A piece of code, I want to know his inner workings

[shanfl]

There is a piece code in file 'sources/engine/Stride.Rendering/Rendering/Lights/LightClusteredPointSpotGroupRenderer.cs', I find it in many project ,like tiled forward rendering . but I reall hard to understand what it mean .

private static void UpdateClipRegion(
                        float lc,          // Light x/y coordinate (view space)
                        float lz,          // Light z coordinate (view space)
                        float lightRadius,
                        float cameraScale, // Project scale for coordinate (_11 or _22 for x/y respectively)
                        float cameraOffset, // Project offset for coordinate (_31 or _32 for x/y respectively)
                        ref float clipMin,
                        ref float clipMax)
            {
                float rSq = lightRadius * lightRadius;
                float lcSqPluslzSq = lc * lc + lz * lz;
                float d = rSq * lc * lc - lcSqPluslzSq * (rSq - lz * lz);

                '''
            }

In begin of this function , there is

                float rSq = lightRadius * lightRadius;
                float lcSqPluslzSq = lc * lc + lz * lz;
                float d = rSq * lc * lc - lcSqPluslzSq * (rSq - lz * lz);

I wonder about his rationale! plz.

[tebjan]

What exactly do you want to know, do you suspect a bug there? Here is a high-level explanation:

The overall goal of this function is to update the minimum and maximum clipping regions (clipMin and clipMax) for the light within the view frustum. This is part of a broader clustered shading algorithm to determine which clusters (regions of the screen space) are affected by each light, optimizing the rendering process by reducing unnecessary light computations.

Summary

• The calculations determine if the light intersects the view frustum.
• The discriminant (d) checks for real intersection points.
• If intersections exist, the function computes the tangent planes' normal vectors.
• These vectors update the clipping region to define where the light affects the view frustum.

This method is crucial for optimizing rendering in clustered shading by accurately determining the light's influence within the view frustum.