Keskustelu: Koodit: C: Pyörivä neliö

#include <math.h>
#include <SDL.h>
#include <SDL_gfxPrimitives.h>


#define WINDOW_WIDTH 400
#define WINDOW_HEIGHT 300

int main()
{
  SDL_Surface *screen;
  SDL_Event event;
  float p1x= 0, p1y = 0, p2x = 0, p2y = 0, p3x = 0, p3y = 0, p4x = 0, p4y = 0, k=0;
  int size = 100;

  /* Initialize SDL */
  if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
    fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
    exit(1);
  }
  atexit(SDL_Quit);

  /* Set up videomode */
  screen = SDL_SetVideoMode (WINDOW_WIDTH, WINDOW_HEIGHT, 16, SDL_SWSURFACE);

  /* Main loop */
  while( SDL_PollEvent(&event) >= 0 ) {
    p1x = WINDOW_WIDTH / 2 + sin(k) * size;
    p2x = WINDOW_WIDTH / 2 + sin(k + (3.14/2)) * size;
    p3x = WINDOW_WIDTH / 2 + sin(k + 3.14) * size;
    p4x = WINDOW_WIDTH / 2 + sin(k + 3.14 + (3.14/2)) * size;
    p1y = WINDOW_HEIGHT / 2 + cos(k) * size;
    p2y = WINDOW_HEIGHT / 2 + cos(k + (3.14/2)) * size;
    p3y = WINDOW_HEIGHT / 2 + cos(k + 3.14) * size;
    p4y = WINDOW_HEIGHT / 2 + cos(k + 3.14 + (3.14/2)) * size;
    k += 0.1;

    /* Draw rectangle */
    lineRGBA(screen, p1x, p1y, p2x, p2y, 255, 255, 0, 255);
    lineRGBA(screen, p2x, p2y, p3x, p3y, 255, 255, 0, 255);
    lineRGBA(screen, p3x, p3y, p4x, p4y, 255, 255, 0, 255);
    lineRGBA(screen, p4x, p4y, p1x, p1y, 255, 255, 0, 255);

    /* Update screen */
    SDL_Flip(screen);

    /* Clear screen */
    SDL_FillRect(screen, NULL, SDL_MapRGB(screen->format, 0, 0, 0));

    /* Handle keys... */
    if (event.type==SDL_QUIT) {
      printf("Quitting.\n");
      exit(0);
    } else if (event.type==SDL_KEYDOWN && event.key.keysym.sym==SDLK_LEFT) {
      size -= 3;
    } else if (event.type==SDL_KEYDOWN && event.key.keysym.sym==SDLK_RIGHT) {
      size += 3;
    }
  }
  return(0);
}