OpenGL学习笔记（八）底纹叠加

测试效果如下：

源码：
main.cpp

#include 
#include 
#include 
#include 
#include 
#include 
#include 

using namespace std;

void processInput(GLFWwindow *window) {
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);
}

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);
}

int main() {
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    GLFWwindow *window = glfwCreateWindow(400, 300, "Ebichu", NULL, NULL);
    glfwMakeContextCurrent(window);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
    gladLoadGLLoader((GLADloadproc) glfwGetProcAddress);

    fstream vfile, ffile;
    vfile.open("../OpenGL/GLSL.vs", fstream::in | fstream::out);
    ffile.open("../OpenGL/GLSL.fs", fstream::in | fstream::out);
    stringstream vstream, fstream;
    vstream << vfile.rdbuf();
    fstream << ffile.rdbuf();
    vfile.close();
    ffile.close();
    string vstring = vstream.str();
    string fstring = fstream.str();
    const char *vcode = vstring.c_str();
    const char *fcode = fstring.c_str();
    uint vertex = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex, 1, &vcode, NULL);
    glCompileShader(vertex);
    uint fragment = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragment, 1, &fcode, NULL);
    glCompileShader(fragment);
    uint ID = glCreateProgram();
    glAttachShader(ID, vertex);
    glAttachShader(ID, fragment);
    glLinkProgram(ID);
    glDeleteShader(vertex);
    glDeleteShader(fragment);

    float vertices[] = {
            //位置                 //颜色               //底纹
            +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
    };
    unsigned int indices[] = {
            0, 1, 3, // first triangle
            1, 2, 3  // second triangle
    };

    uint 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);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *) (0 * sizeof(float)));
    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);

    uint texture;
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);//s轴
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);//t轴
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);//纹理过滤方式
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);//纹理过滤方式
    int width, height, nrChannels;
    stbi_set_flip_vertically_on_load(true);
    unsigned char *data = stbi_load("../resources/textures/bricks2_disp.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);

    uint texture2;
    glGenTextures(1, &texture2);
    glBindTexture(GL_TEXTURE_2D, texture2);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);//s轴
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);//t轴
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);//纹理过滤方式
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);//纹理过滤方式
    data = stbi_load("../resources/textures/ebichu2.jpeg", &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);

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




    glBindVertexArray(VAO);

    while (!glfwWindowShouldClose(window)) {
        processInput(window);
        glClearColor(0.8f, 0.0f, 0.8f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, texture);
        glActiveTexture(GL_TEXTURE1);
        glBindTexture(GL_TEXTURE_2D, texture2);

        glUseProgram(ID);
        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;
}

顶点着色器代码：GLSL.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 = aTexCoord;
}

片段着色器代码：GLSL.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), 0.9);
}