spine-runtimes/spine-ts/spine-core/src/SkeletonClipping.ts

597 lines
22 KiB
TypeScript

/******************************************************************************
* Spine Runtimes License Agreement
* Last updated April 5, 2025. Replaces all prior versions.
*
* Copyright (c) 2013-2025, Esoteric Software LLC
*
* Integration of the Spine Runtimes into software or otherwise creating
* derivative works of the Spine Runtimes is permitted under the terms and
* conditions of Section 2 of the Spine Editor License Agreement:
* http://esotericsoftware.com/spine-editor-license
*
* Otherwise, it is permitted to integrate the Spine Runtimes into software
* or otherwise create derivative works of the Spine Runtimes (collectively,
* "Products"), provided that each user of the Products must obtain their own
* Spine Editor license and redistribution of the Products in any form must
* include this license and copyright notice.
*
* THE SPINE RUNTIMES ARE PROVIDED BY ESOTERIC SOFTWARE LLC "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL ESOTERIC SOFTWARE LLC BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES,
* BUSINESS INTERRUPTION, OR LOSS OF USE, DATA, OR PROFITS) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THE SPINE RUNTIMES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*****************************************************************************/
import type { ClippingAttachment } from "./attachments/ClippingAttachment.js";
import type { Skeleton } from "./Skeleton.js";
import type { Slot } from "./Slot.js";
import { Triangulator } from "./Triangulator.js";
import { type Color, type NumberArrayLike, Utils } from "./Utils.js";
export class SkeletonClipping {
private triangulator = new Triangulator();
private clippingPolygon = [] as number[];
private clipOutput = [] as number[];
clippedVertices = [] as number[];
/** An empty array unless {@link clipTrianglesUnpacked} was used. **/
clippedUVs = [] as number[];
clippedTriangles = [] as number[];
_clippedVerticesTyped = new Float32Array(1024);
_clippedUVsTyped = new Float32Array(1024);
_clippedTrianglesTyped = new Uint32Array(1024);
clippedVerticesTyped = new Float32Array(0);
clippedUVsTyped = new Float32Array(0);
clippedTrianglesTyped = new Uint32Array(0);
clippedVerticesLength = 0;
clippedUVsLength = 0;
clippedTrianglesLength = 0;
private scratch = [] as number[];
private clipAttachment: ClippingAttachment | null = null;
private clippingPolygons: Array<Array<number>> | null = null;
clipStart (skeleton: Skeleton, slot: Slot, clip: ClippingAttachment): number {
if (this.clipAttachment) return 0;
this.clipAttachment = clip;
const n = clip.worldVerticesLength;
const vertices = Utils.setArraySize(this.clippingPolygon, n);
clip.computeWorldVertices(skeleton, slot, 0, n, vertices, 0, 2);
const clippingPolygon = this.clippingPolygon;
SkeletonClipping.makeClockwise(clippingPolygon);
const clippingPolygons = this.clippingPolygons = this.triangulator.decompose(clippingPolygon, this.triangulator.triangulate(clippingPolygon));
for (let i = 0, n = clippingPolygons.length; i < n; i++) {
const polygon = clippingPolygons[i];
SkeletonClipping.makeClockwise(polygon);
polygon.push(polygon[0]);
polygon.push(polygon[1]);
}
return clippingPolygons.length;
}
clipEnd (slot?: Slot) {
if (!this.clipAttachment) return;
if (slot && this.clipAttachment.endSlot !== slot.data) return;
this.clipAttachment = null;
this.clippingPolygons = null;
this.clippedVertices.length = 0;
