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 <glad/glad.h>
#include <GLFW/glfw3.h>#include <iostream>
#include "stb_image.h"
#include <cmath>
#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 coords0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top right0.5f, -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 triangle1, 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mipmapsint 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);// renderglClearColor(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 <glad/glad.h>
#include <GLFW/glfw3.h>#include <iostream>
#include "stb_image.h"
#include <cmath>
#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 coords0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top right0.5f, -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 triangle1, 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mipmapsint 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mipmapsfilePath = 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);// renderglClearColor(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);
}