GNOME Bugzilla – Bug 779778
Merge down into transparent space destroys upper layer content when any blend mode is used
Last modified: 2017-06-13 16:55:39 UTC
When merging down any top layer with a blend mode into empty transparent space in the layer below, the top layer content doesn't get blended down and merged. It just disappears. Gimp seems to check if there is content below the top layer, and if there isn't (even if there is a lower layer providing background for the blend mode), the content is not merged correctly. If any of the top layer content overlaps with content in the bottom layer, the top layer merges with the bottom layer as it appears before merging. Repro 1. create three layers in a new document: - non transparent background layer filled with anything - transparent layer (middle) with some content eg brush squiggle - second transparent layer (top) with some content, eg brush squiggle (some of which overlaps the middle layer content) 2. set top layer blend mode to whatever, eg hard light. Can see that the hard light effect is working, the top layer content is blended differently where it overlaps the middle layer, and the background. 3. Merge down top layer into the middle transparent layer. 4. See that the content that got merged down into empty transparent canvas was lost, but where it overlapped, it was correctly blended with the middle layer. Expected outcome: The top layer content is never lost. When merging down, Gimp takes the visible content (much like how 'copy visible' works) from that layer at the time of merging (eg, in this example, the part blended with the background layer), and brings it to the lower layer. I believe I am correct in saying this was the behaviour in the past, because this strikes me as extremely bizarre and different behaviour (I just installed new Gimp on a new PC, my previous version was a few years old). I am certain I have had multiple stacked transparency layers, and have merged down okay in the past. This is kind of crippling and hard to work around when doing texture editing.
Addition: I actually ran into this issue whilst having two layers with the same blend mode, aligned side-by-side, both blending with the layer immediately below them. I wanted to merge the top layer down to have a single layer to work on, since they were both using hard light blend, I would expect that to work okay. Instead, the top layer just disappears when merging. As it is, my only resolution is to manually copy the content from the top layer into the bottom layer, expanding the layer first to fit.. which seems overly tedious, and I'm sure I never had to do this before.
Make all layers below the merged-to layer invisible, it will look exactly the same. Merging down merges down *only* to the layer exactly below. If there are blend modes other than normal involved, it is simply impossible to look the same as before.