function platformDetect() {
	var pTop, pBottom, pLeft, pRight, cTop, cBottom, cLeft, cRight;
	if (xmov==0 && ymov==0)
		return;
	collTime=1;
	for (i=0;i<platforms.length;i++) {

		pTop = platforms[i].y;
		pBottom = platforms[i].y + platforms[i].height;
		pLeft = platforms[i].x;
		pRight = platforms[i].x +platforms[i].width;
		cTop = circle._y;
		cBottom = circle._y + circle._height;
		cLeft = circle._x;
		cRight = circle._x + circle._width;
	
	
		cTop += ymov;
		cBottom += ymov;
		cLeft += xmov;
		cRight += xmov;
		
		// check if we've collided with the platform
		if ((cBottom >= pTop) && (cTop <= pBottom) && (cRight >= pLeft) && (cLeft <+ pRight)) {
		// now find which side we hit.

			// check top
			if (cBottom-ymov<=pTop) {
				if (ymov>0) {
					var tmp = (pTop-cBottom+ymov)/ymov;
					if (tmp<=collTime) {
						collTime=tmp;
						hitClip = "squashBottom";	
					}
				}
				else
					onSurface=true;
			}
			// check bottom
			else if (cTop-ymov>=pBottom && ymov<0) {
				var tmp = (pBottom-cTop+ymov)/ymov; 
				if (tmp < collTime) {
					collTime=tmp;
					hitClip = "squashTop";
				}
			} 
			// check left of platform
			if (cRight-xmov<=pLeft && xmov>0) {
				//hit the left side of the platform
				var tmp = (pLeft - cRight + xmov)/xmov;
				if (tmp < collTime) {
					collTime = tmp;
					hitClip = "squashRight";
				}
			} 
			else if (cLeft-xmov >= pRight && xmov < 0) {
				// hit the right side of the platfrom
				var tmp = (pRight - cLeft + xmov)/xmov;
				if (tmp < collTime) {
					collTime=tmp;
					hitClip="squashLeft";
				}
			}
		}
	}
}