tex2glad.cpp

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <math.h>
#include <iostream>
const unsigned int SCR_WIDTH = 800, SCR_HEIGHT = 600;
const char *vertexShaderSource = "#version 330 core\n"
    "layout (location = 0) in vec3 aPos;\n"
    "layout (location = 1) in vec3 aColor;\n"
    "out vec3 ourColor;\n"
    "uniform vec3 aOfs;\n"
    "void main(){\n"
//    "   gl_Position = vec4(aOfs.x + aPos.x, -aPos.y, aPos.z, 1.0);\n"
    "   gl_Position = vec4(aPos.x, -aPos.y, aPos.z, 1.0);\n"
    "   ourColor = aColor + aOfs;\n"
//    "   ourColor = aPos;\n"
    "}";
const char *fragmentShaderSource = "#version 330 core\n"
    "out vec4 FragColor;\n"
    "in vec3 ourColor;\n"
    "void main(){\n"
    "   FragColor = vec4(ourColor, 1.0f);\n"
    "}";
void framebuffer_size_callback(GLFWwindow* window, int width, int height){
    printf("window=%p\n", window);
    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(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);
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)){
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }
    int vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);
    int success;
    char infoLog[512];
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
    if (!success){
        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
    }
    int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, 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;
    }
    int 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);
    float vertices[] = {
        // positions         // colors
        -0.5f, -0.5f, 0.0f,  1.0, 0.0, 0.0, // left
         0.5f, -0.5f, 0.0f,  0.0, 1.0, 0.0, // right
         0.0f,  0.5f, 0.0f,  0.0, 0.0, 1.0, // top
    };
    unsigned int VBO, VAO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    // bind the Vertex Array Object first, then bind and set vertex buffer(s), and then configure vertex attributes(s).
    glBindVertexArray(VAO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    // position
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // position
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);
    // note that this is allowed, the call to glVertexAttribPointer registered VBO as the vertex attribute's bound vertex buffer object so afterwards we can safely unbind
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    // You can unbind the VAO afterwards so other VAO calls won't accidentally modify this VAO, but this rarely happens. Modifying other
    // VAOs requires a call to glBindVertexArray anyways so we generally don't unbind VAOs (nor VBOs) when it's not directly necessary.
    glBindVertexArray(0);
    int wireframe = 0;
    while (!glfwWindowShouldClose(window)){
        glfwPollEvents();
        if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
           glfwSetWindowShouldClose(window, true);
        if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
           wireframe = 1 - wireframe;
        glPolygonMode(GL_FRONT_AND_BACK, wireframe ? GL_LINE : GL_FILL);
        // render
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);
        // draw our first triangle
float timeValue = glfwGetTime();
float xOfs = (sin(timeValue) / 2.0f);
int vertexColorLocation = glGetUniformLocation(shaderProgram, "aOfs");
glUniform3f(vertexColorLocation, xOfs, 0.0f, 0.0f);
        glUseProgram(shaderProgram);
        glBindVertexArray(VAO); // seeing as we only have a single VAO there's no need to bind it every time, but we'll do so to keep things a bit more organized
        glDrawArrays(GL_TRIANGLES, 0, 3);
        // glBindVertexArray(0); // no need to unbind it every time
        glfwSwapBuffers(window);
    }
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glfwTerminate();
    return 0;
}