Fast collision mapping?

Ok, line intersect then

code here

Function Ray2dintersect(x1,y1,x2,y2,x3,y3,x4,y4)
  d# = (y4-y3)*(x2-x1) - (x4-x3)*(y2-y1)
  If d = 0 Then Return 0
  ua# =((x4-x3)*(y1-y3) - (y4-y3)*(x1-x3)) / d#
  ub# =((x2-x1)*(y1-y3) - (y2-y1)*(x1-x3)) / d#
  If (ua# >= 0.0) And (ub# >= 0.0) And (ub# <= 1.0)
	intersectedx#=x1+ua*(x2-x1)
	intersectedy#=y1+ua*(y2-y1)
	Return 1
  EndIf
Return 0
End Function