Столкновение объектов

[Cuba25]

Здравтсвуйте!!!
Помогите, пожалуйста, разобраться со следующим кодом:

function ProjCircle_Concave(x,y,oH,oV,obj,t) {
	//if we're colliding diagonally:										
	//	-if obj is in the diagonal pointed to by the slope normal: we can't collide, do nothing	
	//  -else, collide vs. the appropriate vertex									
	//if obj is horiz OR very neighb in direction of slope: collide vs vert				
	//if obj is horiz or vert neigh against direction of slope: collide vs. face				
	var signx = t.signx;
	var signy = t.signy;
	if(oH == 0) {
		if(oV == 0) {
			//colliding with current tile				
				var ox = (t.pos.x + (signx*t.xw)) - obj.pos.x;
				var oy = (t.pos.y + (signy*t.yw)) - obj.pos.y;
				var twid = t.xw*2;
				var trad = Math.sqrt(twid*twid + 0);
				var len = Math.sqrt(ox*ox + oy*oy);
				var pen = (len + obj.r) - trad;
				if(0 < pen) {
					//find the smallest axial projection vector		
					if(x < y) {					
						//penetration in x is smaller			
						lenP = x;
						y = 0;
						//get sign for projection along x-axis			
						if((obj.pos.x - t.pos.x) < 0) {
							x *= -1;
						}
					}
					else {		
						//penetration in y is smaller		
						lenP = y;
						x = 0;
						//get sign for projection along y-axis		
						if((obj.pos.y - t.pos.y)< 0) {
							y *= -1;
						}			
					}
					if(lenP < pen) {
						obj.ReportCollisionVsWorld(x,y,x/lenP, y/lenP, t);
						return COL_AXIS;
					}
					else {
						ox /= len;
						oy /= len;
						obj.ReportCollisionVsWorld(ox*pen, oy*pen, ox, oy, t);
						return COL_OTHER;
					}
				}
				else {
					return COL_NONE;
				}

		}
		else {
			//colliding vertically			
			if((signy*oV) < 0) {			
				//colliding with face/edge	
				obj.ReportCollisionVsWorld(0,y*oV, 0, oV, t);
				return COL_AXIS;
			}
			else {
				var vx = t.pos.x - (signx*t.xw);
				var vy = t.pos.y + (oV*t.yw);
				var dx = obj.pos.x - vx;		
				var dy = obj.pos.y - vy;
				var len = Math.sqrt(dx*dx + dy*dy);
				var pen = obj.r - len;
				if(0 < pen) {
					//vertex is in the circle; project outward		
					if(len == 0) {
						//project out vertically		
						dx = 0;
						dy = oV;
					}
					else {
						dx /= len;
						dy /= len;
					}
					obj.ReportCollisionVsWorld(dx*pen, dy*pen, dx, dy, t);
					return COL_OTHER;
				}
			}
		}		
	}
	else if(oV == 0) {
		//colliding horizontally				
		if((signx*oH) < 0) {
			//colliding with face/edge		
			obj.ReportCollisionVsWorld(x*oH, 0, oH, 0, t);
			return COL_AXIS;
		}
		else {
				//we could only be colliding vs the horizontal tip		
				//get diag vertex position
				var vx = t.pos.x + (oH*t.xw);
				var vy = t.pos.y - (signy*t.yw);
				var dx = obj.pos.x - vx;//calc vert->circle vector		
				var dy = obj.pos.y - vy;
				var len = Math.sqrt(dx*dx + dy*dy);
				var pen = obj.r - len;
				if(0 < pen) {
					//vertex is in the circle; project outward			
					if(len == 0) {
						//project out horizontally		
						dx = oH;
						dy = 0;
					}
					else {
						dx /= len;
						dy /= len;
					}
					obj.ReportCollisionVsWorld(dx*pen, dy*pen, dx, dy, t);
					return COL_OTHER;
				}	
		}
	}
	else {
		//colliding diagonally		
		if( 0 < ((signx*oH) + (signy*oV)) ) {
			//the dotprod of slope normal and cell offset is strictly positive,			
			//therefore obj is in the diagonal neighb pointed at by the normal, and
			//it cannot possibly reach/touch/penetrate the slope
			return COL_NONE;
		} 
		else {
			//collide vs. vertex		
			//get diag vertex position	
			var vx = t.pos.x + (oH*t.xw);
			var vy = t.pos.y + (oV*t.yw);
			var dx = obj.pos.x - vx;//calc vert->circle vector		
			var dy = obj.pos.y - vy;
			var len = Math.sqrt(dx*dx + dy*dy);
			var pen = obj.r - len;
			if(0 < pen) {
				//vertex is in the circle; project outward			
				if(len == 0) {
					//project out by 45deg		
					dx = oH / Math.SQRT2;
					dy = oV / Math.SQRT2;
				}
				else {
					dx /= len;
					dy /= len;
				}
				obj.ReportCollisionVsWorld(dx*pen, dy*pen, dx, dy, t);
				return COL_OTHER;
			}
		}
	}
	return COL_NONE;
}