146 lines
4.9 KiB
TypeScript
146 lines
4.9 KiB
TypeScript
import { EntitySystem, Matcher, Entity, ECSSystem, HierarchyComponent } from '@esengine/ecs-framework';
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import { TransformComponent, Matrix2D } from './TransformComponent';
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const DEG_TO_RAD = Math.PI / 180;
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/**
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* 变换系统
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* Transform System - Calculates world transforms based on hierarchy
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*
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* 根据实体层级关系计算世界变换矩阵。
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* 子实体的世界变换 = 父实体世界变换 * 子实体本地变换
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*/
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@ECSSystem('Transform', { updateOrder: -100 })
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export class TransformSystem extends EntitySystem {
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constructor() {
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super(Matcher.empty().all(TransformComponent));
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}
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protected override process(entities: readonly Entity[]): void {
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// 获取所有根实体（没有父级或父级没有 TransformComponent）
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const rootEntities = entities.filter(e => {
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const hierarchy = e.getComponent(HierarchyComponent);
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if (!hierarchy || hierarchy.parentId === null) {
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return true;
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}
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const parent = this.scene?.findEntityById(hierarchy.parentId);
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return !parent || !parent.hasComponent(TransformComponent);
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});
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// 从根实体开始递归计算世界变换
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for (const entity of rootEntities) {
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this.updateWorldTransform(entity, null);
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}
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}
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/**
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* 递归更新实体及其子实体的世界变换
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*/
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private updateWorldTransform(entity: Entity, parentMatrix: Matrix2D | null): void {
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const transform = entity.getComponent(TransformComponent);
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if (!transform) return;
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// 计算本地变换矩阵
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const localMatrix = this.calculateLocalMatrix(transform);
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// 计算世界变换矩阵
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if (parentMatrix) {
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// 世界矩阵 = 父矩阵 * 本地矩阵
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transform.localToWorldMatrix = this.multiplyMatrices(parentMatrix, localMatrix);
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} else {
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// 没有父级，本地矩阵就是世界矩阵
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transform.localToWorldMatrix = localMatrix;
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}
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// 从世界矩阵提取世界位置、旋转、缩放
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this.decomposeMatrix(transform);
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transform.bDirty = false;
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// 递归处理子实体
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const hierarchy = entity.getComponent(HierarchyComponent);
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if (hierarchy && hierarchy.childIds.length > 0) {
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for (const childId of hierarchy.childIds) {
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const child = this.scene?.findEntityById(childId);
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if (child) {
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this.updateWorldTransform(child, transform.localToWorldMatrix);
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}
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}
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}
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}
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/**
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* 计算本地变换矩阵
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*/
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private calculateLocalMatrix(transform: TransformComponent): Matrix2D {
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const { position, rotation, scale } = transform;
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// 只使用 z 轴旋转（2D）
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const rad = rotation.z * DEG_TO_RAD;
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const cos = Math.cos(rad);
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const sin = Math.sin(rad);
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// 构建仿射变换矩阵: Scale -> Rotate -> Translate
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// [a c tx] [sx 0 0] [cos -sin 0] [1 0 tx]
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// [b d ty] = [0 sy 0] * [sin cos 0] * [0 1 ty]
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// [0 0 1] [0 0 1] [0 0 1] [0 0 1]
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return {
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a: scale.x * cos,
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b: scale.x * sin,
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c: scale.y * -sin,
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d: scale.y * cos,
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tx: position.x,
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ty: position.y
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};
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}
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/**
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* 矩阵乘法: result = a * b
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*/
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private multiplyMatrices(a: Matrix2D, b: Matrix2D): Matrix2D {
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return {
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a: a.a * b.a + a.c * b.b,
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b: a.b * b.a + a.d * b.b,
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c: a.a * b.c + a.c * b.d,
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d: a.b * b.c + a.d * b.d,
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tx: a.a * b.tx + a.c * b.ty + a.tx,
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ty: a.b * b.tx + a.d * b.ty + a.ty
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};
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}
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/**
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* 从世界矩阵分解出位置、旋转、缩放
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*/
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private decomposeMatrix(transform: TransformComponent): void {
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const m = transform.localToWorldMatrix;
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// 位置直接从矩阵获取
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transform.worldPosition.x = m.tx;
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transform.worldPosition.y = m.ty;
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transform.worldPosition.z = transform.position.z;
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// 计算缩放
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const scaleX = Math.sqrt(m.a * m.a + m.b * m.b);
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const scaleY = Math.sqrt(m.c * m.c + m.d * m.d);
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// 检测负缩放（通过行列式符号）
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const det = m.a * m.d - m.b * m.c;
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const sign = det < 0 ? -1 : 1;
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transform.worldScale.x = scaleX;
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transform.worldScale.y = scaleY * sign;
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transform.worldScale.z = transform.scale.z;
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// 计算旋转（从归一化的矩阵）
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if (scaleX > 1e-10) {
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const rotation = Math.atan2(m.b / scaleX, m.a / scaleX);
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transform.worldRotation.z = rotation / DEG_TO_RAD;
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} else {
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transform.worldRotation.z = 0;
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}
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transform.worldRotation.x = transform.rotation.x;
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transform.worldRotation.y = transform.rotation.y;
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}
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}
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