Remove isInterior restriction from WMO shadow sampling so city
buildings (flagged as interior groups) correctly receive shadows.
Apply shadow to interior-lit surfaces. Enable shadows by default
and persist the setting across sessions.
Replaces single-tap shadow sampling with 3x3 grid PCF (36-sample equivalent
with hardware bilinear filtering) for smooth shadow edges. Adds normal-offset
bias to eliminate shadow acne on oblique surfaces without peter-panning.
POM fixes: use blurred height only for ray march (keep crisp Sobel for
normals), reduce pomScale 0.03→0.012, clamp grazing angle denominator
to 0.15, hard-limit max UV offset, smooth fadeout at steep view angles.
Add Normal Map Strength slider (0.0-2.0) in Video settings for user
control over surface detail intensity. Persisted across sessions.
Generate normal+height maps from diffuse textures at load time using
luminance-to-height and Sobel 3x3 filtering. Compute per-vertex tangents
via Lengyel's method for TBN basis construction.
Fragment shader uses screen-space UV derivatives (dFdx/dFdy) for smooth
LOD crossfade and angle-adaptive POM sample counts. Flat textures
naturally produce low height variance, causing POM to self-select off.
Settings: Normal Mapping on by default, POM off by default with
Low/Medium/High quality presets. Persisted across sessions.
Dedicated Vulkan pipeline with alpha blending AND depth writes so
windows look transparent at oblique angles without see-through artifacts.
Fresnel alpha ranges from 0.4 (grazing) to 0.95 (head-on) with sun
glint, reflections, and silver-lining specular.
