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Add support for polygon selection shapes.

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This commit is contained in:
Paul Chote
2020-02-29 11:03:20 +00:00
committed by atlimit8
parent 4ba50a4379
commit 88cdad4189
11 changed files with 162 additions and 35 deletions
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12
OpenRA.Game/Exts.cs
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@@ -80,7 +80,7 @@ namespace OpenRA
static int WindingDirectionTest(int2 v0, int2 v1, int2 p)
{
return (v1.X - v0.X) * (p.Y - v0.Y) - (p.X - v0.X) * (v1.Y - v0.Y);
return Math.Sign((v1.X - v0.X) * (p.Y - v0.Y) - (p.X - v0.X) * (v1.Y - v0.Y));
}
public static bool PolygonContains(this int2[] polygon, int2 p)
@@ -101,6 +101,16 @@ namespace OpenRA
return windingNumber != 0;
}
public static bool LinesIntersect(int2 a, int2 b, int2 c, int2 d)
{
// If line segments AB and CD intersect:
// - the triangles ACD and BCD must have opposite sense (clockwise or anticlockwise)
// - the triangles CAB and DAB must have opposite sense
// Segments intersect if the orientation (clockwise or anticlockwise) of the two points in each line segment are opposite with respect to the other
// Assumes that lines are not colinear
return WindingDirectionTest(c, d, a) != WindingDirectionTest(c, d, b) && WindingDirectionTest(a, b, c) != WindingDirectionTest(a, b, d);
}
public static bool HasModifier(this Modifiers k, Modifiers mod)
{
// PERF: Enum.HasFlag is slower and requires allocations.