this.clippedTriangles.length = 0;
this.clippingPolygon.length = 0;
this.clippedVerticesLength = 0;
this.clippedUVsLength = 0;
this.clippedTrianglesLength = 0;
}
isClipping (): boolean {
return this.clipAttachment != null;
}
clipTriangles (vertices: NumberArrayLike, triangles: NumberArrayLike, trianglesLength: number): boolean;
clipTriangles (vertices: NumberArrayLike, triangles: NumberArrayLike, trianglesLength: number,
uvs: NumberArrayLike, light: Color, dark: Color, twoColor: boolean, stride: number): boolean;
clipTriangles (vertices: NumberArrayLike, triangles: NumberArrayLike, trianglesLength: number,
uvs?: NumberArrayLike, light?: Color, dark?: Color, twoColor?: boolean, stride?: number): boolean {
return (uvs && light && dark && typeof twoColor === 'boolean' && typeof stride === 'number')
? this.clipTrianglesRender(vertices, triangles, trianglesLength, uvs, light, dark, twoColor, stride)
: this.clipTrianglesNoRender(vertices, triangles, trianglesLength);
}
private clipTrianglesNoRender (vertices: NumberArrayLike, triangles: NumberArrayLike, trianglesLength: number): boolean {
const clipOutput = this.clipOutput, clippedVertices = this.clippedVertices;
const clippedTriangles = this.clippedTriangles;
// biome-ignore lint/style/noNonNullAssertion: clipStart define it
const polygons = this.clippingPolygons!;
const polygonsCount = polygons.length;
let index = 0;
clippedVertices.length = 0;
clippedTriangles.length = 0;
let clipOutputItems = null;
for (let i = 0; i < trianglesLength; i += 3) {
let v = triangles[i] << 1;
const x1 = vertices[v], y1 = vertices[v + 1];
v = triangles[i + 1] << 1;
const x2 = vertices[v], y2 = vertices[v + 1];
v = triangles[i + 2] << 1;
const x3 = vertices[v], y3 = vertices[v + 1];
for (let p = 0; p < polygonsCount; p++) {
let s = clippedVertices.length;
if (this.clip(x1, y1, x2, y2, x3, y3, polygons[p], clipOutput)) {
clipOutputItems = this.clipOutput;
const clipOutputLength = clipOutput.length;
if (clipOutputLength === 0) continue;
let clipOutputCount = clipOutputLength >> 1;
const clippedVerticesItems = Utils.setArraySize(clippedVertices, s + clipOutputCount * 2);
for (let ii = 0; ii < clipOutputLength; ii += 2, s += 2) {
const x = clipOutputItems[ii], y = clipOutputItems[ii + 1];
clippedVerticesItems[s] = x;
clippedVerticesItems[s + 1] = y;
}
s = clippedTriangles.length;
const clippedTrianglesItems = Utils.setArraySize(clippedTriangles, s + 3 * (clipOutputCount - 2));
clipOutputCount--;
for (let ii = 1; ii < clipOutputCount; ii++, s += 3) {
clippedTrianglesItems[s] = index;
clippedTrianglesItems[s + 1] = (index + ii);
clippedTrianglesItems[s + 2] = (index + ii + 1);
}
index += clipOutputCount + 1;
} else {
const clippedVerticesItems = Utils.setArraySize(clippedVertices, s + 3 * 2);
clippedVerticesItems[s] = x1;
clippedVerticesItems[s + 1] = y1;
clippedVerticesItems[s + 2] = x2;
clippedVerticesItems[s + 3] = y2;
clippedVerticesItems[s + 4] = x3;
clippedVerticesItems[s + 5] = y3;
s = clippedTriangles.length;
const clippedTrianglesItems = Utils.setArraySize(clippedTriangles, s + 3);
clippedTrianglesItems[s] = index;
clippedTrianglesItems[s + 1] = (index + 1);
clippedTrianglesItems[s + 2] = (index + 2);
index += 3;
break;
}
}
}
return clipOutputItems != null;
}
private clipTrianglesRender (vertices: NumberArrayLike, triangles: NumberArrayLike, trianglesLength: number, uvs: NumberArrayLike,
light: Color, dark: Color, twoColor: boolean, stride: number): boolean {
