#include <stdio.h>
#include <windows.h>
#include <gl/gl.h>

#define GRID_SIZE  10
#define GRID_STEP  20.0f

int main() {
    HDC hDC = GetDC(CreateWindow("static", "Grid Test", WS_POPUP | WS_VISIBLE, 0, 0, 800, 600, 0, 0, 0, 0));
    PIXELFORMATDESCRIPTOR pfd = { 0 };
    pfd.nSize        = sizeof(pfd);
    pfd.nVersion     = 1;
    pfd.dwFlags      = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
    pfd.cColorBits   = 32;

    SetPixelFormat(hDC, ChoosePixelFormat(hDC, &pfd), &pfd);
    wglMakeCurrent(hDC, wglCreateContext(hDC));

    while (!GetAsyncKeyState(VK_ESCAPE)) {
        glClear(GL_COLOR_BUFFER_BIT);
        
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glOrtho(-400, 400, -300, 300, 0, 1);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();

        glColor3f(1, 0, 0);
        glBegin(GL_LINES);
        for (int i = -GRID_SIZE; i <= GRID_SIZE; i++) {
            glVertex2f(-GRID_SIZE * GRID_STEP, i * GRID_STEP);
            glVertex2f(+GRID_SIZE * GRID_STEP, i * GRID_STEP);
            glVertex2f(i * GRID_STEP, -GRID_SIZE * GRID_STEP);
            glVertex2f(i * GRID_STEP, +GRID_SIZE * GRID_STEP);
        }
        glEnd();

        SwapBuffers(hDC);
    }
    return 0;
}