114 lines
4.0 KiB
TypeScript
114 lines
4.0 KiB
TypeScript
module es {
|
||
/**
|
||
* 三角剖分
|
||
*/
|
||
export class Triangulator {
|
||
/**
|
||
* 最后一次三角调用中使用的点列表的三角形列表项的索引
|
||
*/
|
||
public triangleIndices: number[] = [];
|
||
|
||
private _triPrev: number[] = new Array<number>(12);
|
||
private _triNext: number[] = new Array<number>(12);
|
||
|
||
public static testPointTriangle(point: Vector2, a: Vector2, b: Vector2, c: Vector2): boolean {
|
||
if (Vector2Ext.cross(Vector2.subtract(point, a), Vector2.subtract(b, a)) < 0)
|
||
return false;
|
||
|
||
if (Vector2Ext.cross(Vector2.subtract(point, b), Vector2.subtract(c, b)) < 0)
|
||
return false;
|
||
|
||
if (Vector2Ext.cross(Vector2.subtract(point, c), Vector2.subtract(a, c)) < 0)
|
||
return false;
|
||
|
||
return true;
|
||
}
|
||
|
||
/**
|
||
* 计算一个三角形列表，该列表完全覆盖给定点集所包含的区域。如果点不是CCW，则将arePointsCCW参数传递为false
|
||
* @param points 定义封闭路径的点列表
|
||
* @param arePointsCCW
|
||
*/
|
||
public triangulate(points: Vector2[], arePointsCCW: boolean = true) {
|
||
let count = points.length;
|
||
|
||
// 设置前一个链接和下一个链接
|
||
this.initialize(count);
|
||
|
||
// 非三角的多边形断路器
|
||
let iterations = 0;
|
||
|
||
// 从0开始
|
||
let index = 0;
|
||
|
||
// 继续移除所有的三角形，直到只剩下一个三角形
|
||
while (count > 3 && iterations < 500) {
|
||
iterations++;
|
||
|
||
let isEar = true;
|
||
let a = points[this._triPrev[index]];
|
||
let b = points[index];
|
||
let c = points[this._triNext[index]];
|
||
|
||
if (Vector2Ext.isTriangleCCW(a, b, c)) {
|
||
let k = this._triNext[this._triNext[index]];
|
||
do {
|
||
if (Triangulator.testPointTriangle(points[k], a, b, c)) {
|
||
isEar = false;
|
||
break;
|
||
}
|
||
|
||
k = this._triNext[k];
|
||
} while (k != this._triPrev[index]);
|
||
} else {
|
||
isEar = false;
|
||
}
|
||
|
||
if (isEar) {
|
||
this.triangleIndices.push(this._triPrev[index]);
|
||
this.triangleIndices.push(index);
|
||
this.triangleIndices.push(this._triNext[index]);
|
||
|
||
// 删除vert通过重定向相邻vert的上一个和下一个链接，从而减少vertext计数
|
||
this._triNext[this._triPrev[index]] = this._triNext[index];
|
||
this._triPrev[this._triNext[index]] = this._triPrev[index];
|
||
count--;
|
||
|
||
// 接下来访问前一个vert
|
||
index = this._triPrev[index];
|
||
} else {
|
||
index = this._triNext[index];
|
||
}
|
||
}
|
||
|
||
this.triangleIndices.push(this._triPrev[index]);
|
||
this.triangleIndices.push(index);
|
||
this.triangleIndices.push(this._triNext[index]);
|
||
|
||
if (!arePointsCCW)
|
||
this.triangleIndices.reverse();
|
||
}
|
||
|
||
private initialize(count: number) {
|
||
this.triangleIndices.length = 0;
|
||
|
||
if (this._triNext.length < count) {
|
||
this._triNext.reverse();
|
||
this._triNext = new Array<number>(Math.max(this._triNext.length * 2, count));
|
||
}
|
||
if (this._triPrev.length < count) {
|
||
this._triPrev.reverse();
|
||
this._triPrev = new Array<number>(Math.max(this._triPrev.length * 2, count));
|
||
}
|
||
|
||
for (let i = 0; i < count; i++) {
|
||
this._triPrev[i] = i - 1;
|
||
this._triNext[i] = i + 1;
|
||
}
|
||
|
||
this._triPrev[0] = count - 1;
|
||
this._triNext[count - 1] = 0;
|
||
}
|
||
}
|
||
}
|