const clipOutput = this.clipOutput, clippedVertices = this.clippedVertices;
const clippedTriangles = this.clippedTriangles;
// biome-ignore lint/style/noNonNullAssertion: clipStart define it
const polygons = this.clippingPolygons!;
const polygonsCount = polygons.length;
let index = 0;
clippedVertices.length = 0;
clippedTriangles.length = 0;
let clipOutputItems = null;
for (let i = 0; i < trianglesLength; i += 3) {
let t = triangles[i];
const u1 = uvs[t << 1], v1 = uvs[(t << 1) + 1];
const x1 = vertices[t * stride], y1 = vertices[t * stride + 1];
t = triangles[i + 1];
const u2 = uvs[t << 1], v2 = uvs[(t << 1) + 1];
const x2 = vertices[t * stride], y2 = vertices[t * stride + 1];
t = triangles[i + 2];
const u3 = uvs[t << 1], v3 = uvs[(t << 1) + 1];
const x3 = vertices[t * stride], y3 = vertices[t * stride + 1];
for (let p = 0; p < polygonsCount; p++) {
let s = clippedVertices.length;
if (this.clip(x1, y1, x2, y2, x3, y3, polygons[p], clipOutput)) {
clipOutputItems = this.clipOutput;
const clipOutputLength = clipOutput.length;
if (clipOutputLength === 0) continue;
const d0 = y2 - y3, d1 = x3 - x2, d2 = x1 - x3, d4 = y3 - y1;
const d = 1 / (d0 * d2 + d1 * (y1 - y3));
let clipOutputCount = clipOutputLength >> 1;
const clippedVerticesItems = Utils.setArraySize(clippedVertices, s + clipOutputCount * stride);
for (let ii = 0; ii < clipOutputLength; ii += 2, s += stride) {
const x = clipOutputItems[ii], y = clipOutputItems[ii + 1];
clippedVerticesItems[s] = x;
clippedVerticesItems[s + 1] = y;
clippedVerticesItems[s + 2] = light.r;
clippedVerticesItems[s + 3] = light.g;
clippedVerticesItems[s + 4] = light.b;
clippedVerticesItems[s + 5] = light.a;
const c0 = x - x3, c1 = y - y3;
const a = (d0 * c0 + d1 * c1) * d;
const b = (d4 * c0 + d2 * c1) * d;
const c = 1 - a - b;
clippedVerticesItems[s + 6] = u1 * a + u2 * b + u3 * c;
clippedVerticesItems[s + 7] = v1 * a + v2 * b + v3 * c;
if (twoColor) {
clippedVerticesItems[s + 8] = dark.r;
clippedVerticesItems[s + 9] = dark.g;
clippedVerticesItems[s + 10] = dark.b;
clippedVerticesItems[s + 11] = dark.a;
}
}
s = clippedTriangles.length;
const clippedTrianglesItems = Utils.setArraySize(clippedTriangles, s + 3 * (clipOutputCount - 2));
clipOutputCount--;
for (let ii = 1; ii < clipOutputCount; ii++, s += 3) {
clippedTrianglesItems[s] = index;
clippedTrianglesItems[s + 1] = (index + ii);
clippedTrianglesItems[s + 2] = (index + ii + 1);
}
index += clipOutputCount + 1;
} else {
const clippedVerticesItems = Utils.setArraySize(clippedVertices, s + 3 * stride);
clippedVerticesItems[s] = x1;
clippedVerticesItems[s + 1] = y1;
clippedVerticesItems[s + 2] = light.r;
clippedVerticesItems[s + 3] = light.g;
clippedVerticesItems[s + 4] = light.b;
clippedVerticesItems[s + 5] = light.a;
if (!twoColor) {
clippedVerticesItems[s + 6] = u1;
clippedVerticesItems[s + 7] = v1;
clippedVerticesItems[s + 8] = x2;
clippedVerticesItems[s + 9] = y2;
clippedVerticesItems[s + 10] = light.r;
clippedVerticesItems[s + 11] = light.g;
clippedVerticesItems[s + 12] = light.b;
clippedVerticesItems[s + 13] = light.a;
clippedVerticesItems[s + 14] = u2;
clippedVerticesItems[s + 15] = v2;
clippedVerticesItems[s + 16] = x3;
clippedVerticesItems[s + 17] = y3;
clippedVerticesItems[s + 18] = light.r;
clippedVerticesItems[s + 19] = light.g;
clippedVerticesItems[s + 20] = light.b;
clippedVerticesItems[s + 21] = light.a;
clippedVerticesItems[s + 22] = u3;
clippedVerticesItems[s + 23] = v3;
} else {
clippedVerticesItems[s + 6] = u1;
