66 lines
2.2 KiB
TypeScript
66 lines
2.2 KiB
TypeScript
class Vector2Ext {
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/**
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* 检查三角形是CCW还是CW
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* @param a
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* @param center
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* @param c
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*/
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public static isTriangleCCW(a: Vector2, center: Vector2, c: Vector2) {
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return this.cross(Vector2.subtract(center, a), Vector2.subtract(c, center)) < 0;
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}
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/**
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* 计算二维伪叉乘点(Perp(u)， v)
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* @param u
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* @param v
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*/
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public static cross(u: Vector2, v: Vector2) {
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return u.y * v.x - u.x * v.y;
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}
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/**
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* 返回与传入向量垂直的向量
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* @param first
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* @param second
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*/
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public static perpendicular(first: Vector2, second: Vector2) {
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return new Vector2(-1 * (second.y - first.y), second.x - first.x);
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}
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/**
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* Vector2的临时解决方案
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* 标准化把向量弄乱了
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* @param vec
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*/
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public static normalize(vec: Vector2) {
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let magnitude = Math.sqrt((vec.x * vec.x) + (vec.y * vec.y));
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if (magnitude > MathHelper.Epsilon) {
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vec = Vector2.divide(vec, new Vector2(magnitude));
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} else {
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vec.x = vec.y = 0;
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}
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return vec;
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}
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public static transformA(sourceArray: Vector2[], sourceIndex: number, matrix: Matrix2D,
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destinationArray: Vector2[], destinationIndex: number, length: number) {
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for (let i = 0; i < length; i ++){
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let position = sourceArray[sourceIndex + i];
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let destination = destinationArray[destinationIndex + i];
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destination.x = (position.x * matrix.m11) + (position.y * matrix.m21) + matrix.m31;
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destination.y = (position.x * matrix.m12) + (position.y * matrix.m22) + matrix.m32;
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destinationArray[destinationIndex + i] = destination;
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}
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}
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public static transformR(position: Vector2, matrix: Matrix2D){
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let x = (position.x * matrix.m11) + (position.y * matrix.m21) + matrix.m31;
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let y = (position.x * matrix.m12) + (position.y * matrix.m22) + matrix.m32;
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return new Vector2(x, y);
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}
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public static transform(sourceArray: Vector2[], matrix: Matrix2D, destinationArray: Vector2[]) {
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this.transformA(sourceArray, 0, matrix, destinationArray, 0, sourceArray.length);
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}
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} |