1. 纹理贴图
wall.jpg (512×512) (learnopengl-cn.github.io)
纹理过滤分为：邻近和线性，这跟opencv图像处理一样。
多级渐远纹理
四种采样方式：
代码实现：
std_image.h
https://github.com/nothings/stb/blob/master/stb_image.h
图片
https://learnopengl-cn.github.io/img/01/06/container.jpg
main.cpp
如果load image报错等，记得增加宏：STB_IMAGE_IMPLEMENTATION
#include
#include#include#include"stb_image.h"#include #include"shader.h"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() { //1.初始化配置 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, GLFW_TRUE); #endif // __APPLE__ //2.gltf 窗口创建 GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT,"LeranOpenGL", NULL, NULL); if (window == NULL) { std::cout <<"Failed to create GLFW window"<< std::endl; glfwTerminate(); return -1; } glfwMakeContextCurrent(window); glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); //3. 加载所有GL函数指针 if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) { std::cout <<"Failed to initialize GLAD"<< std::endl; return -1; } Shader ourShader("./texture.vs","./texture.fs"); //4. 设置顶点数据 float vertices[] = { // positions // colors // texture coords 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top right 0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // bottom right -0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // bottom left -0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f // top left }; unsigned int indices[] = { 0, 1, 3, // first triangle 1, 2, 3 // second triangle }; unsigned int VBO, VAO, EBO; glGenVertexArrays(1, &VAO); glGenBuffers(1, &VBO); glGenBuffers(1,&EBO);//元素缓冲对象：Element Buffer Object，EBO glBindVertexArray(VAO); //复制顶点数组到缓冲区中供opengl使用 glBindBuffer(GL_ARRAY_BUFFER, VBO); 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); //设置顶点属性指针 glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0); glEnableVertexAttribArray(0); //设置颜色属性指针 glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float))); glEnableVertexAttribArray(1); //设置纹理属性指针 glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float))); glEnableVertexAttribArray(2); //加载和创建纹理 unsigned int texture; glGenTextures(1, &texture); glBindTexture(GL_TEXTURE_2D, texture); //设置纹理环绕参数 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); //设置纹理过滤参数 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); //加载图像和生成mipmaps int width, height, nrChannels; std::string filePath = R"(D:\CPlusProject\LearnOpenGL\DataSet\container.jpg)"; unsigned char* data = stbi_load(filePath.c_str(), &width, &height, &nrChannels, 0); if (data) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data); glGenerateMipmap(GL_TEXTURE_2D); } else { std::cout <<"Failed to load texture"<< std::endl; } stbi_image_free(data); //5. 循环渲染 while (!glfwWindowShouldClose(window)) { processInput(window); // render glClearColor(0.2f, 0.3f, 0.3f, 1.0f); glClear(GL_COLOR_BUFFER_BIT); //绑定纹理 glBindTexture(GL_TEXTURE_2D, texture); ourShader.use(); glBindVertexArray(VAO); glDrawElements(GL_TRIANGLES,6,GL_UNSIGNED_INT,0); glfwSwapBuffers(window); glfwPollEvents(); } glDeleteVertexArrays(1, &VAO); glDeleteBuffers(1, &VBO); glDeleteBuffers(1, &EBO); 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); }
2. 混合纹理 第二张图
awesomeface.png (512×512) (learnopengl-cn.github.io)
texture.vs
#version 330 core layout (location = 0) in vec3 aPos; layout (location = 1) in vec3 aColor; layout (location = 2) in vec2 aTexCorrd; out vec3 ourColor; out vec2 TexCoord; void main() { gl_Position = vec4(aPos, 1.0); ourColor = aColor; TexCoord=vec2(aTexCorrd.x,aTexCorrd.y); } texture.fs
#version 330 core out vec4 FragColor; in vec3 ourColor; in vec2 TexCoord; //texture sampler uniform sampler2D textureone; uniform sampler2D texturetwo; void main() { FragColor = mix(texture(textureone,TexCoord),texture(texturetwo,TexCoord),0.5); } main.cpp
#include#include#include#include"stb_image.h"#include #include"shader.h"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() { //1.初始化配置 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, GLFW_TRUE); #endif // __APPLE__ //2.gltf 窗口创建 GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT,"LeranOpenGL", NULL, NULL); if (window == NULL) { std::cout <<"Failed to create GLFW window"<< std::endl; glfwTerminate(); return -1; } glfwMakeContextCurrent(window); glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); //3. 加载所有GL函数指针 if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) { std::cout <<"Failed to initialize GLAD"<< std::endl; return -1; } Shader ourShader("./texture.vs","./texture.fs"); //4. 设置顶点数据 float vertices[] = { // positions // colors // texture coords 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top right 0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // bottom right -0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // bottom left -0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f // top left }; unsigned int indices[] = { 0, 1, 3, // first triangle 1, 2, 3 // second triangle }; unsigned int VBO, VAO, EBO; glGenVertexArrays(1, &VAO); glGenBuffers(1, &VBO); glGenBuffers(1,&EBO);//元素缓冲对象：Element Buffer Object，EBO glBindVertexArray(VAO); //复制顶点数组到缓冲区中供opengl使用 glBindBuffer(GL_ARRAY_BUFFER, VBO); 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); //设置顶点属性指针 glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0); glEnableVertexAttribArray(0); //设置颜色属性指针 glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float))); glEnableVertexAttribArray(1); //设置纹理属性指针 glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float))); glEnableVertexAttribArray(2); //加载和创建纹理 unsigned int textureone,texturetwo; glGenTextures(1, &textureone); glBindTexture(GL_TEXTURE_2D, textureone); //设置纹理环绕参数 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); //设置纹理过滤参数 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); //加载图像和生成mipmaps int width, height, nrChannels; stbi_set_flip_vertically_on_load(true); std::string filePath = R"(D:\CPlusProject\LearnOpenGL\DataSet\container.jpg)"; unsigned char* data = stbi_load(filePath.c_str(), &width, &height, &nrChannels, 0); if (data) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data); glGenerateMipmap(GL_TEXTURE_2D); } else { std::cout <<"Failed to load texture"<< std::endl; } stbi_image_free(data); glGenTextures(1, &texturetwo); glBindTexture(GL_TEXTURE_2D, texturetwo); //设置纹理环绕参数 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); //设置纹理过滤参数 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); //加载图像和生成mipmaps filePath = R"(D:\CPlusProject\LearnOpenGL\DataSet\awesomeface.png)"; unsigned char* data2 = stbi_load(filePath.c_str(), &width, &height, &nrChannels, 0); if (data2) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data2); glGenerateMipmap(GL_TEXTURE_2D); } else { std::cout <<"Failed to load texture"<< std::endl; } stbi_image_free(data2); ourShader.use(); glUniform1i(glGetUniformLocation(ourShader.ID,"textureone"), 0);//二选一 ourShader.setInt("texturetwo", 1);//二选一 //5. 循环渲染 while (!glfwWindowShouldClose(window)) { processInput(window); // render glClearColor(0.2f, 0.3f, 0.3f, 1.0f); glClear(GL_COLOR_BUFFER_BIT); //绑定纹理 glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, textureone); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texturetwo); ourShader.use(); glBindVertexArray(VAO); glDrawElements(GL_TRIANGLES,6,GL_UNSIGNED_INT,0); glfwSwapBuffers(window); glfwPollEvents(); } glDeleteVertexArrays(1, &VAO); glDeleteBuffers(1, &VBO); glDeleteBuffers(1, &EBO); 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); } 
