[bb] LineRectIntersection by Markus Rosse [ 1+ years ago ]

[BlitzBot]

Title : LineRectIntersection
Author : Markus Rosse
Posted : 1+ years ago

Description : This Function determine if a Line and a Rectangle intersect

Code :

Code (blitzbasic) Select Expand

Global LineRectIntersectionX#,LineRectIntersectionY# ; Important!
;----------------------------------------------------------------------------------------------------
; This Function determine if a Line and a Rectangle intersect. If there is a intersection, the
; Function returns TRUE, otherwise FALSE. The Coordinates of the first Intersection of the Line
; are returned in the global Variables LineRectIntersectionX# and LineRectIntersectionY#.
;----------------------------------------------------------------------------------------------------
Function LineRectIntersection(LineX1#,LineY1#,LineX2#,LineY2#,RectX#,RectY#,RectWidth#,RectHeight#)
Local b#,m#,x#,Intersection
If LineY1#=LineY2#
If LineX1#<LineX2#
For x#=LineX1# To LineX2#
If x#>=RectX# And x#<=RectX#+RectWidth# And LineY1#>=RectY# And LineY1#<=RectY#+RectHeight#
LineRectIntersectionX#=x#
LineRectIntersectionY#=y#
Intersection=True
End If
Next
Else
For x#=LineX1# To LineX2# Step -1
If x#>=RectX# And x#<=RectX#+RectWidth# And LineY1#>=RectY# And LineY1#<=RectY#+RectHeight#
LineRectIntersectionX#=x#
LineRectIntersectionY#=y#
Intersection=True
End If
Next
End If
ElseIf LineX1#=LineX2#
If LineY1#<LineY2#
For y#=LineY1# To LineY2#
If LineX1#>=RectX# And LineX1#<=RectX#+RectWidth# And y#>=RectY# And y#<=RectY#+RectHeight#
LineRectIntersectionX#=x#
LineRectIntersectionY#=y#
Intersection=True
End If
Next
Else
For y#=LineY1# To LineY2# Step -1
If LineX1#>=RectX# And LineX1#<=RectX#+RectWidth# And y#>=RectY# And y#<=RectY#+RectHeight#
LineRectIntersectionX#=x#
LineRectIntersectionY#=y#
Intersection=True
End If
Next
End If
Else
m#=(LineY1#-LineY2#)/(LineX1#-LineX2#)
b#=LineY1#-(m#*LineX1)
If LineX1#<LineX2#
For x#=LineX1# To LineX2#
y#=(m#*x#)+b#
If x#>=RectX# And x#<=RectX#+RectWidth# And y#>=RectY# And y#<=RectY#+RectHeight#
LineRectIntersectionX#=x#
LineRectIntersectionY#=y#
Intersection=True
End If
Next
Else
For x#=LineX1# To LineX2# Step -1
y#=(m#*x#)+b#
If x#>=RectX# And x#<=RectX#+RectWidth# And y#>=RectY# And y#<=RectY#+RectHeight#
LineRectIntersectionX#=x#
LineRectIntersectionY#=y#
Intersection=True
End If
Next
End If
If Not Intersection
If LineY1#<LineY2#
For y#=LineY1# To LineY2#
x#=(y#-b#)/m#
If x#>=RectX# And x#<=RectX#+RectWidth# And y#>=RectY# And y#<=RectY#+RectHeight#
LineRectIntersectionX#=x#
LineRectIntersectionY#=y#
Intersection=True
End If
Next
Else
For y#=LineY1# To LineY2# Step -1
x#=(y#-b#)/m#
If x#>=RectX# And x#<=RectX#+RectWidth# And y#>=RectY# And y#<=RectY#+RectHeight#
LineRectIntersectionX#=x#
LineRectIntersectionY#=y#
Intersection=True
End If
Next
End If
End If
End If
Return Intersection
End Function

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