Cluster forward/deferred rendering?

[swq0553]

Has anyone tried to implement a “Cluster forward/deferred rendering” renderpath？

[JSandusky]

Yes. It wasn't pleasant and required implementing even more primitive compute than I submitted to RBFX. I Gave Clustered, Spherical-Coordinate cells, and Sphere-tree BVH the run. I've stuck to Sphere-tree BVH as I moved to a pulling pipeline.

Atlasing shadowmaps is where most attempts will fail as the shader changes for those aren't really obvious.

You can classify analytic lights via:

bool Light::IsAnalytic() const
{
    if (auto renderer = GetSubsystem<Renderer>())
    {
        // must use defaults, which we can reproduce with math in the shader
        if (renderer->GetDefaultLightRamp() != rampTexture_ ||
            renderer->GetDefaultLightSpot() != shapeTexture_)
            return false;
    }

    // Although analytic it doesn't make sense for a directional light to not cast-shadows except
    // in some really odd situations (non-photoreal)
    if (lightType_ == LIGHT_DIRECTIONAL)
        return false;

    // Must not cast shadows to be analytic
    return !GetCastShadows();
}

Chopping lights into analytical and non-analytical lights means you can bunch them up according. Analytical lights can just be pumped through a renderpass in bulk repurposing the vertex-lighting basepass, while non-analytical lights require proper passes.

Today I see what I did wrong years ago, but it's impossible to implement in current Urho3D core.

[github-actions]

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