Closed
Description
See scratchfoundation/scratch-vm#2291 for more explanation of why this came up, but basically there is an implicit assumption that was introduced when we introduced the hasPremultipliedAlpha flag for skins, that the ghost effect (and possibly other color effects) would not be used on the PenSkin (the only hasPremultipliedAlpha=true skin type). It is implicit because the shader modifies the alpha for ghost in a way that assumes straight alpha composition. There are a number of related issues and proposed solutions, and I don't expect us to have the bandwidth to address them now, but wanted to have a place to track this, given the amount of time invested in understanding scratchfoundation/scratch-vm#2291
Related issues/work
- Ugly dark fringe around resampled costume's edges #459
- Video transparency in video sensing doesn't go all the way invisible scratch-gui#4888
- Consistently use premultiplied alpha throughout the renderer #460
- Fix video transparency and deeply explain the hack scratch-vm#2291
- Shapes have fuzzy black outlines on stage #237