Automatically adjust Light3D shadow bias to account for resolution #57638
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| float bias_scale; | ||
| if (directional_shadow.size < 4096) { | ||
| // For shadow map sizes below the default, don't increase bias too much to avoid peter-panning. |
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Technically, we should be using the same formula as with shadow sizes above the default. However, this would result in too much peter-panning, so I went for a half-way compromise between not adjusting the bias at all and adjusting it to match the resolution perfectly.
The bias factors used for each resolution are:
- 256:
8.5 - 512:
4.5 - 1024:
2.5 - 2048:
1.5 - 4096:
1.0 - 8192:
0.5 - 16384:
0.25
This applies to both directional and point light shadows.
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This logic should be different for Point Light Shadows, as you have to have the resolution of the cell the shadow is using, not the entire shadow map.
This would incorrectly change bias for the same effective resolution of shadow if you go from a 4k shadow map with 4 4 4 4 quadrants and change to 8k shadow map resolution with 16 16 16 16 quadrants which effectively results in same resolution, just more shadows available.
Higher shadowmap resolutions make it possible to use lower bias values without exhibiting shadow acne. On the other hand, shadow bias should be increased when using lower shadowmap resolutions (but not as much, to avoid peter-panning).
Calinou
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Follow-up to #55758.
Higher shadowmap resolutions make it possible to use lower bias values without exhibiting shadow acne. On the other hand, shadow bias should be increased when using lower shadowmap resolutions (but not as much, to avoid peter-panning).
The formula was determined empirically and is subject to changes. Nonetheless, I think it's a good start to make graphics settings adjustments easier for users to manage.
The bias values are unchanged at the default shadow size on desktop platforms (
4096).Testing project: test_shadow_bias_auto_resolution.zip
Preview
Each video starts at the highest shadow resolution and progressively decreases to the lowest shadow resolution.
It's recommended to view each video in fullscreen.
Before
Directional shadows
Visible acne at low shadow resolutions, even up close on the cubes. The distant shadow splits in particular are full of acne.
simplescreenrecorder-2022-02-04_19.49.04.mp4
Point light shadows
Visible acne at low shadow resolutions.
simplescreenrecorder-2022-02-04_19.48.38.mp4
After
Directional shadows
No more acne at low shadow resolutions. Shadow resolutions above the default value also have less visible peter-panning.
simplescreenrecorder-2022-02-04_19.45.50.mp4
Point light shadows
No more acne at low shadow resolutions. Shadow resolutions above the default value also have less visible peter-panning.
simplescreenrecorder-2022-02-04_19.46.21.mp4