clippedVerticesItems[s + 7] = v1;
clippedVerticesItems[s + 8] = dark.r;
clippedVerticesItems[s + 9] = dark.g;
clippedVerticesItems[s + 10] = dark.b;
clippedVerticesItems[s + 11] = dark.a;
clippedVerticesItems[s + 12] = x2;
clippedVerticesItems[s + 13] = y2;
clippedVerticesItems[s + 14] = light.r;
clippedVerticesItems[s + 15] = light.g;
clippedVerticesItems[s + 16] = light.b;
clippedVerticesItems[s + 17] = light.a;
clippedVerticesItems[s + 18] = u2;
clippedVerticesItems[s + 19] = v2;
clippedVerticesItems[s + 20] = dark.r;
clippedVerticesItems[s + 21] = dark.g;
clippedVerticesItems[s + 22] = dark.b;
clippedVerticesItems[s + 23] = dark.a;
clippedVerticesItems[s + 24] = x3;
clippedVerticesItems[s + 25] = y3;
clippedVerticesItems[s + 26] = light.r;
clippedVerticesItems[s + 27] = light.g;
clippedVerticesItems[s + 28] = light.b;
clippedVerticesItems[s + 29] = light.a;
clippedVerticesItems[s + 30] = u3;
clippedVerticesItems[s + 31] = v3;
clippedVerticesItems[s + 32] = dark.r;
clippedVerticesItems[s + 33] = dark.g;
clippedVerticesItems[s + 34] = dark.b;
clippedVerticesItems[s + 35] = dark.a;
}
s = clippedTriangles.length;
const clippedTrianglesItems = Utils.setArraySize(clippedTriangles, s + 3);
clippedTrianglesItems[s] = index;
clippedTrianglesItems[s + 1] = (index + 1);
clippedTrianglesItems[s + 2] = (index + 2);
index += 3;
break;
}
}
}
return clipOutputItems != null;
}
public clipTrianglesUnpacked (vertices: NumberArrayLike, triangles: NumberArrayLike | Uint32Array, trianglesLength: number, uvs: NumberArrayLike, stride = 2) {
const clipOutput = this.clipOutput;
let clippedVertices = this._clippedVerticesTyped, clippedUVs = this._clippedUVsTyped, clippedTriangles = this._clippedTrianglesTyped;
// biome-ignore lint/style/noNonNullAssertion: clipStart define it
const polygons = this.clippingPolygons!;
const polygonsCount = polygons.length;
let index = 0;
this.clippedVerticesLength = 0;
this.clippedUVsLength = 0;
this.clippedTrianglesLength = 0;
this._clippedVerticesTyped;
this._clippedUVsTyped;
this._clippedTrianglesTyped;
let clipped = false;
for (let i = 0; i < trianglesLength; i += 3) {
let t = triangles[i];
let v = t * stride;
const x1 = vertices[v], y1 = vertices[v + 1];
let uv = t << 1;
const u1 = uvs[uv], v1 = uvs[uv + 1];
t = triangles[i + 1];
v = t * stride;
const x2 = vertices[v], y2 = vertices[v + 1];
uv = t << 1;
const u2 = uvs[uv], v2 = uvs[uv + 1];
t = triangles[i + 2];
v = t * stride;
const x3 = vertices[v], y3 = vertices[v + 1];
uv = t << 1;
const u3 = uvs[uv], v3 = uvs[uv + 1];
for (let p = 0; p < polygonsCount; p++) {
let s = this.clippedVerticesLength;
if (this.clip(x1, y1, x2, y2, x3, y3, polygons[p], clipOutput)) {
const clipOutputLength = clipOutput.length;
if (clipOutputLength === 0) continue;
clipped = true;
const d0 = y2 - y3, d1 = x3 - x2, d2 = x1 - x3, d4 = y3 - y1;
const d = 1 / (d0 * d2 + d1 * (y1 - y3));
let clipOutputCount = clipOutputLength >> 1;
const clipOutputItems = this.clipOutput;
const newLength = s + clipOutputCount * stride;
if (clippedVertices.length < newLength) {
this._clippedVerticesTyped = new Float32Array(newLength * 2);
this._clippedVerticesTyped.set(clippedVertices.subarray(0, s));
this._clippedUVsTyped = new Float32Array((this.clippedUVsLength + clipOutputCount * 2) * 2);
this._clippedUVsTyped.set(clippedUVs.subarray(0, this.clippedUVsLength));
clippedVertices = this._clippedVerticesTyped;
clippedUVs = this._clippedUVsTyped;
}
const clippedVerticesItems = clippedVertices;
