Circle-rect intersection

BossMod/Util/Intersect.cs

@@ -155,4 +155,19 @@ public static bool CircleCone(WDir circleOffset, float circleRadius, float coneR
         return (circleOffset - corner).LengthSq() <= rsq;
     }
     public static bool CircleCone(WPos circleCenter, float circleRadius, WPos coneCenter, float coneRadius, WDir coneDir, Angle halfAngle) => CircleCone(circleCenter - coneCenter, circleRadius, coneRadius, coneDir, halfAngle);
+
+    public static bool CircleAARect(WDir circleOffset, float circleRadius, float halfExtentX, float halfExtentZ)
+    {
+        circleOffset = circleOffset.Abs(); // symmetrical along X/Z, consider only positive quadrant
+        var cornerOffset = circleOffset - new WDir(halfExtentX, halfExtentZ); // relative to corner
+        if (cornerOffset.X > circleRadius || cornerOffset.Z > circleRadius)
+            return false; // circle is too far from one of the edges, so can't intersect
+        if (cornerOffset.X <= 0 || cornerOffset.Z <= 0)
+            return true; // circle center is inside/on the edge, or close enough to one of the edges to intersect
+        return cornerOffset.LengthSq() <= circleRadius * circleRadius; // check whether circle touches the corner
+    }
+    public static bool CircleAARect(WPos circleCenter, float circleRadius, WPos rectCenter, float halfExtentX, float halfExtentZ) => CircleAARect(circleCenter - rectCenter, circleRadius, halfExtentX, halfExtentZ);
+
+    public static bool CircleRect(WDir circleOffset, float circleRadius, WDir rectZDir, float halfExtentX, float halfExtentZ) => CircleAARect(circleOffset.Rotate(rectZDir.MirrorX()), circleRadius, halfExtentX, halfExtentZ);
+    public static bool CircleRect(WPos circleCenter, float circleRadius, WPos rectCenter, WDir rectZDir, float halfExtentX, float halfExtentZ) => CircleRect(circleCenter - rectCenter, circleRadius, rectZDir, halfExtentX, halfExtentZ);
 }

BossMod/Util/WPosDir.cs

@@ -19,6 +19,8 @@ public WDir(Vector2 v) : this(v.X, v.Y) { }
     public readonly WDir Sign() => new(Math.Sign(X), Math.Sign(Z));
     public readonly WDir OrthoL() => new(Z, -X); // CCW, same length
     public readonly WDir OrthoR() => new(-Z, X); // CW, same length
+    public readonly WDir MirrorX() => new(-X, Z);
+    public readonly WDir MirrorZ() => new(X, -Z);
     public static float Dot(WDir a, WDir b) => a.X * b.X + a.Z * b.Z;
     public readonly float Dot(WDir a) => X * a.X + Z * a.Z;
     public static float Cross(WDir a, WDir b) => a.X * b.Z - a.Z * b.X;

TODO

@@ -1,5 +1,4 @@
 immediate plans
-- circle vs rect/cone intersection
 - proper circle bounds -> revise everything in fru
 - ai refactoring
 -- high-level ai modules

UIDev/IntersectionTest.cs

@@ -8,9 +8,10 @@ class IntersectionTest : TestWindow
     private float _cirleOffset = 5.5f;
     private float _circleDir = 0;
     private float _circleRadius = 0.5f;
-    private float _coneRadius = 5;
-    private float _coneHalfAngleDeg = 30;
-    private float _coneDirDeg = 90;
+    private float _shapeExtentPrimary = 5; // z/r
+    private float _shapeExtentSecondary = 30; // x/phi (deg)
+    private float _shapeDirDeg = 90;
+    private bool _shapeIsRect;
     private readonly MiniArena _arena = new(new(), default, new ArenaBoundsSquare(10));
 
     public IntersectionTest() : base("Intersection test", new(400, 400), ImGuiWindowFlags.NoScrollbar | ImGuiWindowFlags.NoScrollWithMouse)
@@ -22,15 +23,30 @@ public override void Draw()
         ImGui.DragFloat("Circle offset", ref _cirleOffset, 0.1f, 0, 10);
         ImGui.DragFloat("Circle dir", ref _circleDir, 1, -180, 180);
         ImGui.DragFloat("Circle radius", ref _circleRadius, 0.1f, 0.1f, 5);
-        ImGui.DragFloat("Cone radius", ref _coneRadius, 0.1f, 0.1f, 10);
-        ImGui.DragFloat("Cone half-angle", ref _coneHalfAngleDeg, 1, 0, 180);
-        ImGui.DragFloat("Cone dir", ref _coneDirDeg, 1, -180, 180);
+        ImGui.Checkbox("Intersect with rect", ref _shapeIsRect);
+        if (_shapeIsRect)
+        {
+            ImGui.DragFloat("Rect half-Z", ref _shapeExtentPrimary, 0.1f, 0.1f, 10);
+            ImGui.DragFloat("Rect half-X", ref _shapeExtentSecondary, 0.1f, 0.1f, 30);
+            ImGui.DragFloat("Rect dir", ref _shapeDirDeg, 1, -180, 180);
+        }
+        else
+        {
+            ImGui.DragFloat("Cone radius", ref _shapeExtentPrimary, 0.1f, 0.1f, 10);
+            ImGui.DragFloat("Cone half-angle", ref _shapeExtentSecondary, 1, 0, 180);
+            ImGui.DragFloat("Cone dir", ref _shapeDirDeg, 1, -180, 180);
+        }
         var circleCenter = _cirleOffset * _circleDir.Degrees().ToDirection();
-        var intersect = Intersect.CircleCone(circleCenter, _circleRadius, _coneRadius, _coneDirDeg.Degrees().ToDirection(), _coneHalfAngleDeg.Degrees());
+        var intersect = _shapeIsRect
+            ? Intersect.CircleRect(circleCenter, _circleRadius, _shapeDirDeg.Degrees().ToDirection(), _shapeExtentSecondary, _shapeExtentPrimary)
+            : Intersect.CircleCone(circleCenter, _circleRadius, _shapeExtentPrimary, _shapeDirDeg.Degrees().ToDirection(), _shapeExtentSecondary.Degrees());
         ImGui.TextUnformatted($"Intersect: {intersect}");
 
         _arena.Begin(default);
-        _arena.AddCone(default, _coneRadius, _coneDirDeg.Degrees(), _coneHalfAngleDeg.Degrees(), ArenaColor.Safe);
+        if (_shapeIsRect)
+            _arena.AddRect(default, _shapeDirDeg.Degrees().ToDirection(), _shapeExtentPrimary, _shapeExtentPrimary, _shapeExtentSecondary, ArenaColor.Safe);
+        else
+            _arena.AddCone(default, _shapeExtentPrimary, _shapeDirDeg.Degrees(), _shapeExtentSecondary.Degrees(), ArenaColor.Safe);
         _arena.AddCircle(circleCenter.ToWPos(), _circleRadius, ArenaColor.Danger);
         _arena.End();
     }