The Casts Shadows option Environment lights got is only half a fix if
nothing shades for it: an image lights the scene from every direction,
and what occludes that light is the image itself — its dominant bright
region, the sun in a sky map.
- dominant_direction finds it: the radiance-weighted mean texel
direction (solid-angle weighted, rotation applied). A uniform image
cancels to zero — a flat default environment shines from everywhere
at once and casts no shadow, which a uniform environment test pins.
- The shadow is one orthographic map over the scene from that
direction, after the lights' maps, like a parallel light's: PCF
widened by Shadow Diffusion, darkened by Shadow Darkness, cleared
when nothing casts, the image is directionless, or the texel budget
drops it.
- It darkens the environment's own diffuse and specular light on
Accepts Shadows surfaces and counts in Cast Shadows Only. CPU and
GPU (WGSL) do the same; Globals carries the environment's sun
direction and shadow settings (40 → 44 floats, preflight updated).
A bright-disc environment turned to shine from behind the camera now
shadows a sphere onto the floor behind it, Cast Shadows off lights it
evenly again, and the GPU scene's sky gradient takes a shadow-casting
Environment light. Also: the renderer-switch toasts read "...renderer,
which draws 3D models", the dialog's Casts Shadows checkbox gets an
auto id (dialog.light.casts) the tests click, and the docs' Environment
notes cover the shadow.
Minher0
863f0e49c1