Alpha Piscium’s shadow system combines two advanced techniques to deliver sharp, detailed shadows close to the player and realistically soft shadow edges at distance. RTWSM (Rectilinear Texture Warping Shadow Mapping) dynamically redistributes shadow-map texels so that the most visually important parts of the scene — the area in front of you, surfaces facing the camera, shadow edges — receive more detail. PCSS (Percentage Closer Soft Shadows) then filters those shadow samples with a variable-radius kernel, producing wide, blurred penumbras far from a caster and crisp contact shadows directly beneath objects. Together they make Alpha Piscium’s shadows both perceptually accurate and highly configurable.Documentation Index
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Base Shadow Settings
Resolution and Distance
Resolution and Distance
Higher values produce sharper, more detailed shadows but reduce performance. Valid values:
1024, 2048, 3072, 4096.How far from the player shadow maps are rendered, in blocks.
| Value | Equivalent |
|---|---|
64.0 | 4 chunks |
128.0 | 8 chunks |
192.0 | 12 chunks |
256.0 | 16 chunks |
384.0 | 24 chunks |
512.0 | 32 chunks |
RTWSM — Rectilinear Texture Warping Shadow Mapping
RTWSM is an advanced technique that adaptively allocates more shadow detail based on both the view and the scene. Instead of distributing shadow-map texels uniformly across the render distance, it warps the shadow projection so that regions of high visual importance — surfaces the camera is looking at, areas near the shadow boundary — receive a disproportionately large share of the available texels. This effectively delivers higher-than-nominal shadow quality near the player without requiring a larger shadow map. RTWSM splits importance analysis into two complementary passes: Forward analysis (what the camera is looking towards) and Backward analysis (information coming from the light source, such as which surfaces are lit and where shadow edges fall).Forward Importance Analysis
Forward Warping Parameters
Forward Warping Parameters
Enables forward importance analysis. When active, the shadow warp allocates more texels in the view direction.
Base importance weight for the forward analysis pass. Higher values increase the overall influence of the forward direction on shadow warping. Range
0.1–10.0.Minimum importance value for forward importance analysis. The actual minimum is calculated as
2^x. Range -20–0.Reduces weight based on distance from the camera. Larger values mean slower decay — distant areas retain more importance. Range
0.0–2.0.Backward Importance Analysis
Backward Warping Parameters
Backward Warping Parameters
Enables backward importance analysis. When active, surfaces lit by the sun/moon and shadow edges contribute to the warp.
Base importance weight for the backward analysis pass. Higher values increase the overall influence of light-facing surfaces. Range
0.1–10.0.Minimum importance value for backward importance analysis. The actual minimum is calculated as
2^x. Range -20–0.Reduces weight based on distance. Larger values mean slower decay, giving distant lit surfaces more importance. Range
0.0–2.0.Adds extra importance weight to surfaces perpendicular to the light direction (i.e., surfaces the light grazes across). Range
0.0–4.0.Adds extra importance weight to surfaces directly facing the camera. Concentrates texels on the most visible geometry. Range
0.0–10.0.Adds extra importance weight for shadow edges. Higher values dedicate more texels to the boundary between lit and shadowed areas, sharpening penumbras. Range
0.0–10.0.PCSS — Percentage Closer Soft Shadows
PCSS produces realistic soft shadow edges whose blur radius depends on how far a surface is from its shadow caster. A block sitting directly on the ground casts a sharp contact shadow; the same block suspended in the air casts a large, diffuse penumbra. The blocker search phase first estimates the average depth of nearby occluders, and the sampling phase then applies a kernel of that computed size.PCSS Quality
PCSS Quality
Number of samples used to determine shadow softness (the blocker search). Higher values improve blur-radius accuracy but reduce performance. Valid values:
1, 2, 3, 4, 6, 8, 12, 16.Number of samples used for PCSS shadow filtering. Higher values improve quality by reducing banding in soft shadows but reduce performance. Valid values:
4, 6, 8, 12, 16, 24, 32, 48, 64.Penumbra Size
Penumbra Size
Base Penumbra Factor — a constant amount of blur applied to all shadows regardless of caster distance. Increase this to add a minimum softness even for contact shadows. Range
0.0–10.0.Variable Penumbra Factor — how much shadows blur as a function of distance from the caster. This value is multiplied by the angular size of the sun, so a larger sun (configured in Sun & Moon settings) automatically produces softer shadows. Range
0.0–2.0.