feat: EquilateralPloygonCurve

src/core/Path2D.ts

@@ -301,11 +301,11 @@ export class Path2D extends CompositeCurve<CurvePath> {
   }
 
   toCommands(): Path2DCommand[] {
-    return this.curves.flatMap(path => path.toCommands())
+    return this.curves.flatMap(v => v.toCommands())
   }
 
   toData(): Path2DData {
-    return this.curves.map(path => path.toData()).join(' ')
+    return this.curves.filter(v => v.curves.length).map(v => v.toData()).join(' ')
   }
 
   toSVGPathString(): string {

src/curve/ArcCurve.ts

@@ -3,12 +3,12 @@ import { EllipseCurve } from './EllipseCurve'
 export class ArcCurve extends EllipseCurve {
   constructor(
     cx = 0, cy = 0,
-    r = 1,
+    radius = 1,
     startAngle = 0,
     endAngle = Math.PI * 2,
     clockwise = false,
   ) {
-    super(cx, cy, r, r, 0, startAngle, endAngle, clockwise)
+    super(cx, cy, radius, radius, 0, startAngle, endAngle, clockwise)
   }
 
   override getAdaptivePointArray(output: number[] = []): number[] {

src/curve/PloygonCurve.ts

@@ -1,6 +1,31 @@
-import type { LineCurve } from './LineCurve'
+import { Vector2 } from '../math'
 import { CompositeCurve } from './CompositeCurve'
+import { LineCurve } from './LineCurve'
 
 export class PloygonCurve extends CompositeCurve<LineCurve> {
-  //
+  static equilateral(
+    cx = 0,
+    cy = 0,
+    radius = 1,
+    sideCount = 3,
+  ): PloygonCurve {
+    const ploygon = new PloygonCurve()
+    const points: Vector2[] = []
+    for (let i = 0; i < sideCount; i++) {
+      const radian = (i * 2 * Math.PI) / sideCount - 0.5 * Math.PI
+      points.push(
+        new Vector2(
+          radius * Math.cos(radian),
+          radius * Math.sin(radian),
+        )
+          .add({ x: cx, y: cy }),
+      )
+    }
+    for (let i = 0; i < sideCount; i++) {
+      ploygon.curves.push(
+        LineCurve.from(points[i], points[(i + 1) % sideCount]),
+      )
+    }
+    return ploygon
+  }
 }