Descriptive Problem Summary:
When targeting a render_source with an alpha mask that's the product of a plane_master, I'm getting strange positioning results of the resultant alpha mask. This also seems to affect composite filters. The expected behavior is that the slate will appear on screen in the same position as it would have rendered as a part of the master plane. The outcome though, is that the slate is being cropped to the extent of the render area, and then positioned at the top-left of the screen when used on a non-plane master screen object, which is really, really strange behavior.
A test case for this was prepared in BYONDiscord, but as it uses art assets from another developer I was debugging this issue for, and designing a vfx render stack for, I will not forward it here.
Sep 15, 9:51 pm