Hello! Sorry for the Google Translate ....
I tried to port the filters on the engine Yogurt3D Away3D. Almost happened. Faced with only one unknown to me the moment:
What makes Away3D texture that it behaves?

It feels as if the texture is rendered in a scene that just cropped.
Textures of both engines in the same scene are rendered. What’s in the top, in the lower example. (1024 x 512)
But Away3D behaves as it is necessary only if the size of the viewport are also equal to 1024x512.
What those who have thought about this? How can this be fixed a?
Thank you all in advance.

All right. I found a place from which it depends ...

RTTBufferManager.as

public function set viewWidth(value : int) : void
{
    if (value == _viewWidth) return;
    _viewWidth = value;

    _buffersInvalid = true;

    _textureWidth = TextureUtils.getBestPowerOf2(_viewWidth);
    if (_textureWidth > _viewWidth) _textureWidth >>= 1; //fix
 
    if (_textureWidth > _viewWidth) {
      _renderToTextureRect.x = uint((_textureWidth-_viewWidth)*.5);
      _renderToTextureRect.width = _viewWidth;
    } else {
      _renderToTextureRect.x = 0;
      _renderToTextureRect.height = _textureHeight;
    }

  dispatchEvent(new Event(Event.RESIZE));
}

Maybe there is a better solution? Suggestions?

Have you any idea?