Driving object scale also scales its particle instances. #87413

New Issue

Erich Brutus · 2021-04-12T10:06:04+02:00

Erich Brutus commented

2021-04-12 10:06:04 +02:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.92

Blender Version
Broken: version: 2.92.0, branch: master, commit date: 2021-02-24 16:25, hash: 02948a2cab
Worked: (newest version of Blender that worked as expected)

Short description of error
When scaling the object that the particles are on, everything works correctly, the particles stay at the same size they are supposed to.

But when driving the exact same scale variable with a driver, for some reason the particles get scaled.
The property has to be on another object than the particle system, when it's on the object with particle system, then everything works as expected.

Exact steps for others to reproduce the error

Open attached file
Change the 'prop' value (particle instances also get scaled)
Now select the object with the particles
Disable the driver
Scale in x direction (particles stay at the same size they are supposed to)

Pressing "Update Dependencies" fixes the scale, but in my real project that is unfeasible thing to do, I have many parameters that are driven that need to be animated and clicking them all through each time I make a tiny change is not possible. Also, rendering does not always fix the scales either.

DriverPartBug.blend

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.92 **Blender Version** Broken: version: 2.92.0, branch: master, commit date: 2021-02-24 16:25, hash: `02948a2cab` Worked: (newest version of Blender that worked as expected) **Short description of error** When scaling the object that the particles are on, everything works correctly, the particles stay at the same size they are supposed to. ![m2.jpg](https://archive.blender.org/developer/F9930230/m2.jpg) But when driving the exact same scale variable with a driver, for some reason the particles get scaled. The property has to be on another object than the particle system, when it's on the object with particle system, then everything works as expected. ![m0.JPG](https://archive.blender.org/developer/F9930217/m0.JPG) ![m1.JPG](https://archive.blender.org/developer/F9930219/m1.JPG) **Exact steps for others to reproduce the error** - Open attached file - Change the 'prop' value (particle instances also get scaled) - Now select the object with the particles - Disable the driver - Scale in x direction (particles stay at the same size they are supposed to) Pressing "Update Dependencies" fixes the scale, but in my real project that is unfeasible thing to do, I have many parameters that are driven that need to be animated and clicking them all through each time I make a tiny change is not possible. Also, rendering does not always fix the scales either. [DriverPartBug.blend](https://archive.blender.org/developer/F9930223/DriverPartBug.blend)

Erich Brutus commented

2021-04-12 10:06:04 +02:00

Added subscriber: @ErichBrutus

Germano Cavalcante commented

2021-04-14 23:05:39 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2021-04-14 23:05:39 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Germano Cavalcante commented

2021-04-14 23:05:39 +02:00

This comment was removed by @mano-wii

*This comment was removed by @mano-wii*

Germano Cavalcante changed title from ~~Driving particle distribute object scale also scales particles.~~ to Driving object scale also scales its particle instances.

2021-04-23 16:13:16 +02:00

Sybren A. Stüvel commented

2022-11-15 17:26:44 +01:00

Added subscriber: @dr.sybren

Sybren A. Stüvel commented

2022-11-15 17:26:44 +01:00

Since this is an issue with the deprecated particle system, we won't fix this issue.

In short, it is unclear what fixing this will bring. It is likely that the driver is actually doing the correct thing: scaling particles along with the object they're attached to, in the same way that they rotate and translate along with that object. This would mean that fixing this issue would very likely break people's files (because scaling the object will all of a sudden have an effect on the particle scale).

Instead of the particle system, use Geometry Nodes to scatter objects. This is a modern system that's flexible, powerful, and under active development.

Since this is an issue with the deprecated particle system, we won't fix this issue. In short, it is unclear what fixing this will bring. It is likely that the driver is actually doing the correct thing: scaling particles along with the object they're attached to, in the same way that they rotate and translate along with that object. This would mean that fixing this issue would very likely break people's files (because scaling the object will all of a sudden have an effect on the particle scale). Instead of the particle system, use Geometry Nodes to scatter objects. This is a modern system that's flexible, powerful, and under active development.

Philipp Oeser removed the

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Driving object scale also scales its particle instances. #87413