Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71
Broken: version: 2.90.1, branch: master, commit date: 2020-09-23 06:43, hash: rB3e85bb34d0d7
Short description of error
When using DataTransfer modifier to transfer vertex colors from object to another, vertex color alpha interferes with color transfer. Vertex color alpha seems to work as a mask which is not expected.
Exact steps for others to reproduce the error(See attached blend file for ready-made setup)
- Create a cube. Give it a vertex color layer.
- Create another cube or plane. Give it fully red, blue or green coloring and erase some parts of its vertex color alpha.
- Add Data transfer modifier to the first cube. Copy vertex colors from the other object. Only 'Above' and 'Below threshold' Mix mode settings seems to fully transfer RGB without alpha affecting the transfer.
- Create material for the cube that has copied values. Create emissive shader and attach vertex color input node into it.
- Check with different mix modes and see how result varies.
- Optionally: Apply data transfer and inspect vertex colors. Alpha causes issue with RGB channels.