Simple screen buffer with OpenGL2 and GLFW3

main.c

// simple screen buffer with OpenGL 2 (and GLFW3)
// build with:
// Linux: gcc main.c -lglfw -lGL
// macOS: gcc main.c -lglfw -framework OpenGL

#include <GLFW/glfw3.h>

static const int WIN_WIDTH = 160;
static const int WIN_HEIGHT = 144;

int main(int argc, char **argv) {
    // GLFW setup (creating window + OpenGL context)
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);

    GLFWwindow* window;

    if (!glfwInit()) {
        return -1;
    }

    window = glfwCreateWindow(WIN_WIDTH * 2, WIN_HEIGHT * 2, "test",
                              NULL, NULL);
    if (!window) {
        glfwTerminate();
        return -1;
    }
    glfwSetWindowSizeLimits(window, WIN_WIDTH, WIN_HEIGHT,
                            GLFW_DONT_CARE, GLFW_DONT_CARE);

    glfwMakeContextCurrent(window);
    glfwSwapInterval(1);

    // 
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    float screen_buffer[WIN_HEIGHT][WIN_WIDTH][3];
    GLuint texture;

    // zero-ing the screen_buffer + putting random values in it
    for (int x=0; x<WIN_WIDTH; x++) {
        for (int y=0; y<WIN_HEIGHT; y++) {
            screen_buffer[y][x][0] = 0;
            screen_buffer[y][x][1] = 0;
            screen_buffer[y][x][2] = 0;
        }
    }

    screen_buffer[80][80][0] = 0;
    screen_buffer[80][80][1] = 1;
    screen_buffer[80][80][2] = 0;

    screen_buffer[81][80][0] = 1;
    screen_buffer[81][80][1] = 0;
    screen_buffer[81][80][2] = 0;

    screen_buffer[83][85][0] = 0;
    screen_buffer[83][85][1] = 0;
    screen_buffer[83][85][2] = 1;

    // creating the OpenGL texture
    glGenTextures(1, &texture); // create texture
    glBindTexture(GL_TEXTURE_2D, texture); // specify that the texture is 2D
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glEnable(GL_TEXTURE_2D);

    // copying the contents of screen_buffer to the OpenGL texture
    // call that every time you want to update the texture with new buffer
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, WIN_WIDTH, WIN_HEIGHT, 0,
                 GL_RGB, GL_FLOAT, screen_buffer);

    while (!glfwWindowShouldClose(window)) {
        glClear(GL_COLOR_BUFFER_BIT);

        // draw the textured quad
        glBegin(GL_QUADS);
        glTexCoord2f(0, 0); glVertex2f(-1, 1);
        glTexCoord2f(0, 1); glVertex2f(-1, -1);
        glTexCoord2f(1, 1); glVertex2f(1, -1);
        glTexCoord2f(1, 0); glVertex2f(1, 1);
        glEnd();

        glfwSwapBuffers(window);

        glfwPollEvents();
    }

    return 0;
}