feat: Circle & Shape Projections

Engine.Physics2D/Primitives/Circle.cs

@@ -13,6 +13,12 @@ public record Circle(Vector2D Center, float Radius)
 
     public static Circle Displace(Circle circle, Vector2D displaceVector) => new(circle.Center + displaceVector, circle.Radius);
 
+    public static Projection Project(Circle circle, Vector2D projectionVector)
+    {
+        float projectedCenter = circle.Center.Dot(projectionVector);
+        return new(projectedCenter - circle.Radius, projectedCenter + circle.Radius);
+    }
+
     public static Circle TransformCircle(ITransform transform, Circle circle)
         => new(transform.TransformVector2D(circle.Center), circle.Radius * transform.Scale.Magnitude);
 
@@ -27,6 +33,8 @@ public static class CircleExtensions
 
     public static Circle Displace(this Circle circle, Vector2D displaceVector) => Circle.Displace(circle, displaceVector);
 
+    public static Projection ToProjection(this Circle circle, Vector2D projectionVector) => Circle.Project(circle, projectionVector);
+
     public static Circle TransformCircle(this ITransform transform, Circle circle) => Circle.TransformCircle(transform, circle);
 
     public static bool ApproximatelyEquals(this Circle left, Circle right) => Circle.ApproximatelyEquals(left, right);

Engine.Physics2D/Primitives/Shape.cs

@@ -53,6 +53,30 @@ public record Shape(IList<Vector2D> Vertices) : IEnumerable<Vector2D>
         return lines;
     }
 
+    public static void Project(Shape shape, Vector2D projectionVector, IList<float> list)
+    {
+        list.Clear();
+
+        int count = shape.Vertices.Count;
+        for (int i = 0; i < count; i++)
+            list.Add(projectionVector.Dot(shape[i]));
+    }
+
+    public static Projection Project(Shape shape, Vector2D projectionVector)
+    {
+        float min = float.MaxValue;
+        float max = float.MinValue;
+
+        foreach (var vertex in shape)
+        {
+            float projectedLength = projectionVector.Dot(vertex);
+            min = Math.Min(projectedLength, min);
+            max = Math.Max(projectedLength, max);
+        }
+
+        return new(min, max);
+    }
+
     public static Shape TransformShape(Shape shape, ITransform transform)
     {
         List<Vector2D> vertices = new(shape.Vertices.Count);
@@ -96,6 +120,9 @@ public static class ShapeExtensions
     public static void ToLines(this Shape shape, IList<Line> lines) => Shape.GetLines(shape, lines);
     public static List<Line> ToLines(this Shape shape) => Shape.GetLines(shape);
 
+    public static void ToProjection(this Shape shape, Vector2D projectionVector, IList<float> list) => Shape.Project(shape, projectionVector, list);
+    public static Projection ToProjection(this Shape shape, Vector2D projectionVector) => Shape.Project(shape, projectionVector);
+
     public static Shape TransformShape(this ITransform transform, Shape shape) => Shape.TransformShape(shape, transform);
     public static void TransformShape(this ITransform transform, Shape from, ref Shape to) => Shape.TransformShape(from, transform, ref to);