.3 //告訴glfw當前使用核心模式，意味著我們只能使用OpenGL功能的一個子集（沒有我們已不再需要的向後相容特性） glfwInit(); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); //使用glfw建立一個視窗 GLFWwindow* window = glfwCreateWindow(800, 600, "Hunk Xu OpenGL", NULL, NULL); if (window == NULL) { std::cout << "Failed to create GLFW window" << std::endl; glfwTerminate(); return -1; } //通知GLFW將window的上下文設定為當前執行緒的主上下文,設定主活動視窗 glfwMakeContextCurrent(window); //glew初始化 if (glewInit() != GLEW_OK){ printf("glew init failed"); glfwTerminate(); return -1; } //告訴OpenGL視口(Viewport)大小 //前兩個引數為視窗左下角位置 //後兩個引數渲染視窗的寬和高（畫素） glViewport(0, 0, 800, 600); //每當視窗調整大小時候，就呼叫這個函式 glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); float vertices[] = { 0.5f, 0.5f, 0.0f, // top right 0.5f, -0.5f, 0.0f, // bottom right -0.5f, -0.5f, 0.0f, // bottom left -0.5f, 0.5f, 0.0f // top left }; unsigned int indices[] = { // note that we start from 0! 0, 1, 3, // first Triangle 1, 2, 3 // second Triangle }; unsigned int VBO, VAO, EBO; glGenVertexArrays(1, &VAO); glGenBuffers(1, &VBO); glGenBuffers(1, &EBO); glBindVertexArray(VAO); glBindBuffer(GL_ARRAY_BUFFER, VBO);//第二個引數要設定成你想操作記憶體的標識，然後接下來的操作都是針對這一塊記憶體進行的 glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW); glVertexAttribPointer(4, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0); glEnableVertexAttribArray(4); //將頂點資料buffer和之前的繫結關係進行解綁 用於打破之前的頂點資料buffer的繫結關係 //使OpenGL的頂點資料buffer繫結狀態恢復到預設狀態。 glBindBuffer(GL_ARRAY_BUFFER, 0); //將VAO繫結到預設的VAO處，一般用於打破之前的VAO繫結關係 //使OpenGL的VAO繫結狀態恢復到預設狀態 glBindVertexArray(0); Shader* myShader = new Shader("vertexSource.txt", "fragementSource.txt"); //渲染迴圈 while (!glfwWindowShouldClose(window)){ myShader->use(); glBindVertexArray(VAO); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0); //6表示6個頂點索引 //雙緩衝(Double Buffer) //前緩衝儲存著最終輸出的影象，它會在螢幕上顯示； //而所有的的渲染指令都會在後緩衝上繪製。 //當所有的渲染指令執行完畢後，我們交換(Swap)前緩衝和後緩衝，這樣影象就立即呈顯出來 //不會出現影象閃爍的問題 glfwSwapBuffers(window); glfwPollEvents(); //輪詢使用者的輸入(鍵盤移動，滑鼠輸入) } //終止 glfwTerminate(); return 0; }
fragementSource.txt
#version 330 core
out vec4 FragColor;
in vec4 vertexColor; // 從頂點著色器傳來的輸入變數（名稱相同、型別相同）
void main()
{
FragColor = vertexColor;
}vertexSource.txt
#version 330 core
layout (location = 4) in vec3 aPos; // 位置變數的屬性位置值為0
out vec4 vertexColor; // 為片段著色器指定一個顏色輸出
void main()
{
gl_Position = vec4(aPos, 1.0); // 注意我們如何把一個vec3作為vec4的構造器的引數
vertexColor = vec4(0, 0, 1.0, 1.0); // 把輸出變數設定為暗紅色
}最後執行結果：
FR:海濤高軟（hunk Xu）
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