EEVEE-Next: Split Thickness Approximation #113401

Clément Foucault · 2023-10-07T23:11:04+02:00

Clément Foucault commented

2023-10-07 23:11:04 +02:00

This moves the thickness from shadow map
approximation out of the lighting and shadowing
loop. Instead of using the thickness from
the shadow tracing from each individual light
before SSS evaluation, we precompute the
average thickness from all shadowed light.
This is then mixed with the nodetree thicknes.

Pros

Reduces complexity of the shadow and light evaluation (speedup).
Allows better shadowing: anything after the computed thickness
is considered shadowing instead of trying to compute thickness for
each light.
Allows unshadowed lights to reuse the thickness computed from
shadowed light.
The thickness now become a split parameter that can be evaluated
using different method and more parameters.
Make thickness effects compatible with forward pipeline and Shader
to RGBA.

Cons

SSS translucency is less precise but this is hard to notice in practice.

SSS Translucency

This add back SSS transmission support by using the above thickness
computation, and applying the transmission profile on it. This is
then applied on top of a flipped normal LTC computation.

Example

In this example the red light does not cast shadow but still reuses the
thickness reconstructed by the other 2 shadowed lights.

Light without sss contribution	Light with sss contribution

This moves the thickness from shadow map approximation out of the lighting and shadowing loop. Instead of using the thickness from the shadow tracing from each individual light before SSS evaluation, we precompute the average thickness from all shadowed light. This is then mixed with the nodetree thicknes. ## Pros - Reduces complexity of the shadow and light evaluation (speedup). - Allows better shadowing: anything after the computed thickness is considered shadowing instead of trying to compute thickness for each light. - Allows unshadowed lights to reuse the thickness computed from shadowed light. - The thickness now become a split parameter that can be evaluated using different method and more parameters. - Make thickness effects compatible with forward pipeline and Shader to RGBA. ## Cons - SSS translucency is less precise but this is hard to notice in practice. ## SSS Translucency This add back SSS transmission support by using the above thickness computation, and applying the transmission profile on it. This is then applied on top of a flipped normal LTC computation. ### Example In this example the red light does not cast shadow but still reuses the thickness reconstructed by the other 2 shadowed lights. | Light without sss contribution | Light with sss contribution | | - | - | | ![Capture d’écran 2023-10-07 à 21.58.30](/attachments/9b7655f5-2449-4b54-9dc7-7a1119fa3277) | ![Capture d’écran 2023-10-07 à 21.58.40](/attachments/eec23520-7509-436a-8552-a2f5cc2db218) |

Capture d’écran 2023-10-07 à 21.58.30.png

1.2 MiB

Capture d’écran 2023-10-07 à 21.58.40.png

1.2 MiB

❤️ 2

Clément Foucault added this to the 4.1 milestone 2023-10-07 23:11:04 +02:00

Clément Foucault added the

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EEVEE-Next: Split Thickness Approximation #113401

Pros

Cons

SSS Translucency

Example