Modernize TEN lighting with HDR, GGX materials, bloom and softer shadows

[illyaine]

Summary

This draft consolidates the ongoing TEN lighting modernization in one branch and one pull request.

Modern direct lighting

• Add a shared modern lighting path for room geometry, moveables, instanced statics and inventory objects.
• Replace the old reflection-vector highlight with a dielectric Cook-Torrance GGX BRDF.
• Use the real per-pixel camera-to-surface view vector instead of a global camera direction for specular highlights.
• Keep existing AO, roughness, specular, height and emissive material maps authoritative.
• Do not simulate metallic materials because TEN currently has no metalness channel.
• Convert legacy vertex sheen values into compatible roughness and specular overrides.
• Add derivative-based specular antialiasing to reduce shimmering on detailed normal maps.
• Add basic dielectric energy conservation between direct diffuse and specular lighting.
• Preserve HDR values above 1.0 for bright direct light and highlights.

Light attenuation and selection

• Replace hard linear range edges in the modern shader path with smooth inner/outer range attenuation.
• Add a mild distance response while retaining the ranges and intensities authored for existing TEN levels.
• Smooth spotlight cone transitions.
• Keep the legacy object-lighting path available for direct comparison with F8.
• Add object-bound-aware light collection for moveables and statics.
• Rank lights by local influence instead of always preferring dynamic lights.
• Add selection hysteresis to reduce visible light swapping near influence boundaries.
• Correct spotlight CPU ranking by converting stored cone angles from degrees to cosine space.
• Expand spotlight selection cones by the apparent angular radius of the object's bounding sphere.

Material and reflection response

• Separate indirect ambient lighting from runtime diffuse and specular lighting.
• Keep direct and specular lighting independent from baked AO attenuation.
• Preserve emissive contribution after shadows.
• Correct normal and tangent transforms for non-uniform and mirrored scale.
• Normalize the room tangent basis and initialize room sheen explicitly.
• Make legacy and skybox reflection strength respond to roughness and view-angle Fresnel.
• Reduce reflections on rough surfaces rather than faking unavailable prefiltered reflection mip levels.

Shadows

• Replace the square 5x5 box PCF pattern with a rotated 16-tap Poisson filter.
• Add a real slope-dependent receiver depth bias plus shadow-map texel bias.
• Increase filter radius gradually with receiver distance for less uniform shadow softness.
• Preserve signed projection depth near cube-face boundaries.
• Evaluate shadow strength using the modern point and spotlight attenuation.
• Apply room shadow maps to the full non-emissive surface result, including direct diffuse and specular light.
• Keep emissive materials self-lit after shadowing.

Internal HDR pipeline

• Add an engine-controlled FP16 scene-color path independent of Windows HDR.
• Restrict FP16 promotion to scene-color, SMAA scene, bloom and reflection targets instead of converting all RGBA8 utility targets.
• Keep normals, material masks, SSAO and emissive/material G-buffer targets in their intended formats.
• Preserve HDR precision through bloom composition, FXAA and SMAA.
• Tone-map the FP16 scene before it enters the SDR postprocess chain.
• Avoid applying tone mapping, fade, tint or cinematic bars twice.
• Keep frozen scene and inventory backgrounds compatible with the HDR scene buffer.

Tone mapping, bloom and glare

• Add ACES-style tone mapping with exposure and strength controls.
• Add configurable light bloom, threshold, strength, radius, glare strength and glare length.
• Normalize the bloom downsample kernel so it no longer adds artificial brightness.
• Evaluate bloom using perceptual luminance plus a peak-channel term for saturated colored lights.
• Make bloom threshold evaluation exposure-aware.
• Apply a softer threshold to emissive material sources without making low-intensity emissive maps haze the image.
• Add a small highlight chroma correction to reduce neon channel clipping.
• Skip the glow pass entirely when bloom and glare strengths are both zero.
• Preview all postprocess values directly while the Lighting and HDR page is open.
• Draw the settings UI after tone mapping so text remains stable and is not bloomed.
• Determine restart requirements from the actual active scene render-target format.
• Persist all HDR and bloom options in the TEN graphics configuration.

Current menu integration

• Branch: feature/ten-improved-lighting
• Draft PR retained for iterative testing.
• The existing High Framerate row currently exposes the HDR page through Select and is labelled High Framerate / HDR Settings; Left/Right continues to change the framerate option.
• A fully separate Display-menu row still requires the coordinated central GuiController option-index change and remains pending. No duplicate menu state machine has been introduced.

Validation required

No CI checks are currently attached to this branch. A local Windows build, Direct3D HLSL compilation and in-game comparison are still required, including:

• HDR on/off startup paths and restart handling
• no AA, FXAA and SMAA paths
• title, pause, inventory, loading and frozen-scene rendering
• bloom threshold, strength and radius live preview
• glare strength and length
• saturated red, blue and warm light sources
• rough and glossy material-map extremes
• normal-map shimmer during camera movement
• emissive materials and bright specular highlights
• legacy versus improved object-light selection
• point-light range boundaries
• spotlights near cone edges and on large objects
• shadow acne, peter-panning and cube-face seams
• dynamic statics with WADTool ambient value 128