const clippedUVsItems = clippedUVs;
this.clippedVerticesLength = newLength;
let uvIndex = this.clippedUVsLength;
this.clippedUVsLength = uvIndex + clipOutputCount * 2;
for (let ii = 0; ii < clipOutputLength; ii += 2, s += stride, uvIndex += 2) {
const x = clipOutputItems[ii], y = clipOutputItems[ii + 1];
clippedVerticesItems[s] = x;
clippedVerticesItems[s + 1] = y;
const c0 = x - x3, c1 = y - y3;
const a = (d0 * c0 + d1 * c1) * d;
const b = (d4 * c0 + d2 * c1) * d;
const c = 1 - a - b;
clippedUVsItems[uvIndex] = u1 * a + u2 * b + u3 * c;
clippedUVsItems[uvIndex + 1] = v1 * a + v2 * b + v3 * c;
}
s = this.clippedTrianglesLength;
const newLengthTriangles = s + 3 * (clipOutputCount - 2)
if (clippedTriangles.length < newLengthTriangles) {
this._clippedTrianglesTyped = new Uint32Array(newLengthTriangles * 2);
this._clippedTrianglesTyped.set(clippedTriangles.subarray(0, s));
clippedTriangles = this._clippedTrianglesTyped;
}
this.clippedTrianglesLength = newLengthTriangles;
const clippedTrianglesItems = clippedTriangles;
clipOutputCount--;
for (let ii = 1; ii < clipOutputCount; ii++, s += 3) {
clippedTrianglesItems[s] = index;
clippedTrianglesItems[s + 1] = (index + ii);
clippedTrianglesItems[s + 2] = (index + ii + 1);
}
index += clipOutputCount + 1;
} else {
let newLength = s + 3 * stride;
if (clippedVertices.length < newLength) {
this._clippedVerticesTyped = new Float32Array(newLength * 2);
this._clippedVerticesTyped.set(clippedVertices.subarray(0, s));
clippedVertices = this._clippedVerticesTyped;
}
clippedVertices[s] = x1;
clippedVertices[s + 1] = y1;
clippedVertices[s + stride] = x2;
clippedVertices[s + stride + 1] = y2;
clippedVertices[s + stride * 2] = x3;
clippedVertices[s + stride * 2 + 1] = y3;
let uvLength = this.clippedUVsLength + 3 * 2;
if (clippedUVs.length < uvLength) {
this._clippedUVsTyped = new Float32Array(uvLength * 2);
this._clippedUVsTyped.set(clippedUVs.subarray(0, this.clippedUVsLength));
clippedUVs = this._clippedUVsTyped;
}
let uvIndex = this.clippedUVsLength;
clippedUVs[uvIndex] = u1;
clippedUVs[uvIndex + 1] = v1;
clippedUVs[uvIndex + 2] = u2;
clippedUVs[uvIndex + 3] = v2;
clippedUVs[uvIndex + 4] = u3;
clippedUVs[uvIndex + 5] = v3;
this.clippedVerticesLength = newLength;
this.clippedUVsLength = uvLength;
s = this.clippedTrianglesLength;
newLength = s + 3;
if (clippedTriangles.length < newLength) {
this._clippedTrianglesTyped = new Uint32Array(newLength * 2);
this._clippedTrianglesTyped.set(clippedTriangles.subarray(0, s));
clippedTriangles = this._clippedTrianglesTyped;
}
clippedTriangles[s] = index;
clippedTriangles[s + 1] = (index + 1);
clippedTriangles[s + 2] = (index + 2);
index += 3;
this.clippedTrianglesLength = newLength;
break;
}
}
}
this.clippedVerticesTyped = this._clippedVerticesTyped.subarray(0, this.clippedVerticesLength)
this.clippedUVsTyped = this._clippedUVsTyped.subarray(0, this.clippedUVsLength)
this.clippedTrianglesTyped = this._clippedTrianglesTyped.subarray(0, this.clippedTrianglesLength)
return clipped;
}
/** Clips the input triangle against the convex, clockwise clipping area. If the triangle lies entirely within the clipping
* area, false is returned. The clipping area must duplicate the first vertex at the end of the vertices list. */
private clip (x1: number, y1: number, x2: number, y2: number, x3: number, y3: number, clippingArea: Array<number>, output: Array<number>) {
const originalOutput = output;
let clipped = false;
// Avoid copy at the end.
