Adding a Scene Line Art Grease Pencil object is 20X slower in 3.0 vs 2.93 #90695

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Chipp Walters · 2021-08-16T03:14:17+02:00

Chipp Walters commented

2021-08-16 03:14:17 +02:00

System Information
Operating system: Win 10
Graphics card: RTX 3900
Processor 11th Gen Intel(R) Core(TM) i9-11900KF @ 3.50GHz, 3504 Mhz, 8 Core(s), 16 Logical Processor(s)
Installed Physical Memory (RAM) 64.0 GB

Blender Version
Broken: 3.0.0 Alpha Date: 2021-08-14 Hash: d 5 2 6 1 e 9 7 3 b 5 6 Branch: master
Worked: 2.93.0 Date: 2021-06-02 Hash: 84da05a8b06

Short description of error
Adding a Scene Line Art Grease Pencil object is 20X slower in 3.0 vs 2.93

Exact steps for others to reproduce the error
Did the same for both versions of Blender:

Opened attached scene file (simplified but has a many faces)
Shift-A > Grease Pencil > Scene Line Art
Waited for the Line Art to be rendered.

In 2.93 on my (fast) system it rendered in 17 seconds
In the latest master release of 3.0, it renders in 5 min 32 seconds

Note: edited this report to compress the file and change the name of the file.

blender-line-art-bug.blend

**System Information** Operating system: Win 10 Graphics card: RTX 3900 Processor 11th Gen Intel(R) Core(TM) i9-11900KF @ 3.50GHz, 3504 Mhz, 8 Core(s), 16 Logical Processor(s) Installed Physical Memory (RAM) 64.0 GB **Blender Version** Broken: 3.0.0 Alpha Date: 2021-08-14 Hash: d 5 2 6 1 e 9 7 3 b 5 6 Branch: master Worked: 2.93.0 Date: 2021-06-02 Hash: 84da05a8b06 **Short description of error** Adding a Scene Line Art Grease Pencil object is 20X slower in 3.0 vs 2.93 **Exact steps for others to reproduce the error** Did the same for both versions of Blender: 1. Opened attached scene file (simplified but has a many faces) 2. Shift-A > Grease Pencil > Scene Line Art 3. Waited for the Line Art to be rendered. In 2.93 on my (fast) system it rendered in 17 seconds In the latest master release of 3.0, it renders in 5 min 32 seconds Note: edited this report to compress the file and change the name of the file. [blender-line-art-bug.blend](https://archive.blender.org/developer/F10283455/blender-line-art-bug.blend)

Chipp Walters commented

2021-08-16 03:14:17 +02:00

Added subscriber: @chippwalters

Antonio Vazquez commented

2021-08-16 12:09:58 +02:00

Added subscribers: @ChengduLittleA, @antoniov

Antonio Vazquez commented

2021-08-16 12:09:58 +02:00

@ChengduLittleA Could you take a look?

YimingWu commented

2021-08-17 05:46:48 +02:00

sure... let me check.

YimingWu commented

2021-08-17 10:29:05 +02:00

After a fix, now runs fine now somewhere near 25s on my surface, should be close to your 2.93 performance on your machine. I'll attach a patch here shortly.

Note that in the model there are some hugely unnecessarily dense structures in some portions of the image. This will slow down line art no matter what algorithm it chooses. I modified a value there in line art so it has better tolerance to this kind of situations (close to 2.93's), but because line art does not work by ray tracing, so once there are hundreds and thousands of triangles piling up in the exact same position in the image, it's not gonna work that well. As a general rule, models (especially mechanical ones) doesn't need triangles to be this dense.

A more optimized algorithm is been developed right now, so hopefully this problem can be better handled in upcoming releases. So this fix is more like a temporary thing where we make line art still usable for such mesh structures before "real" 3.0 release.

![图片.png](https://archive.blender.org/developer/F10285853/图片.png) After a fix, now runs fine now somewhere near 25s on my surface, should be close to your 2.93 performance on your machine. I'll attach a patch here shortly. ![图片.png](https://archive.blender.org/developer/F10285856/图片.png) Note that in the model there are some hugely unnecessarily dense structures in some portions of the image. This will slow down line art no matter what algorithm it chooses. I modified a value there in line art so it has better tolerance to this kind of situations (close to 2.93's), but because line art does not work by ray tracing, so once there are hundreds and thousands of triangles piling up in the exact same position in the image, it's not gonna work that well. As a general rule, models (especially mechanical ones) doesn't need triangles to be this dense. A more optimized algorithm is been developed right now, so hopefully this problem can be better handled in upcoming releases. So this fix is more like a temporary thing where we make line art still usable for such mesh structures before "real" 3.0 release.

Chipp Walters commented

2021-08-17 11:42:25 +02:00

Thanks for the fix, Yiming. I know about the density issue and the time required to create the different LINE ART objects. I was just pointing out the huge discrepancy in calculation time between the two versions.

blender-admin commented

2021-08-18 06:02:32 +02:00

This issue was referenced by f41beca977

This issue was referenced by f41beca97787d017a437a63cc0da2ce991522dea

YimingWu commented

2021-08-18 06:47:33 +02:00

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

YimingWu closed this issue

2021-08-18 06:47:33 +02:00

YimingWu self-assigned this 2021-08-18 06:47:33 +02:00

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Adding a Scene Line Art Grease Pencil object is 20X slower in 3.0 vs 2.93 #90695