Creating new texture slot of particle systems by python will corrupt texture's influence on particles. #77985

New Issue

Borek Bures · 2020-06-18T04:21:06+02:00

Borek Bures commented

2020-06-18 04:21:06 +02:00

System Information
Operating system: Win
Graphics card:

Blender Version
Broken: 2.83.0 LTS (2.90.0 Alpha Hash: b89898cbd3)
Worked: never

Short description of error
Creating new texture slot of particle systems by python will corrupt texture's influence on particles.

Exact steps for others to reproduce the error

open TextureSlot_Bug.blend
run script: SetTextureSlot_bug.py
select Plane object and execute operator: setparticlestextureslot
- script will create new particles texture slot
- appends black/white texture to the created slot
- sets influence of density
then particles should be masked only on half of plane, but they are not - slot is corrupted

Workaround - bug proof

reopen TextureSlot_Bug.blend
select Plane object particles and create new empty texture on first Texture slot
remove this texture - this step will create new empty slot
run script: SetTextureSlot_bug.py and execute operator: setparticlestextureslot
the particles are masked - everything works properly because script doesn't have to create a new texture slot
TextureSlot_Bug.blend

**System Information** Operating system: Win Graphics card: **Blender Version** Broken: 2.83.0 LTS (2.90.0 Alpha Hash: b89898cbd381) Worked: never **Short description of error** Creating new texture slot of particle systems by python will corrupt texture's influence on particles. **Exact steps for others to reproduce the error** 1. open TextureSlot_Bug.blend 2. run script: SetTextureSlot_bug.py 3. select Plane object and execute operator: setparticlestextureslot - script will create new particles texture slot - appends black/white texture to the created slot - sets influence of density 4. then particles should be masked only on half of plane, but they are not - slot is corrupted Workaround - bug proof 1. reopen TextureSlot_Bug.blend 2. select Plane object particles and create new empty texture on first Texture slot 3. remove this texture - this step will create new empty slot 4. run script: SetTextureSlot_bug.py and execute operator: setparticlestextureslot 5. the particles are masked - everything works properly because script doesn't have to create a new texture slot [TextureSlot_Bug.blend](https://archive.blender.org/developer/F8629360/TextureSlot_Bug.blend)

Borek Bures commented

2020-06-18 04:21:06 +02:00

Added subscriber: @BorekBures

Philipp Oeser commented

2020-06-22 10:53:09 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2020-06-22 10:53:09 +02:00

This is due to the texture slot being created with 'MIX' blend_type from the API by default (whereas if you do the same from the interface, it is created with 'MULTIPLY')

So workaround is to set the
mtex.blend_type = 'MULTIPLY'
in your script, see:
TextureSlot_Bug_corrected.blend

This has been reported before, see #76951 (Particle system texture added via API not working ['blend_type' when created using the interface is MULTIPLY, whereas when created through API, its value is MIX]), will merge these reports...

This is due to the texture slot being created with 'MIX' `blend_type` from the API by default (whereas if you do the same from the interface, it is created with 'MULTIPLY') So workaround is to set the `mtex.blend_type = 'MULTIPLY'` in your script, see: [TextureSlot_Bug_corrected.blend](https://archive.blender.org/developer/F8636516/TextureSlot_Bug_corrected.blend) This has been reported before, see #76951 (Particle system texture added via API not working ['blend_type' when created using the interface is MULTIPLY, whereas when created through API, its value is MIX]), will merge these reports...

Philipp Oeser commented

2020-06-22 10:53:22 +02:00

Closed as duplicate of #76951

Philipp Oeser closed this issue

2020-06-22 10:53:22 +02:00

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Creating new texture slot of particle systems by python will corrupt texture's influence on particles. #77985