feat: initialize mini program map engine

miniprogram/engine/camera/camera.ts

@@ -0,0 +1,98 @@
+export interface CameraState {
+  centerWorldX: number
+  centerWorldY: number
+  viewportWidth: number
+  viewportHeight: number
+  visibleColumns: number
+  translateX?: number
+  translateY?: number
+  rotationRad?: number
+}
+
+export interface ScreenPoint {
+  x: number
+  y: number
+}
+
+export interface WorldPoint {
+  x: number
+  y: number
+}
+
+export function getTileSizePx(camera: CameraState): number {
+  if (!camera.viewportWidth || !camera.visibleColumns) {
+    return 0
+  }
+
+  return camera.viewportWidth / camera.visibleColumns
+}
+
+export function rotateScreenPoint(point: ScreenPoint, centerX: number, centerY: number, rotationRad: number): ScreenPoint {
+  if (!rotationRad) {
+    return point
+  }
+
+  const deltaX = point.x - centerX
+  const deltaY = point.y - centerY
+  const cos = Math.cos(rotationRad)
+  const sin = Math.sin(rotationRad)
+
+  return {
+    x: centerX + deltaX * cos - deltaY * sin,
+    y: centerY + deltaX * sin + deltaY * cos,
+  }
+}
+
+export function worldToScreen(
+  camera: CameraState,
+  world: WorldPoint,
+  includeTranslate = false,
+): ScreenPoint {
+  const tileSize = getTileSizePx(camera)
+  const translateX = includeTranslate ? (camera.translateX || 0) : 0
+  const translateY = includeTranslate ? (camera.translateY || 0) : 0
+  const centerX = camera.viewportWidth / 2
+  const centerY = camera.viewportHeight / 2
+
+  const rotated = rotateScreenPoint(
+    {
+      x: centerX + (world.x - camera.centerWorldX) * tileSize,
+      y: centerY + (world.y - camera.centerWorldY) * tileSize,
+    },
+    centerX,
+    centerY,
+    camera.rotationRad || 0,
+  )
+
+  return {
+    x: rotated.x + translateX,
+    y: rotated.y + translateY,
+  }
+}
+
+export function screenToWorld(
+  camera: CameraState,
+  screen: ScreenPoint,
+  includeTranslate = true,
+): WorldPoint {
+  const tileSize = getTileSizePx(camera)
+  const translateX = includeTranslate ? (camera.translateX || 0) : 0
+  const translateY = includeTranslate ? (camera.translateY || 0) : 0
+  const centerX = camera.viewportWidth / 2
+  const centerY = camera.viewportHeight / 2
+
+  const unrotated = rotateScreenPoint(
+    {
+      x: screen.x - translateX,
+      y: screen.y - translateY,
+    },
+    centerX,
+    centerY,
+    -(camera.rotationRad || 0),
+  )
+
+  return {
+    x: camera.centerWorldX + (unrotated.x - centerX) / tileSize,
+    y: camera.centerWorldY + (unrotated.y - centerY) / tileSize,
+  }
+}