tex4glad.cpp

#include <unistd.h>
#include <math.h>
#include <iostream>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
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"
    "layout (location = 2) in vec2 aTexCoord;\n"
    "out vec3 ourColor;\n"
    "out vec2 TexCoord;\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"
    "   TexCoord = aTexCoord;\n"
    "}";
const char *fragmentShaderSource = "#version 330 core\n"
    "out vec4 FragColor;\n"
    "in vec3 ourColor;\n"
    "in vec2 TexCoord;\n"
    "uniform sampler2D ourTexture;\n"
    "void main(){\n"
//    "   FragColor = vec4(ourColor, 1.0f);\n"
    "   FragColor = texture(ourTexture, TexCoord);\n"
//    "   FragColor = texture(ourTexture, TexCoord) * vec4(ourColor, 1.0);\n"
    "}";
static void *g_p = 0;
void framebuffer_size_callback(GLFWwindow* window, int width, int height){
//    printf("window=%p\n", window);
    g_p = 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           // texture coords
     0.5f,  0.5f, 0.0f,   1.0f, 0.0f, 0.0f,   1.0f, 1.0f,   // top right
     0.5f, -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 triangle
        1, 2, 3  // second triangle
    };
    unsigned int VBO, VAO, EBO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);
    // 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);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    // positions
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // colors
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);
    // tex coords
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
    glEnableVertexAttribArray(2);
    // 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);
    unsigned int texture;
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
// set the texture wrapping/filtering options (on the currently bound texture object)
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);
// load and generate the texture
int width, height, nrChannels;
unsigned char *data = 0;
#if 0
data = stbi_load("textures/wall.jpg", &width, &height, &nrChannels, 0);
#else
width = SCR_WIDTH;
height = SCR_HEIGHT;
nrChannels = 4;
data = (unsigned char *)calloc(width * height, nrChannels);
#endif
if (data)
{
	printf("channels=%d\n", (int)nrChannels);
//    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;
}

#if 1
	char col = 0;
	for (int j = 0; j < height; j++) {
		if (!(j % 10))
			col = 255 - col;
		for (int i = 0; i < width; i++) {
			if (!(i % 10))
				col = 255 - col;
			data[j * width * nrChannels + i * nrChannels + 0] = col;
			data[j * width * nrChannels + i * nrChannels + 1] = 0;
			data[j * width * nrChannels + i * nrChannels + 2] = 0;
			if ((i < width / 3) || (i > 2 * width / 3))
				data[j * width * nrChannels + i * nrChannels + 3] = 255;
		}
	}
#endif
    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 quad
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

float timeValue = glfwGetTime();
float xOfs = (sin(timeValue) / 1.9f);
int vertexColorLocation = glGetUniformLocation(shaderProgram, "aOfs");
glUniform3f(vertexColorLocation, xOfs, 0.0f, 0.0f);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);

        glBindTexture(GL_TEXTURE_2D, texture);
        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
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
        // glBindVertexArray(0); // no need to unbind it every time
        glfwSwapBuffers(window);
        usleep(50000);
    }
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteBuffers(1, &EBO);
    glfwTerminate();
    if (data) {
stbi_image_free(data);
    }
    return 0;
}