Chipmunk Physics

Code: Select all

#include <stdio.h>
#include <allegro5/allegro.h>
#include <chipmunk/chipmunk.h>

const float FPS = 60.0;
const int SCREEN_W = 640;
const int SCREEN_H = 480;
const int BOUNCER_SIZE = 32;
int keys[ALLEGRO_KEY_MAX];
cpVect mouse;
cpBody *blocks[32];
cpSpace *space;
int n_blocks;

void add_block()
{
  cpFloat radius = 5;
  cpFloat mass = 1;
  cpFloat moment = cpMomentForCircle(mass, 0, radius, cpvzero);

  cpBody *newBody = cpSpaceAddBody(space, cpBodyNew(mass, moment));
  cpBodySetPos(newBody, cpv(mouse.x, mouse.y));

  cpShape *newShape = cpSpaceAddShape(space, cpCircleShapeNew(newBody,
                                                              radius,
                                                              cpvzero));

  cpShapeSetFriction(newShape, 1);

  blocks[n_blocks++] = newBody;
}

int main(int argc, char **argv)
{
  mouse = cpv(0, 0);
  cpVect gravity = cpv(0, 100);

  space = cpSpaceNew();
  cpSpaceSetGravity(space, gravity);

  cpShape *ground = cpSegmentShapeNew(space->staticBody, cpv(0, 300),
                                      cpv(300, 300), 0);
  cpShapeSetFriction(ground, 1);
  cpSpaceAddShape(space, ground);

  n_blocks = 0;

  cpFloat timeStep = 1.0 / FPS;

  ALLEGRO_DISPLAY *display = NULL;
  ALLEGRO_EVENT_QUEUE *event_queue = NULL;
  ALLEGRO_TIMER *timer = NULL;
  ALLEGRO_BITMAP *bouncer = NULL;
  bool redraw = true;
  bool doexit = false;

  if (!al_init()) {
    fprintf(stderr, "Failed to initialize allegro!\n");
    return -1;
  }

  if (!al_install_keyboard()) {
    fprintf(stderr, "Failed to initialize the keyboard!\n");
    return -1;
  }

  if (!al_install_mouse()) {
    fprintf(stderr, "Failed to initialize the mouse!\n");
    return -1;
  }

  timer = al_create_timer(1.0 / FPS);
  if (!timer) {
    fprintf(stderr, "Failed to create timer!\n");
    return -1;
  }

  display = al_create_display(SCREEN_W, SCREEN_H);
  if (!display) {
    fprintf(stderr, "Failed to create display!\n");
    al_destroy_timer(timer);
    return -1;
  }

  bouncer = al_create_bitmap(BOUNCER_SIZE, BOUNCER_SIZE);
  if (!bouncer) {
    fprintf(stderr, "Failed to create bouncer bitmap!\n");
    al_destroy_display(display);
    al_destroy_timer(timer);
    return -1;
  }

  al_set_target_bitmap(bouncer);
  al_clear_to_color(al_map_rgb(255, 0, 255));
  al_set_target_bitmap(al_get_backbuffer(display));

  event_queue = al_create_event_queue();
  if (!event_queue) {
    fprintf(stderr, "Failed to create event_queue!\n");
    al_destroy_bitmap(bouncer);
    al_destroy_display(display);
    al_destroy_timer(timer);
    return -1;
  }

  al_register_event_source(event_queue, al_get_display_event_source(display));
  al_register_event_source(event_queue, al_get_timer_event_source(timer));
  al_register_event_source(event_queue, al_get_mouse_event_source());
  al_register_event_source(event_queue, al_get_keyboard_event_source());
  al_clear_to_color(al_map_rgb(0,0,0));
  al_flip_display();
  al_start_timer(timer);

  while (!doexit)
  {
    cpSpaceStep(space, timeStep);
    //cpVect pos = cpBodyGetPos(ballBody);

    ALLEGRO_EVENT ev;
    al_wait_for_event(event_queue, &ev);

    if (ev.type == ALLEGRO_EVENT_TIMER) {
      if (keys[ALLEGRO_KEY_LEFT]) {
        //pos.x -= 2;
        //cpBodySetPos(ballBody, pos);
      }

      if (keys[ALLEGRO_KEY_RIGHT]) {
        //pos.x += 2;
        //cpBodySetPos(ballBody, pos);
      }

      redraw = true;
    } else if (ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE) {
      break;
    } else if (ev.type == ALLEGRO_EVENT_KEY_DOWN) {
      keys[ev.keyboard.keycode] = true;
    } else if (ev.type == ALLEGRO_EVENT_KEY_UP) {
      keys[ev.keyboard.keycode] = false;
    } else if (ev.type == ALLEGRO_EVENT_MOUSE_AXES ||
               ev.type == ALLEGRO_EVENT_MOUSE_ENTER_DISPLAY) {
      mouse.x = ev.mouse.x;
      mouse.y = ev.mouse.y;
    } else if (ev.type == ALLEGRO_EVENT_MOUSE_BUTTON_UP) {
      add_block();
    }

    if (redraw && al_is_event_queue_empty(event_queue)) {
      redraw = false;
      al_clear_to_color(al_map_rgb(0, 0, 0));

      int i;
      for (i = 0; i < n_blocks; i++) {
        cpVect pos = cpBodyGetPos(blocks[i]);
        al_draw_bitmap(bouncer, pos.x, pos.y, 0);
      }

      al_flip_display();
    }
  }

  al_destroy_bitmap(bouncer);
  al_destroy_timer(timer);
  al_destroy_display(display);
  al_destroy_event_queue(event_queue);

  cpShapeFree(ground);
  cpSpaceFree(space);

  return 0;
}

Code: Select all

void add_block()
{
  cpFloat radius = 5;
  cpFloat mass = 1;
  cpFloat moment = cpMomentForBox(mass, 32, 32);

  cpBody *newBody = cpSpaceAddBody(space, cpBodyNew(mass, moment));
  cpBodySetPos(newBody, cpv(mouse.x, mouse.y));

  cpShape *newShape = cpSpaceAddShape(space, cpBoxShapeNew(newBody,
                                                           32, 32));

  cpShapeSetFriction(newShape, 1);

  blocks[n_blocks++] = newBody;
}