let input: Array<number>;
if (clippingArea.length % 4 >= 2) {
input = output;
output = this.scratch;
} else
input = this.scratch;
input.length = 0;
input.push(x1);
input.push(y1);
input.push(x2);
input.push(y2);
input.push(x3);
input.push(y3);
input.push(x1);
input.push(y1);
output.length = 0;
const clippingVerticesLast = clippingArea.length - 4;
const clippingVertices = clippingArea;
for (let i = 0; ; i += 2) {
const edgeX = clippingVertices[i], edgeY = clippingVertices[i + 1];
const ex = edgeX - clippingVertices[i + 2], ey = edgeY - clippingVertices[i + 3];
const outputStart = output.length;
const inputVertices = input;
for (let ii = 0, nn = input.length - 2; ii < nn;) {
const inputX = inputVertices[ii], inputY = inputVertices[ii + 1];
ii += 2;
const inputX2 = inputVertices[ii], inputY2 = inputVertices[ii + 1];
const s2 = ey * (edgeX - inputX2) > ex * (edgeY - inputY2);
const s1 = ey * (edgeX - inputX) - ex * (edgeY - inputY);
if (s1 > 0) {
if (s2) { // v1 inside, v2 inside
output.push(inputX2);
output.push(inputY2);
continue;
}
// v1 inside, v2 outside
const ix = inputX2 - inputX, iy = inputY2 - inputY, t = s1 / (ix * ey - iy * ex);
if (t >= 0 && t <= 1) {
output.push(inputX + ix * t);
output.push(inputY + iy * t);
} else {
output.push(inputX2);
output.push(inputY2);
continue;
}
} else if (s2) { // v1 outside, v2 inside
const ix = inputX2 - inputX, iy = inputY2 - inputY, t = s1 / (ix * ey - iy * ex);
if (t >= 0 && t <= 1) {
output.push(inputX + ix * t);
output.push(inputY + iy * t);
output.push(inputX2);
output.push(inputY2);
} else {
output.push(inputX2);
output.push(inputY2);
continue;
}
}
clipped = true;
}
if (outputStart === output.length) { // All edges outside.
originalOutput.length = 0;
return true;
}
output.push(output[0]);
output.push(output[1]);
if (i === clippingVerticesLast) break;
const temp = output;
output = input;
output.length = 0;
input = temp;
}
if (originalOutput !== output) {
originalOutput.length = 0;
for (let i = 0, n = output.length - 2; i < n; i++)
originalOutput[i] = output[i];
} else
originalOutput.length = originalOutput.length - 2;
return clipped;
}
public static makeClockwise (polygon: NumberArrayLike) {
const vertices = polygon;
const verticeslength = polygon.length;
let area = vertices[verticeslength - 2] * vertices[1] - vertices[0] * vertices[verticeslength - 1], p1x = 0, p1y = 0, p2x = 0, p2y = 0;
for (let i = 0, n = verticeslength - 3; i < n; i += 2) {
p1x = vertices[i];
p1y = vertices[i + 1];
p2x = vertices[i + 2];
p2y = vertices[i + 3];
area += p1x * p2y - p2x * p1y;
}
if (area < 0) return;
for (let i = 0, lastX = verticeslength - 2, n = verticeslength >> 1; i < n; i += 2) {
const x = vertices[i], y = vertices[i + 1];
const other = lastX - i;
vertices[i] = vertices[other];
vertices[i + 1] = vertices[other + 1];
vertices[other] = x;
vertices[other + 1] = y;
}
}
}