新增polygonmesh

source/src/ECS/Components/Mesh.ts

@@ -0,0 +1,54 @@
+class Mesh extends Component {
+    private _verts: VertexPosition[];
+    private _primitiveCount: number;
+    private _triangles: number[];
+    private _topLeftVertPosition: Vector2;
+    private _width;
+    private _height;
+
+    public initialize() {
+    }
+    
+    public setVertPosition(positions: Vector2[]){
+        let createVerts = !this._verts || this._verts.length != positions.length;
+        if (createVerts)
+            this._verts = new Array(positions.length);
+
+        for (let i = 0; i < this._verts.length; i ++){
+            this._verts[i] = new VertexPosition(positions[i]);
+        }
+
+        return this;
+    }
+
+    public setTriangles(triangles: number[]){
+        this._primitiveCount = triangles.length / 3;
+        this._triangles = triangles;
+        return this;
+    }
+
+    public recalculateBounds(){
+        this._topLeftVertPosition = new Vector2(Number.MAX_VALUE, Number.MAX_VALUE);
+        let max = new Vector2(Number.MIN_VALUE, Number.MIN_VALUE);
+
+        for (let i = 0; i < this._verts.length; i ++){
+            this._topLeftVertPosition.x = Math.min(this._topLeftVertPosition.x, this._verts[i].position.x);
+            this._topLeftVertPosition.y = Math.min(this._topLeftVertPosition.y, this._verts[i].position.y);
+            max.x = Math.max(max.x, this._verts[i].position.x);
+            max.y = Math.max(max.y, this._verts[i].position.y);
+        }
+
+        this._width = max.x - this._topLeftVertPosition.x;
+        this._height = max.y - this._topLeftVertPosition.y;
+
+        return this;
+    }
+}
+
+class VertexPosition{
+    public position: Vector2;
+    
+    constructor(position: Vector2){
+        this.position = position;
+    }
+}

source/src/ECS/Components/PolygonMesh.ts

@@ -0,0 +1,12 @@
+class PolygonMesh extends Mesh {
+    constructor(points: Vector2[], arePointsCCW: boolean = true){
+        super();
+
+        let triangulator = new Triangulator();
+        triangulator.triangulate(points, arePointsCCW);
+
+        this.setVertPosition(points);
+        this.setTriangles(triangulator.triangleIndices);
+        this.recalculateBounds();
+    }
+}

source/src/Utils/Triangulator.ts

@@ -0,0 +1,111 @@
+/**
+ * 三角剖分
+ */
+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);
+
+    /**
+     * 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;
+    }
+
+    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;
+    }
+}

source/src/Utils/Vector2Ext.ts

@@ -0,0 +1,20 @@
+class Vector2Ext {
+    /**
+     * 检查三角形是CCW还是CW
+     * @param a 
+     * @param center 
+     * @param c 
+     */
+    public static isTriangleCCW(a: Vector2, center: Vector2, c: Vector2){
+        return this.cross(Vector2.subtract(center, a), Vector2.subtract(c, center)) < 0;
+    }
+
+    /**
+     * 计算二维伪叉乘点(Perp(u)， v)
+     * @param u 
+     * @param v 
+     */
+    public static cross(u: Vector2, v: Vector2){
+        return u.y * v.x - u.x * v.y;
+    }
+}