opengl日记10-opengl使用多个纹理示例

环境

• 系统：ubuntu20.04
• opengl版本：4.6
• glfw版本：3.3
• glad版本：4.6
• cmake版本：3.16.3
• gcc版本：10.3.0

在<opengl学习日记9-opengl使用纹理示例>的基础上，拓展使用多个纹理。

代码

CMakeLists.txt文件内容不变。

fragmentShaderSource.fs

#version 330 core
out vec4 FragColor;in vec3 ourColor;
in vec2 TexCoord;uniform sampler2D texture1;
uniform sampler2D texture2;void main()
{FragColor = mix(texture(texture1,TexCoord),texture(texture2,TexCoord),0.2) ;
}

vertexShaderSource.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);
}

main.cpp

#include <glad/glad.h>
#include <GLFW/glfw3.h>#include "stbimage.h"//#include <glm/glm.hpp>
//#include <glm/gtc/matrix_transform.hpp>
//#include <glm/gtc/type_ptr.hpp>#include <iostream>
#include <fstream>
#include <iosfwd>
#include <sstream>
#include <string>//定义窗口大小
int SCR_WIDTH = 800;
int SCR_HEIGHT = 600;std::string readFile(const std::string filename)
{std::string data;data = readFile(filename.c_str());return data;
}std::string readFile(const char* filename)
{std::string data;std::ifstream infile;infile.open(filename);std::stringstream neirong;neirong << infile.rdbuf();infile.close();data = neirong.str();return data;
}int main()
{std::cout << "Hello World!" << std::endl;std::cout << "初始化" << std::endl;glfwInit();glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);GLFWwindow *window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "transformtions", NULL, NULL);if (window == NULL) {std::cout << "创建窗口失败" << std::endl;return -1;}glfwMakeContextCurrent(window);if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {std::cout << "初始化glad失败" << std::endl;return -1;}std::cout << "顶点定义，VAO，VBO，EBO" << std::endl;float vertices[] = {0.5f, 0.5f, 0.0f,    1.0f, 0.0f, 0.0f,  1.0f, 1.0f,0.5f, -0.5f, 0.0f,   0.0f, 1.0f, 0.0f,  1.0f, 0.0f,-0.5f, -0.5f, 0.0f,  0.0f, 0.0f, 1.0f,  0.0f, 0.0f,-0.5f, 0.5f, 0.0f,   1.0f, 1.0f, 0.0f,   0.0f, 1.0f};//索引缓冲区unsigned int indices[] = {0, 1, 3,1, 2, 3};unsigned int VAO, VBO, 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);//定位点关系glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *) 0);glEnableVertexAttribArray(0);glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *) (3 * sizeof(float)));glEnableVertexAttribArray(1);glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *) (6 * sizeof(float)));glEnableVertexAttribArray(2);std::cout << "着色器定义" << std::endl;std::cout << "着色器定义:顶点着色器" << std::endl;std::string vertexShaderSource = readFile("vertexShaderSource.vs");const char *vertexShaderSourceCtr = vertexShaderSource.c_str();unsigned int vertexShader;vertexShader = glCreateShader(GL_VERTEX_SHADER);glShaderSource(vertexShader, 1, &vertexShaderSourceCtr, NULL);glCompileShader(vertexShader);int success;char infolog[512] = {0};glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);if (!success) {glGetShaderInfoLog(vertexShader, 512, NULL, infolog);std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infolog << std::endl;}std::cout << "着色器定义:片段着色器" << std::endl;std::string fragmentShaderSource = readFile("fragmentShaderSource.fs");const char *fragmentShaderSourceCtr = fragmentShaderSource.c_str();unsigned int fragmentShader;fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);glShaderSource(fragmentShader, 1, &fragmentShaderSourceCtr, NULL);glCompileShader(fragmentShader);glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);if (!success) {glGetShaderInfoLog(fragmentShader, 512, NULL, infolog);std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infolog << std::endl;}std::cout << "着色器定义:启用着色器程序" << std::endl;unsigned int shaderProgram;shaderProgram = glCreateProgram();glAttachShader(shaderProgram, vertexShader);glAttachShader(shaderProgram, fragmentShader);glLinkProgram(shaderProgram);glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);if (!success) {glGetProgramInfoLog(shaderProgram, 512, NULL, infolog);std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infolog << std::endl;}glDeleteShader(vertexShader);glDeleteShader(fragmentShader);std::cout << "纹理定义" << std::endl;unsigned int texture1;glGenTextures(1, &texture1);glBindTexture(GL_TEXTURE_2D, texture1);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);stbi_set_flip_vertically_on_load(true);std::cout << "读取纹理图片" << std::endl;int width, height, nrChannels;unsigned char* texturesData = stbi_load("container.jpg", &width, &height, &nrChannels, 0);if (texturesData) {//绑定和纹理图片数据结合glTexImage2D(GL_TEXTURE_2D,0,GL_RGB,width,height,0,GL_RGB,GL_UNSIGNED_BYTE,texturesData);glGenerateMipmap(GL_TEXTURE_2D);} else {std::cout << "读取图片数据错误" << std::endl;}stbi_image_free(texturesData);std::cout << "纹理定义2" << std::endl;unsigned int texture2;glGenTextures(1, &texture2);glBindTexture(GL_TEXTURE_2D, texture2);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);std::cout << "读取纹理图片" << std::endl;//        int width, height, nrChannels;texturesData = stbi_load("awesomeface.png", &width, &height, &nrChannels, 0);if (texturesData) {//绑定和纹理图片数据结合glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,width,height,0,GL_RGBA,GL_UNSIGNED_BYTE,texturesData);glGenerateMipmap(GL_TEXTURE_2D);} else {std::cout << "读取图片数据错误" << std::endl;}stbi_image_free(texturesData);glUseProgram(shaderProgram);glUniform1i(glGetUniformLocation((GLuint)shaderProgram,"texture1"),0);glUniform1i(glGetUniformLocation((GLuint)shaderProgram,"texture2"),1);std::cout << "绘制" << std::endl;while (!glfwWindowShouldClose(window)) {glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);glActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, texture1);glActiveTexture(GL_TEXTURE1);glBindTexture(GL_TEXTURE_2D, texture2);glUseProgram(shaderProgram);glBindVertexArray(VAO);glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, (const GLvoid *) 0);glfwSwapBuffers(window);glfwPollEvents();}std::cout << "内存释放" << std::endl;glDeleteVertexArrays(1, &VAO);glDeleteBuffers(1, &VBO);glDeleteBuffers(1, &EBO);glDeleteProgram(shaderProgram);glfwTerminate();return 0;
}

