Use pivots yet again

Engine/src/shared/sprites.ts

@@ -55,11 +55,15 @@ export class SpriteInstance {
       this.frameCount = this.subset.frames.length
       this.frame = this.subset.frames[this.frameIndex]
       let s = new PIXI.Sprite(this.frame.texture)
-      if (this.frame.originX) {
+      if (this.frame.originX !== undefined) {
         s.pivot.x = this.frame.originX
+      } else {
+        s.pivot.x = s.width / 2
       }
-      if (this.frame.originY) {
+      if (this.frame.originY !== undefined) {
         s.pivot.y = this.frame.originY
+      } else {
+        s.pivot.y = s.height / 2
       }
       this.container.addChild(s)
     }
@@ -85,4 +89,17 @@ export class SpriteInstance {
     }
     return
   }
+
+  get width(): number {
+    return this.frame?.width ?? this.container.width
+  }
+  get height(): number {
+    return this.frame?.height ?? this.container.height
+  }
+  get originY(): number {
+    return this.frame?.originY ?? 0
+  }
+  get originX(): number {
+    return this.frame?.originX ?? 0
+  }
 }