xlib_playground

Xlib playground for experiments.
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obj.h (2216B)

      1 typedef struct Obj{
      2 	float ppx, ppy; //previous position
      3 	float px, py;   //current position
      4 	float vx, vy;   //velocity
      5 	float ax, ay;   //acceleration
      6 	float m;        //mass
      7 	float width, height;
      8 } Obj;
      9 
     10 Obj *obj_create(float px, float py,
     11 				float vx, float vy,
     12 				float ax, float ay,
     13 				float m,
     14 				float width, float height);
     15 void obj_move(Obj *obj, float px, float py); // move obj to the pos 
     16 void obj_next_tick(Obj *obj, float dt); // move obj by velocity * dt
     17 void obj_accel(Obj *obj, float ax, float ay); // accelerate obj by accel
     18 int obj_test_collision(Obj *obj1, Obj *obj2);
     19 void obj_handle_collision(Obj *obj1, Obj *obj2);
     20 
     21 Obj
     22 *obj_create(float px, float py,
     23 				float vx, float vy,
     24 				float ax, float ay,
     25 				float m,
     26 				float width, float height)
     27 {
     28 	Obj *obj;
     29 	obj = (Obj *) malloc(sizeof(Obj));
     30 	obj->ppx = obj->px = px;
     31 	obj->ppy = obj->py = py;
     32 	obj->vx = vx;
     33 	obj->vy = vy;
     34 	obj->ax = ax;
     35 	obj->ay = ay;
     36 	obj->m = m;
     37 	obj->width = width;
     38 	obj->height = height;
     39 	return obj;
     40 }
     41 
     42 void
     43 obj_move(Obj *obj, float px, float py)
     44 {
     45 	obj->ppx = obj->px = px;
     46 	obj->ppy = obj->py = py;
     47 }
     48 
     49 void
     50 obj_next_tick(Obj *obj, float dt)
     51 {
     52 	obj->ppx = obj->px;
     53 	obj->ppy = obj->py;
     54 	obj->vx += obj->ax * dt;
     55 	obj->vy += obj->ay * dt;
     56 	obj->px += obj->vx * dt;
     57 	obj->py += obj->vy * dt;
     58 }
     59 
     60 void
     61 obj_accel(Obj *obj, float ax, float ay)
     62 {
     63 	obj->vx += ax;
     64 	obj->vy += ay;
     65 }
     66 
     67 
     68 int
     69 obj_test_collision(Obj *obj1, Obj *obj2)
     70 {
     71 	return obj1->py < obj2->py + obj2->height &&
     72 		   obj2->py < obj1->py + obj1->height &&
     73 		   obj1->px < obj2->px + obj2->width &&
     74 		   obj2->px < obj1->px + obj1->width;
     75 }
     76 
     77 void
     78 obj_handle_collision(Obj *obj1, Obj *obj2)
     79 {
     80 	if(!obj_test_collision(obj1, obj2))
     81 		return;
     82 
     83 	float v1, v2;
     84 	float m1 = obj1->m;
     85 	float m2 = obj2->m;
     86 
     87 	if (obj2->ppy + obj2->height <= obj1->ppy ||
     88 			obj1->ppy + obj1->height <= obj2->ppy){
     89 		v1 = obj1->vy;
     90 		v2 = obj2->vy;
     91 		obj1->vy = 2*m2/(m1+m2)*v2 + (m1-m2)/(m1+m2)*v1;
     92 		obj2->vy = 2*m1/(m1+m2)*v1 + (m2-m1)/(m1+m2)*v2;
     93 	}else if (obj2->ppx + obj2->width <= obj1->ppx ||
     94 			obj1->ppx + obj1->width <= obj2->ppx){
     95 		v1 = obj1->vx;
     96 		v2 = obj2->vx;
     97 		obj1->vx = 2*m2/(m1+m2)*v2 + (m1-m2)/(m1+m2)*v1;
     98 		obj2->vx = 2*m1/(m1+m2)*v1 + (m2-m1)/(m1+m2)*v2;
     99 	}
    100 
    101 }