opengl 学习(三)-----纹理

纹理就是贴图

分类
前提
demo
效果
解析

前提

需要使用一个库来处理图片：#include <stb_image.h>

https://github.com/nothings/stb

你下载好了之后，把目目录包含了就好
在这里插入图片描述
然后再引入

#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

demo

main.cpp

// 包含必要的头文件
#include <glad/glad.h>
#include <glfw3.h>#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"#include <string>
#include <fstream>
#include <sstream>
#include <iostream>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);// 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 zprogram// ------------------------------------Shader ourShader("4.2.texture.vs", "4.2.texture.fs");// set up vertex data (and buffer(s)) and configure vertex attributes// ------------------------------------------------------------------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);glBindVertexArray(VAO);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);// position attributeglVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);// color attributeglVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));glEnableVertexAttribArray(1);// texture coord attributeglVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));glEnableVertexAttribArray(2);// load and create a texture // -------------------------unsigned int texture1, texture2;// texture 1// ---------glGenTextures(1, &texture1);glBindTexture(GL_TEXTURE_2D, texture1);// set the texture wrapping parametersglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);	// set texture wrapping to GL_REPEAT (default wrapping method)glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);// set texture filtering parametersglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);// load image, create texture and generate mipmapsint width, height, nrChannels;stbi_set_flip_vertically_on_load(true); // tell stb_image.h to flip loaded texture's on the y-axis.unsigned char* data = stbi_load("container.jpg", &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);// texture 2// ---------glGenTextures(1, &texture2);glBindTexture(GL_TEXTURE_2D, texture2);// set the texture wrapping parametersglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);	// set texture wrapping to GL_REPEAT (default wrapping method)glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);// set texture filtering parametersglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);// load image, create texture and generate mipmapsdata = stbi_load("D:/vs2022/code/test_opengl_openmesh/test_opengl_openmesh/test_opengl_openmesh/awesomeface.png", &width, &height, &nrChannels, 0);if (data){glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);glGenerateMipmap(GL_TEXTURE_2D);}else{std::cout << "Failed to load texture" << std::endl;}stbi_image_free(data);// tell opengl for each sampler to which texture unit it belongs to (only has to be done once)// -------------------------------------------------------------------------------------------ourShader.use(); // don't forget to activate/use the shader before setting uniforms!// either set it manually like so:glUniform1i(glGetUniformLocation(ourShader.ID, "texture1"), 0);// or set it via the texture classourShader.setInt("texture2", 1);// render loop// -----------while (!glfwWindowShouldClose(window)){// input// -----processInput(window);// render// ------glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);// bind textures on corresponding texture unitsglActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, texture1);glActiveTexture(GL_TEXTURE1);glBindTexture(GL_TEXTURE_2D, texture2);// render containerourShader.use();glBindVertexArray(VAO);glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);// 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);glDeleteBuffers(1, &EBO);// 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);
}

4.2.texture.fs

#version 330 core
out vec4 FragColor;in vec3 ourColor;
in vec2 TexCoord;// texture samplers
uniform sampler2D texture1;
uniform sampler2D texture2;void main()
{// linearly interpolate between both textures (80% container, 20% awesomeface)FragColor = mix(texture(texture1, TexCoord), texture(texture2, TexCoord), 0.2);
}

4.2.texture.vs

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;
layout (location = 2) in vec2 aTexCoord;out vec3 ourColor;
out vec2 TexCoord;void main()
{gl_Position = vec4(aPos, 1.0);ourColor = aColor;TexCoord = vec2(aTexCoord.x, aTexCoord.y);
}