Merge pull request #17 from spacenation/rounded-star-radius-fixes

Rounded star radius fixes

Author: ay42

Sources/Shapes/CGPoint+Extensions.swift

@@ -29,20 +29,19 @@ public extension CGPoint {
 }
 
 public extension CGPoint {
-    static func intersection(start1: CGPoint, end1: CGPoint, start2: CGPoint, end2: CGPoint) -> CGPoint {
-        let x1 = start1.x
-        let y1 = start1.y
-        let x2 = end1.x
-        let y2 = end1.y
-        let x3 = start2.x
-        let y3 = start2.y
-        let x4 = end2.x
-        let y4 = end2.y
-        
-        let intersectionX: CGFloat = ((x1*y2-y1*x2)*(x3-x4) - (x1-x2)*(x3*y4-y3*x4)) / ((x1-x2)*(y3-y4) - (y1-y2)*(x3-x4))
-        let intersectionY: CGFloat = ((x1*y2-y1*x2)*(y3-y4) - (y1-y2)*(x3*y4-y3*x4)) / ((x1-x2)*(y3-y4) - (y1-y2)*(x3-x4))
-        
-        return CGPoint(x: intersectionX, y: intersectionY)
+    static func intersection(start1: CGPoint, end1: CGPoint, start2: CGPoint, end2: CGPoint) -> CGPoint? {
+        let denominator = (end1.x - start1.x) * (end2.y - start2.y) - (end1.y - start1.y) * (end2.x - start2.x)
+        if denominator == 0 {
+            // Lines are parallel or coincident
+            return nil
+        }
+
+        let ua = ((end2.x - start2.x) * (start1.y - start2.y) - (end2.y - start2.y) * (start1.x - start2.x)) / denominator
+
+        let x = start1.x + ua * (end1.x - start1.x)
+        let y = start1.y + ua * (end1.y - start1.y)
+
+        return CGPoint(x: x, y: y)
     }
 }
 

Sources/Shapes/Path+Extensions.swift

@@ -1,7 +1,18 @@
 import SwiftUI
 
 public extension Path {
-    mutating func addCircularCornerRadiusArc(from point: CGPoint, via viaPoint: CGPoint, to nextPoint: CGPoint, radius: CGFloat, clockwise: Bool) {
+    mutating func addCircularCornerRadiusArc(from point: CGPoint, via viaPoint: CGPoint, to nextPoint: CGPoint, radius: CGFloat) {
+        // Calculate the cross product to determine clockwise direction
+        let v1 = CGVector(dx: viaPoint.x - point.x, dy: viaPoint.y - point.y)
+        let v2 = CGVector(dx: nextPoint.x - viaPoint.x, dy: nextPoint.y - viaPoint.y)
+        
+        let crossProduct = v1.dx * v2.dy - v1.dy * v2.dx
+        
+        // Determine if the arc should be clockwise based on the cross product
+        let isClockwise = crossProduct < 0
+        
+        let radius = isClockwise ? -radius : radius
+        
         let lineAngle = atan2(viaPoint.y - point.y, viaPoint.x - point.x)
         let nextLineAngle = atan2(nextPoint.y - viaPoint.y, nextPoint.x - viaPoint.x)
 
@@ -15,7 +26,9 @@ public extension Path {
 
         let offsetEnd2 = CGPoint(x: nextPoint.x + nextLineVector.dx, y: nextPoint.y + nextLineVector.dy)
 
-        let intersection = CGPoint.intersection(start1: offsetStart1, end1: offsetEnd1, start2: offsetStart2, end2: offsetEnd2)
+        guard let intersection = CGPoint.intersection(start1: offsetStart1, end1: offsetEnd1, start2: offsetStart2, end2: offsetEnd2) else {
+            return
+        }
 
         let startAngle = lineAngle - (.pi / 2)
         let endAngle = nextLineAngle - (.pi / 2)
@@ -24,8 +37,10 @@ public extension Path {
             center: intersection,
             radius: radius,
             startAngle: Angle(radians: startAngle),
-            endAngle: Angle(radians:endAngle),
-            clockwise: clockwise
+            endAngle: Angle(radians: endAngle),
+            clockwise: isClockwise
         )
     }
 }
+
+

Sources/Shapes/RoundedRegularPolygons/RoundedRegularPolygonPath.swift

@@ -50,7 +50,7 @@ extension Path {
                     y: centerPoint.y + CGFloat(sin(nextAngle) * hypotenuse)
                 )
 
-                path.addCircularCornerRadiusArc(from: point, via: viaPoint, to: nextPoint, radius: usableRadius, clockwise: false)
+                path.addCircularCornerRadiusArc(from: point, via: viaPoint, to: nextPoint, radius: usableRadius)
             }
             path.closeSubpath()
         }

Sources/Shapes/RoundedStarPolygons/RoundedStarPolygon.swift

@@ -102,9 +102,9 @@ extension Path {
 
                 let lastPoint: CGPoint = getLastPoint(from: centerPoint, angle: lastAngle, hypotenuse: hypotenuse, smoothness: smoothness)
 
-                path.addCircularCornerRadiusArc(from: point, via: viaPoint, to: nextPoint, radius: smoothness > 0.5 ? usableConcaveRadius: -usableConcaveRadius, clockwise: smoothness > 0.5 ? false : true)
+                path.addCircularCornerRadiusArc(from: point, via: viaPoint, to: nextPoint, radius: usableConcaveRadius)
 
-                path.addCircularCornerRadiusArc(from: viaPoint, via: nextPoint, to: lastPoint, radius: usableConvexRadius, clockwise: false)
+                path.addCircularCornerRadiusArc(from: viaPoint, via: nextPoint, to: lastPoint, radius: usableConvexRadius)
             }
             path.closeSubpath()
         }
@@ -120,6 +120,11 @@ struct RoundedStarPolygon_Previews: PreviewProvider {
             .background(Circle())
             .previewLayout(.fixed(width: 400, height: 400))
 
+        RoundedStarPolygon(points: 12, smoothness: 0.87, radius: 20) .strokeBorder(lineWidth: 1)
+            .foregroundColor(.yellow)
+            .background(Circle())
+            .previewLayout(.fixed(width: 400, height: 400))
+        
         RoundedStarPolygon(points: 3, smoothness: 0.87, radius: 40)
             .fill(Color.orange)
             .background(Circle())