02-09-2020, 09:48 PM
I'm glad you found the cause so quickly!
In Tilengine you must specify a base background: either a solid color with TLN_SetBGColor() or a fixed bitmap with TLN_SetBGBitmap(). If not, pixels that are not covered by any background layer aren't cleared between frames, leaving the trace you see in the picture. This is not a bug, it's by design, to avoid unnecesary overdraw when you use a background layer that you know that it hasn't transparent pixels, so a base background is not needed.
This is unrelated to raster effects.
In Tilengine you must specify a base background: either a solid color with TLN_SetBGColor() or a fixed bitmap with TLN_SetBGBitmap(). If not, pixels that are not covered by any background layer aren't cleared between frames, leaving the trace you see in the picture. This is not a bug, it's by design, to avoid unnecesary overdraw when you use a background layer that you know that it hasn't transparent pixels, so a base background is not needed.
This is unrelated to raster effects.