Clustered Light Culing #68474

New Issue

Clément Foucault · 2019-08-09T16:57:36+02:00

Clément Foucault commented

2019-08-09 16:57:36 +02:00

Lights evaluation is what takes the most time in eevee. Using Clustered light culling, we could cut down the evaluation time by evaluating only lights present in the view.

This needs further investigation as how to communicate what lights are visible. Light Bits is the most straight forward way but it severly limits the number of lights per froxel.
Also findMSB (glsl bitscan) is GL 4.0 only, so need to review other alternative. (avalanche studio slides link).

We need a way to cull thoses on GPU (pixel shader per froxel?) for efficiency.
Need more investigation about the state of the art techniques.
Issue is that it takes another texture slot. Could we use a UBO instead and use bigger froxel? (Can't write to UBO using shaders)

Estimate : 2 weeks

Lights evaluation is what takes the most time in eevee. Using Clustered light culling, we could cut down the evaluation time by evaluating only lights present in the view. This needs further investigation as how to communicate what lights are visible. Light Bits is the most straight forward way but it severly limits the number of lights per froxel. Also findMSB (glsl bitscan) is GL 4.0 only, so need to review other alternative. (avalanche studio slides [link](http://www.humus.name/Articles/PracticalClusteredShading.pdf)). We need a way to cull thoses on GPU (pixel shader per froxel?) for efficiency. Need more investigation about the state of the art techniques. Issue is that it takes another texture slot. Could we use a UBO instead and use bigger froxel? (Can't write to UBO using shaders) Estimate : 2 weeks

Clément Foucault commented

2019-08-09 16:57:36 +02:00

Added subscriber: @fclem

zebus3d commented

2019-08-10 01:13:50 +02:00

Added subscriber: @zebus3dream

Maximilian Krüger commented

2019-08-12 17:46:19 +02:00

Added subscriber: @SomaZ

Maximilian Krüger commented

2019-08-12 17:46:19 +02:00

There's an alternative to clustered shading called BVH Accelerated Shading. Downside, you need to maintain a bvh on the cpu side, upside, you don't need any compute shaders and you aren't limted to a fixed count of lights.
Maybe worth looking into it: Simple Alternative to Clustered Shading for Thousands of Lights

There's an alternative to clustered shading called BVH Accelerated Shading. Downside, you need to maintain a bvh on the cpu side, upside, you don't need any compute shaders and you aren't limted to a fixed count of lights. Maybe worth looking into it: [Simple Alternative to Clustered Shading for Thousands of Lights ](https://worldoffries.wordpress.com/2015/02/19/simple-alternative-to-clustered-shading-for-thousands-of-lights/)

Laurent Noel commented

2019-10-18 00:22:52 +02:00

Added subscriber: @c2ba

Julien Leménicier commented

2019-10-22 16:41:42 +02:00

Added subscriber: @lemenicier_julien

Amad Muhammad commented

2020-02-15 17:11:10 +01:00

Added subscriber: @Nakara

AnityEx commented

2020-04-01 18:25:46 +02:00

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Kenzie commented

2020-08-25 11:51:51 +02:00

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Emi Martinez commented

2021-04-06 02:39:36 +02:00

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Donovane commented

2021-10-15 22:51:34 +02:00

Added subscriber: @dodo-2

Donovane commented

2021-10-15 22:52:17 +02:00

Any update for this task ?

Clément Foucault commented

2021-10-16 09:29:28 +02:00

I went for 2.5D light culling. It is already inside eevee-rewrite.

I went for 2.5D light culling. It is already inside `eevee-rewrite`.

Donovane commented

2021-10-16 10:03:48 +02:00

In #68474#1236655, @fclem wrote:
I went for 2.5D light culling. It is already inside eevee-rewrite.

Ok nice 😊

> In #68474#1236655, @fclem wrote: > I went for 2.5D light culling. It is already inside `eevee-rewrite`. Ok nice 😊

Basil commented

2021-10-20 00:31:57 +02:00

Added subscriber: @Defka

Donovane commented

2021-10-26 01:03:08 +02:00

@fclem I have build the EEVEE-REWRITE BRANCH, also i have tested the Simplify > Culling > Cam and Distance Cull, both doesn't work.
idk if the work is finish or just stated, but you can view my review here : https://developer.blender.org/T92482

Same thing in my post : I know is a branch and the job isn't finished ^^

I has read the desc but idk if is updated or no...if is i know why he doesn't work x')

Thank's :)

@fclem I have build the EEVEE-REWRITE BRANCH, also i have tested the Simplify > Culling > Cam and Distance Cull, both doesn't work. idk if the work is finish or just stated, but you can view my review here : https://developer.blender.org/T92482 Same thing in my post : I know is a branch and the job isn't finished ^^ I has read the desc but idk if is updated or no...if is i know why he doesn't work x') Thank's :)

Clément Foucault commented

2021-10-26 09:43:23 +02:00

@dodo-2 you misunderstood the feature. The light culling discussed here is not about the options under the Simplify tab which are specific to Cycles. I believe they are not working because my branch is quite outdated compared to master.

The light culling of this task is about an internal feature that speed up the rendering when there is a high number of light in the scene. There is no parameter in the UI since the feature is always enabled.

@dodo-2 you misunderstood the feature. The light culling discussed here is not about the options under the `Simplify` tab which are specific to Cycles. I believe they are not working because my branch is quite outdated compared to master. The light culling of this task is about an internal feature that speed up the rendering when there is a high number of light in the scene. There is no parameter in the UI since the feature is always enabled.

Donovane commented

2021-10-26 21:10:01 +02:00

@fclem Oh okay my bad ^^' But at least you know that camera culling doesn't work x')

Philipp Oeser removed the

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Clustered Light Culing #68474