added GrabbableCamera

source/funkin/graphics/framebuffer/BitmapDataTools.hx

@@ -0,0 +1,43 @@
+package funkin.graphics.framebuffer;
+
+import flixel.FlxG;
+import openfl.display.Bitmap;
+import openfl.display.BitmapData;
+import openfl.display.Sprite;
+import openfl.filters.BitmapFilter;
+
+/**
+ * Provides cool stuff for `BitmapData`s that have a hardware texture internally.
+ */
+class BitmapDataTools
+{
+  /**
+   * Applies a bitmap filter to a bitmap immediately. The bitmap filter may refer
+   * the bitmap itself as a shader input.
+   * @param bitmap the bitmap data
+   * @param filter the bitmap filter
+   */
+  public static function applyFilter(bitmap:BitmapData, filter:BitmapFilter):Void
+  {
+    if (bitmap.readable)
+    {
+      FlxG.log.error('do not use `BitmapDataTools` for non-GPU bitmaps!');
+    }
+    // man, allow me to use anon structuers for local vars!
+    static var cache:{sprite:Sprite, bitmap:Bitmap} = null;
+    if (cache == null)
+    {
+      final sprite = new Sprite();
+      final bitmap = new Bitmap();
+      sprite.addChild(bitmap);
+      cache =
+        {
+          sprite: sprite,
+          bitmap: bitmap
+        }
+    }
+    cache.bitmap.bitmapData = bitmap;
+    cache.sprite.filters = [filter];
+    bitmap.draw(cache.sprite);
+  }
+}