Displacement output cause unexpected viewport performance issue in EEVEE #97308

New Issue

Zhen Dai · 2022-04-13T13:41:47+02:00

Zhen Dai commented

2022-04-13 13:41:47 +02:00

System Information
Operating system: macOS-12.3-x86_64-i386-64bit 64 Bits
Graphics card: AMD Radeon Pro 580 OpenGL Engine ATI Technologies Inc. 4.1 ATI-4.8.13

Blender Version
Broken: version: 3.1.2, branch: master, commit date: 2022-03-31 17:40, hash: cc66d1020c
Worked: N/A

Short description of error

When displacement output is connected to an image texture node using global position + noise texture to disturb uv (a common anti-tiling pattern), the viewport performance drops significantly, even though EEVEE doesn't support real displacement.

https://streamable.com/vge0jw

Exact steps for others to reproduce the error

Open attached file
Navigate the viewport and notice the lag (see linked video above for reference)
Disable the displacement output link and navigate again, notice the significant speed up.
Re-enable the displacement, but connect geometry input position directly to the image texture node without noise texture, notice the performance is still good.
I have only reproduced it on macOS, don't know if it's platform-dependent.

shader-performance-compressed2.blend

**System Information** Operating system: macOS-12.3-x86_64-i386-64bit 64 Bits Graphics card: AMD Radeon Pro 580 OpenGL Engine ATI Technologies Inc. 4.1 ATI-4.8.13 **Blender Version** Broken: version: 3.1.2, branch: master, commit date: 2022-03-31 17:40, hash: `cc66d1020c` Worked: N/A **Short description of error** When displacement output is connected to an image texture node using global position + noise texture to disturb uv (a common anti-tiling pattern), the viewport performance drops significantly, even though EEVEE doesn't support real displacement. https://streamable.com/vge0jw **Exact steps for others to reproduce the error** - Open attached file - Navigate the viewport and notice the lag (see linked video above for reference) - Disable the displacement output link and navigate again, notice the significant speed up. - Re-enable the displacement, but connect geometry input position directly to the image texture node without noise texture, notice the performance is still good. - I have only reproduced it on macOS, don't know if it's platform-dependent. [shader-performance-compressed2.blend](https://archive.blender.org/developer/F12999864/shader-performance-compressed2.blend)

Zhen Dai commented

2022-04-13 13:41:47 +02:00

Added subscriber: @Zhen-Dai

Germano Cavalcante commented

2022-04-14 19:07:29 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2022-04-14 19:07:29 +02:00

Even though it doesn't support real displacement, Eevee still uses output displacement to calculate normals. It's like the Bump node.
So the compute intensive node "Noise Texture 3D" is still used.
Bump node works at a higher resolution. So it is expected to be 3 or 4 times slower than the color slot.

That said, the combination of "Noise Texture 3D" with nodes that need double the resolution can result in a drop in performance.

Even though it doesn't support real displacement, Eevee still uses output displacement to calculate normals. It's like the Bump node. So the compute intensive node "Noise Texture 3D" is still used. Bump node works at a higher resolution. So it is expected to be 3 or 4 times slower than the color slot. That said, the combination of "Noise Texture 3D" with nodes that need double the resolution can result in a drop in performance.

Germano Cavalcante commented

2022-04-14 19:07:37 +02:00

Closed as duplicate of #79522

Germano Cavalcante closed this issue

2022-04-14 19:07:37 +02:00

Zhen Dai commented

2022-04-15 03:54:54 +02:00

In #97308#1341250, @mano-wii wrote:
Even though it doesn't support real displacement, Eevee still uses output displacement to calculate normals. It's like the Bump node.
So the compute intensive node "Noise Texture 3D" is still used.
Bump node works at a higher resolution. So it is expected to be 3 or 4 times slower than the color slot.

That said, the combination of "Noise Texture 3D" with nodes that need double the resolution can result in a drop in performance.

Thx, I want to double check one thing: is the displacement to normal applied in fragment stage or vertex stage (when we are in bump only mode)?

> In #97308#1341250, @mano-wii wrote: > Even though it doesn't support real displacement, Eevee still uses output displacement to calculate normals. It's like the Bump node. > So the compute intensive node "Noise Texture 3D" is still used. > Bump node works at a higher resolution. So it is expected to be 3 or 4 times slower than the color slot. > > That said, the combination of "Noise Texture 3D" with nodes that need double the resolution can result in a drop in performance. Thx, I want to double check one thing: is the displacement to normal applied in fragment stage or vertex stage (when we are in bump only mode)?

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Displacement output cause unexpected viewport performance issue in EEVEE #97308