总结

1. 使用多个纹理，则需要定义多个纹理，读取多个图片数据

std::cout << "纹理定义" << std::endl;unsigned int texture1;glGenTextures(1, &texture1);glBindTexture(GL_TEXTURE_2D, texture1);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);stbi_set_flip_vertically_on_load(true);std::cout << "读取纹理图片" << std::endl;int width, height, nrChannels;unsigned char* texturesData = stbi_load("container.jpg", &width, &height, &nrChannels, 0);if (texturesData) {//绑定和纹理图片数据结合glTexImage2D(GL_TEXTURE_2D,0,GL_RGB,width,height,0,GL_RGB,GL_UNSIGNED_BYTE,texturesData);glGenerateMipmap(GL_TEXTURE_2D);} else {std::cout << "读取图片数据错误" << std::endl;}stbi_image_free(texturesData);std::cout << "纹理定义2" << std::endl;unsigned int texture2;glGenTextures(1, &texture2);glBindTexture(GL_TEXTURE_2D, texture2);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);std::cout << "读取纹理图片" << std::endl;//        int width, height, nrChannels;texturesData = stbi_load("awesomeface.png", &width, &height, &nrChannels, 0);if (texturesData) {//绑定和纹理图片数据结合glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,width,height,0,GL_RGBA,GL_UNSIGNED_BYTE,texturesData);glGenerateMipmap(GL_TEXTURE_2D);} else {std::cout << "读取图片数据错误" << std::endl;}stbi_image_free(texturesData);

2. 一张图片纹理叠加在另一张图片纹理上，需要有透明通道，图片格式是png，所以在绑定png纹理图片是需要注意参数变化

glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,width,height,0,GL_RGBA,GL_UNSIGNED_BYTE,texturesData);

注意第三个参数和第七个参数，由GL_RGB变为GL_RGBA
3. 在绘制之前需要手动设置一次纹理对应的采样器

glUseProgram(shaderProgram);
glUniform1i(glGetUniformLocation((GLuint)shaderProgram,"texture1"),0);
glUniform1i(glGetUniformLocation((GLuint)shaderProgram,"texture2"),1);

这里需要注意，glUniform1i函数的书写是数字1，不是字母l
4. 在读取纹理之前，设置一下，可保持加载图像不上下颠倒

stbi_set_flip_vertically_on_load(true);