b3dSetQuadRayRadianceDistance

Sets per-entity screen radiance effect (screen brightening based on camera distance from source, 0=disabled). Takes quadrayEntity (quad ray source entity handle), startRadiance (distance where brightening begins, 0 = disabled), endRadiance (distance where full brightness reached), riseLevel (brightness multiplier 1.0-3.0 typical). Returns nothing. Sets entity.quadRayRadianceStart, entity.quadRayRadianceEnd, entity.quadRayRadianceLevel (per-entity radiance parameters, applied in post-processing). Use for screen glow when approaching light source (sun horizon glow, bright light bloom), proximity effect (screen brightens as camera nears source), or atmospheric depth (distant sources add subtle screen brightening). Radiance effect: camera distance < startRadiance = no effect (radiance disabled, screen normal brightness), startRadiance <= distance < endRadiance = fade in (screen brightness increases linearly, glowing effect grows), distance >= endRadiance = full effect (screen brightness at riseLevel maximum, full glow). Per-entity setting: each quad ray source has independent radiance (sun has large radiance range, torches have small range), independent of ray intensity (rays can be dim but radiance bright, or vice versa), independent of fade distance (radiance affects screen, fade affects ray visibility). Use cases: (1) Sun horizon glow (startRadiance 200, endRadiance 500, riseLevel 1.5 for brightening near sun), (2) Light bulb proximity (startRadiance 5, endRadiance 20, riseLevel 2.0 for glow when close to bulb), (3) Cave exit brightness (startRadiance 30, endRadiance 80, riseLevel 2.5 for glowing cave exit), (4) Distant landmark (startRadiance 500, endRadiance 1000, riseLevel 1.3 for subtle beacon glow), (5) Disable radiance (startRadiance 0, endRadiance 0, riseLevel 1.0 for no screen effect). Common patterns: sun glow = startRadiance 300, endRadiance 600, riseLevel 1.6 horizon brightening; light proximity = startRadiance 10, endRadiance 30, riseLevel 2.2 close-range glow; disabled = startRadiance 0 no effect. Typical values: disabled (startRadiance 0 no radiance), short range (start 5-20, end 20-50, rise 1.5-2.5 for close lights), medium range (start 50-150, end 150-300, rise 1.3-1.8 for standard sources), long range (start 200-500, end 500-1000, rise 1.2-1.6 for distant sources). Radiance formula: radianceFactor = saturate((distance - startRadiance) / (endRadiance - startRadiance)) where saturate clamps 0-1, final brightness = 1.0 + radianceFactor * (riseLevel - 1.0), screen color *= brightness (multiplicative brightening, white becomes brighter, colors saturate). riseLevel parameter: 1.0 = no brightening (neutral, no effect even at endRadiance), 1.5 = 50% brighter (subtle glow, screen colors x 1.5), 2.0 = double brightness (moderate glow, typical for lights), 3.0 = triple brightness (very bright glow, overexposed effect), 1.0-3.0 recommended (higher values wash out screen, extreme glow). Interaction with quad rays: radiance independent of ray visibility (screen can brighten even if rays faded or occluded), typically used together (rays show volumetric light, radiance shows proximity glow), both distance-based (but radiance uses camera-to-source distance, rays use pixel-to-source tracing). Performance: radiance cheap (per-pixel brightness multiply, minimal cost <0.1ms), calculated per source (each source adds radiance, accumulates additively), many sources possible (radiance doesn't involve ray tracing, just distance check and multiply). Validation: only affects isQuadRaySource entities (non-quad-ray entities ignored), silent if entity not found (invalid handle no-op), accepts any values (0 = disabled, negative undefined use 0). Related: b3dLoadQuadRayMesh creates quad ray source (load mesh, then configure radiance), b3dSetQuadRayFadeDistance controls ray fade (independent of radiance, rays can fade while radiance active), b3dSetQuadRaysIntensity global ray intensity (affects rays not radiance, radiance only screen brightening), b3dPositionEntity positions source (radiance calculated from camera to entity.position distance).