103 lines
4.1 KiB
TypeScript
103 lines
4.1 KiB
TypeScript
module es {
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export class ShapeCollisionsPolygon {
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/**
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* 检查两个多边形之间的碰撞
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* @param first
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* @param second
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* @param result
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*/
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public static polygonToPolygon(first: Polygon, second: Polygon, result: CollisionResult): boolean {
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let isIntersecting = true;
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const firstEdges = first.edgeNormals;
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const secondEdges = second.edgeNormals;
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let minIntervalDistance = Number.POSITIVE_INFINITY;
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let translationAxis = Vector2.zero;
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let polygonOffset = first.position.sub(second.position);
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let axis: Vector2;
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// 循环穿过两个多边形的所有边
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for (let edgeIndex = 0; edgeIndex < firstEdges.length + secondEdges.length; edgeIndex++) {
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// 1. 找出当前多边形是否相交
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// 多边形的归一化轴垂直于缓存给我们的当前边
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axis = edgeIndex < firstEdges.length ? firstEdges[edgeIndex] : secondEdges[edgeIndex - firstEdges.length];
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// 求多边形在当前轴上的投影
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let intervalDist = 0;
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let {min: minA, max: maxA} = this.getInterval(axis, first);
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const {min: minB, max: maxB} = this.getInterval(axis, second);
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// 将区间设为第二个多边形的空间。由轴上投影的位置差偏移。
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const relativeIntervalOffset = polygonOffset.dot(axis);
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minA += relativeIntervalOffset;
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maxA += relativeIntervalOffset;
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// 检查多边形投影是否正在相交
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intervalDist = this.intervalDistance(minA, maxA, minB, maxB);
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if (intervalDist > 0)
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isIntersecting = false;
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// 对于多对多数据类型转换，添加一个Vector2?参数称为deltaMovement。为了提高速度，我们这里不使用它
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// TODO: 现在找出多边形是否会相交。只要检查速度就行了
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// 如果多边形不相交，也不会相交，退出循环
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if (!isIntersecting)
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return false;
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// 检查当前间隔距离是否为最小值。如果是，则存储间隔距离和当前距离。这将用于计算最小平移向量
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intervalDist = Math.abs(intervalDist);
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if (intervalDist < minIntervalDistance) {
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minIntervalDistance = intervalDist;
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translationAxis.setTo(axis.x, axis.y);
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if (translationAxis.dot(polygonOffset) < 0)
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translationAxis = translationAxis.scale(-1);
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}
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}
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// 利用最小平移向量对多边形进行推入。
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result.normal = translationAxis;
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result.minimumTranslationVector = translationAxis.scale(-minIntervalDistance);
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return true;
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}
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/**
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* 计算一个多边形在一个轴上的投影，并返回一个[min，max]区间
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* @param axis
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* @param polygon
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* @param min
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* @param max
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*/
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public static getInterval(axis: Vector2, polygon: Polygon): {min: number, max: number} {
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const res = {min: 0, max: 0};
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let dot: number;
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dot = polygon.points[0].dot(axis);
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res.max = dot;
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res.min = dot;
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for (let i = 1; i < polygon.points.length; i++) {
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dot = polygon.points[i].dot(axis);
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if (dot < res.min) {
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res.min = dot;
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} else if (dot > res.max) {
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res.max = dot;
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}
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}
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return res;
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}
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/**
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* 计算[minA, maxA]和[minB, maxB]之间的距离。如果间隔重叠，距离是负的
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* @param minA
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* @param maxA
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* @param minB
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* @param maxB
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*/
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public static intervalDistance(minA: number, maxA: number, minB: number, maxB: number) {
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if (minA < minB)
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return minB - maxA;
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return minA - maxB;
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}
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}
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} |