Smooth brush is very slow while using MultiRes compared to other brushes #70689

New Issue

Frozen_Death_Knight · 2019-10-10T03:43:32+02:00

2019-10-10 03:43:32 +02:00

System Information
Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: GeForce GTX 980/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.48

Blender Version
Broken: version: 2.81 (sub 14), branch: master, commit date: 2019-10-08 20:10, hash: 6d3c34fe9d
Worked: Used to be faster earlier in the Alpha if I recall, but now it is barely usable even on lower subdivs.

Short description of error
Smoothing your sculpt with MultiRes on is not a very pleasant experience at the moment. Incredibly laggy when compared to all other brushes, especially with the latest patches that vastly improved brush speed and undo while using MultiRes. Since smoothing is such a common action to take while doing any sculpt work, it would be much appreciated if this was taken a look at.

Exact steps for others to reproduce the error
Desktop 2019.10.10 - 03.34.41.01.mp4

**System Information** Operating system: Windows-10-10.0.18362 64 Bits Graphics card: GeForce GTX 980/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.48 **Blender Version** Broken: version: 2.81 (sub 14), branch: master, commit date: 2019-10-08 20:10, hash: `6d3c34fe9d` Worked: Used to be faster earlier in the Alpha if I recall, but now it is barely usable even on lower subdivs. **Short description of error** Smoothing your sculpt with MultiRes on is not a very pleasant experience at the moment. Incredibly laggy when compared to all other brushes, especially with the latest patches that vastly improved brush speed and undo while using MultiRes. Since smoothing is such a common action to take while doing any sculpt work, it would be much appreciated if this was taken a look at. **Exact steps for others to reproduce the error** [Desktop 2019.10.10 - 03.34.41.01.mp4](https://archive.blender.org/developer/F7800321/Desktop_2019.10.10_-_03.34.41.01.mp4)

Frozen_Death_Knight commented

2019-10-10 03:43:32 +02:00

Added subscriber: @Frozen_Death_Knight

Pablo Dobarro commented

2019-10-10 04:01:14 +02:00

Added subscribers: @brecht, @PabloDobarro

Pablo Dobarro commented

2019-10-10 04:01:14 +02:00

I implemented the smooth brush using the sculpt mesh API in P1136 and it is still unusable slow. @brecht Could this be related to the latest multires changes?

I implemented the smooth brush using the sculpt mesh API in [P1136](https://archive.blender.org/developer/P1136.txt) and it is still unusable slow. @brecht Could this be related to the latest multires changes?

Brecht Van Lommel commented

2019-10-10 10:26:45 +02:00

My recent multires changes at least should not have affected smoothing performance, only new tools that did not support multires before. Please compare with 2.80 to check if this is actually a regression.

@PabloDobarro, the multires sculpt API is not particularly fast, there is room for optimization. So I wouldn't necessarily expect it to be faster, it could be slower too. There may be an unknown bottleneck here, use a profiler to figure out which part is actually slow.

multires_stitch_grids() may be part of the problem, it averages coordinates between grids. Since the neighbor iterator does look across grid boundaries averaging of coordinates should ideally not be needed. However smoothing does not make a proper distinction between new and old coordinates, so cracks will still appear.

Doing it once for all iterations may work. I guess ideally this should use old/new coordinates.

In the video strength is 3.0, which means it will do 12 iterations for every brush step, which is also just fundamentally a lot of work.

My recent multires changes at least should not have affected smoothing performance, only new tools that did not support multires before. Please compare with 2.80 to check if this is actually a regression. @PabloDobarro, the multires sculpt API is not particularly fast, there is room for optimization. So I wouldn't necessarily expect it to be faster, it could be slower too. There may be an unknown bottleneck here, use a profiler to figure out which part is actually slow. `multires_stitch_grids()` may be part of the problem, it averages coordinates between grids. Since the neighbor iterator does look across grid boundaries averaging of coordinates should ideally not be needed. However smoothing does not make a proper distinction between new and old coordinates, so cracks will still appear. Doing it once for all iterations may work. I guess ideally this should use old/new coordinates. In the video strength is 3.0, which means it will do 12 iterations for every brush step, which is also just fundamentally a lot of work.

Frozen_Death_Knight commented

2019-10-10 13:13:24 +02:00

@brecht I can assure you, having the setting at 1.000 does not make a difference on my machine (I get a buttery smooth smoothing at 3.000 on non-MultiRes meshes at far higher polygon numbers than this). It is only around 0.600-0.700 when the brush behaves at acceptable levels of lag.

Desktop 2019.10.10 - 13.09.04.01.mp4

@brecht I can assure you, having the setting at 1.000 does not make a difference on my machine (I get a buttery smooth smoothing at 3.000 on non-MultiRes meshes at far higher polygon numbers than this). It is only around 0.600-0.700 when the brush behaves at acceptable levels of lag. [Desktop 2019.10.10 - 13.09.04.01.mp4](https://archive.blender.org/developer/F7801323/Desktop_2019.10.10_-_13.09.04.01.mp4)

Vertex commented

2019-10-10 21:10:58 +02:00

Added subscriber: @VertexPainter

Pablo Dobarro commented

2019-10-11 00:00:14 +02:00

This is a regression from 2.79, but it is also slower than in 2.80.
2.79 -> 2.80 -> 2.81 (with TBB)
2019-10-11 00-00-32.mp4

This is a regression from 2.79, but it is also slower than in 2.80. 2.79 -> 2.80 -> 2.81 (with TBB) [2019-10-11 00-00-32.mp4](https://archive.blender.org/developer/F7803494/2019-10-11_00-00-32.mp4)

Petter Lundh commented

2019-10-29 16:26:06 +01:00

Added subscriber: @PetterLundh