In 2.79 this is so simple:
- set the layers for rendering in both objects (camera icon)
- set Bake type to “vertex colors”, “selected to active” and “bake to vertex colors”
- do Bake
Similarly, I can very easily merge multiple vertex colors layers into a single one in 2.79, by doing Bake type: Full Render, while disabling “Textures” in the Render tab.
Neither tasks are possible even in the most recent 2.92 alpha.
I am super excited about having the bake to vertex colors feature back and I am very thankful for that, I am now just little afraid we will have to wait another 3 years to have it back with all the 2.79 features as this is probably something which nobody else uses on a daily basis.
I will try to add the feature request wherever possible, so let’s see.
In this video you can see how the grass blends nicely with the shadows on the ground, this has been done by baking the ground vcols → grass vcols (baking AO to grass directly doesn’t work well due how much low-poly it is, also the ground has some additional color variation (from orthophoto) which is transferred to grass).
EDIT: Also found a bug - baking ignores which layer is set for render and bakes into the selected instead.