opengl 学习(三)-----着色器

时间:2024-03-08 13:35:40
#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 filePath std::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 files vShaderFile.open(vertexPath); fShaderFile.open(fragmentPath); std::stringstream vShaderStream, fShaderStream; // read file's buffer contents into streams vShaderStream << vShaderFile.rdbuf(); fShaderStream << fShaderFile.rdbuf(); // close file handlers vShaderFile.close(); fShaderFile.close(); // convert stream into string vertexCode = 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 shaders 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); } // 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 // colors 0.5f, -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 left 0.0f, 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 attribute glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0); glEnableVertexAttribArray(0); // color attribute glVertexAttribPointer(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 triangle ourShader.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); }