| Код | // determine if 2 line cross given their end-points
function LinesCross(LineAP1, LineAP2, LineBP1, LineBP2 : TPoint) : boolean;
Var
diffLA, diffLB : TPoint;
CompareA, CompareB : integer;
begin
Result := False;
diffLA := Subtract(LineAP2, LineAP1);
diffLB := Subtract(LineBP2, LineBP1);
CompareA := diffLA.X*LineAP1.Y - diffLA.Y*LineAP1.X;
CompareB := diffLB.X*LineBP1.Y - diffLB.Y*LineBP1.X;
if ( ((diffLA.X*LineBP1.Y - diffLA.Y*LineBP1.X) < CompareA) xor
((diffLA.X*LineBP2.Y - diffLA.Y*LineBP2.X) < CompareA) ) and
( ((diffLB.X*LineAP1.Y - diffLB.Y*LineAP1.X) < CompareB) xor
((diffLB.X*LineAP2.Y - diffLB.Y*LineAP2.X) < CompareB) ) then
Result := True;
end;
function LineIntersect(LineAP1, LineAP2, LineBP1, LineBP2 : TPoint) : TPointFloat;
Var
LDetLineA, LDetLineB, LDetDivInv : Real;
LDiffLA, LDiffLB : TPoint;
begin
LDetLineA := LineAP1.X*LineAP2.Y - LineAP1.Y*LineAP2.X;
LDetLineB := LineBP1.X*LineBP2.Y - LineBP1.Y*LineBP2.X;
LDiffLA := Subtract(LineAP1, LineAP2);
LDiffLB := Subtract(LineBP1, LineBP2);
LDetDivInv := 1 / ((LDiffLA.X*LDiffLB.Y) - (LDiffLA.Y*LDiffLB.X));
Result.X := ((LDetLineA*LDiffLB.X) - (LDiffLA.X*LDetLineB)) * LDetDivInv;
Result.Y := ((LDetLineA*LDiffLB.Y) - (LDiffLA.Y*LDetLineB)) * LDetDivInv;
end;
function Subtract(AVec1, AVec2 : TPoint) : TPoint;
begin
Result.X := AVec1.X - AVec2.X;
Result.Y := AVec1.Y - AVec2.Y;
end; |
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