Merge pull request 'implement basic collision and interpolation' (#6) from collision into main

Reviewed-on: #6

src/corelib/world.c

@@ -110,7 +110,7 @@ static inline
 short _collision_circle_aabb(const object_t* circle, const object_t* aabb) {
 	// generate a point on the edge of the rectangle that is closest to the circle
 	const float bbminx = aabb->collider.aabb.x + aabb->sprite.x, bbmaxx = bbminx + aabb->collider.aabb.w,
-				bbminy = aabb->collider.aabb.y + aabb->sprite.x, bbmaxy = bbminy + aabb->collider.aabb.h;
+				bbminy = aabb->collider.aabb.y + aabb->sprite.y, bbmaxy = bbminy + aabb->collider.aabb.h;
 	const float cx = circle->sprite.x + circle->collider.circle.x,
 				cy = circle->sprite.y + circle->collider.circle.y;
 	const float x = fclampf(cx, bbminx, bbmaxx),
@@ -141,7 +141,13 @@ short _collision_check(const object_t* a, const object_t* b) {
 
 static inline
 short _can_collide(const object_t* object) {
-	return object->active && object->enabled && object->collider.evt_collision != NULL;
+	return object->active && object->enabled;
+}
+
+void object_broadcast_collision(object_t* this, object_t* other) {
+	if(this->collider.evt_collision != NULL) {
+		this->collider.evt_collision(this, other);
+	}
 }
 
 void update_collision() {
@@ -153,8 +159,8 @@ void update_collision() {
 			if(!_can_collide(oobject)) continue;
 
 			if(outer != inner && _collision_check(iobject, oobject)) {
-				oobject->collider.evt_collision(oobject, iobject);
+				object_broadcast_collision(oobject, iobject);
-				iobject->collider.evt_collision(iobject, oobject);
+				object_broadcast_collision(iobject, oobject);
 			}
 		}
 	}
@@ -170,35 +176,41 @@ object_t* interpolate_move(object_t* object, float target_x, float target_y, flo
 
 	// ensure this object would ever collide
 	// if it wouldn't collide anyway, just set position
-	if(_can_collide(object)) {
+	if(!_can_collide(object)) {
 		object->sprite.x = target_x;
 		object->sprite.y = target_y;
 		return NULL;
 	}
 
 	/*
-	 * 1. check collision with every other object
+	 * 1. move towards target
-	 * 2. move towards target
+	 * 2. check collision with every other object
 	 */
 	while(object->sprite.x != target_x || object->sprite.y != target_y) {
-		for(int i = 0; i < WORLD_NUM_OBJECTS; ++i) {
-			object_t* other = g_objects + i;
-			if(!_can_collide(other)) continue;
-			if(object != other && _collision_check(other, object)) {
-				other->collider.evt_collision(other, object);
-				object->collider.evt_collision(object, other);
-				return other;
-			}
-		}
-
 		// move towards target, snap to target if distance is too low
-		float distx = fabsf(object->sprite.x - target_x), disty = fabsf(object->sprite.y - target_y);
+		const float old_x = object->sprite.x, old_y = object->sprite.y;
+		const float distx = fabsf(object->sprite.x - target_x), disty = fabsf(object->sprite.y - target_y);
 		if(distx < fabsf(dx) && disty < fabsf(dy)) {
-			object->sprite.x += dx; object->sprite.y += dy;
+			object->sprite.x += dx;
+			object->sprite.y += dy;
 		} else {
 			object->sprite.x = target_x;
 			object->sprite.y = target_y;
 		}
+
+		// loop over all objects and check collision if applicable
+		for(int i = 0; i < WORLD_NUM_OBJECTS; ++i) {
+			// get pointer to other object
+			object_t* other = g_objects + i;
+			// check collision, return if found
+			if(_can_collide(other) && object != other && _collision_check(other, object)) {
+				object_broadcast_collision(other, object);
+				object_broadcast_collision(object, other);
+				object->sprite.x = old_x;
+				object->sprite.y = old_y;
+				return other;
+			}
+		}
 	}
 
 	// no collision, return nothing

src/corelib/world.h

@@ -55,6 +55,7 @@ object_t* instantiate_object(const object_t* original);
 collider_t collider_default();
 
 void object_draw_sprite(object_t* object);
+void object_broadcast_evt_collision(object_t* this, object_t* other);
 
 void update_objects();
 void draw_objects();