Scenario Godot Rendering Lighting

Godot rendering and lighting (lighter / graphics technical artist)

Target: Godot 4.7.2.stable, macOS Apple Silicon (Metal by default).

Expert level here means that lighting comes from a measured loop: a calibration scene, one variable at a time, a rendered image looked at after every change, numbers on that image, and a GPU cost for every effect. The renderer and the GI method are chosen first, because they decide what the other settings can do. The art direction (value pattern, warm and cool, focal contrast) is judged on pixels the agent actually opened, never on the inspector. If a sibling skill named here is missing from your available skills, ask the user to install it (npx skills add scenario-labs/skills --skill <name>); unattended, proceed from tool schemas and flag the gap.

REQUIRED BACKGROUND: scenario-godot-expert (channels, gd_run, the review loop, 4.7 traps).

Stance (the expert delta)

1. Use lightmaps for static scenes. SeasonalAsh measured on an RTX 4060 that SDFGI roughly halves fps, VoxelGI runs at 60 to 80 fps, and lightmaps are fastest: lightmaps "9 times out of 10" unless the world is destructible (SeasonalAsh 13:07, 17:48). In 4.7.2 an agent can bake them: the editor job presses "Bake Lightmaps" itself (P7). Dynamic geometry or a moving sun means SDFGI or VoxelGI; static means LightmapGI plus ReflectionProbes.
2. Calibrate on a lookdev scene before lighting the level. Brackeys uses guide spheres (dark, white, mirror) and Display > Lighting (Brackeys 7:19, 28:53). Picster keeps the primitive blockout for later retests (Picster 2:05, 1:15:35). lookdev.gd builds an exterior and a sealed room.
3. Pick the tonemapper by look, then retune exposure. Brackeys and Wild Ox use AgX; SeasonalAsh and LegionGames use ACES. Measured: AgX gives the lowest p95, no clipping, and keeps an orange emitter orange where Filmic and ACES push it to yellow (P5). AgX is also the costliest tonemapper, which matters on phones (docs). A new Environment is Linear (P1): always set it.
4. Make emission readable on two levels. Glow makes an emitter look bright; a real light (or baked GI) makes it light the scene (Brackeys 13:56, Gamefromscratch 7:09). Glow defaults changed in 4.6 (Screen, intensity 0.3, levels 2 to 4 at 0.8/0.4/0.1, P15): retune scenes made before 4.6.
5. Never use SDFGI and VoxelGI together, and never trust SDFGI on frame one. SDFGI converges in about 30 frames (P1) and is darker right after enabling (P8). GDQuest retunes the tonemap after turning it on.
6. Volumetric fog quality lives in Project Settings, and that is where its cost is. Four Games calls volume size 64 too low and 256 a good compromise; god rays need anisotropy about 0.7 and a shorter length (Four Games 0:32 to 3:52). Raise one hero light's Volumetric Fog Energy, drop a flashlight's to 0.1 (Brackeys 19:52, LegionGames 2:08). Measured: 512 costs +3.9 ms at 1080p (P9).
7. The base look must hold on every renderer; tiers only add. Mobile ignores SDFGI, VoxelGI, SSR, SSAO, SSIL and volumetric fog; Compatibility the same minus SSAO; each prints one WARNING line at load (P4). Fog, glow, tonemap, lightmaps and probes carry the look everywhere [added]. Renderer fallback to Compatibility is silent since 4.4 and fallback_to_opengl3 defaults to true (docs, P15): set it false on PC so a bad driver fails loudly; on Android keeping it true is a choice, so test the Compatibility look.
8. CompositorEffect is GLSL compute, not .gdshader (Acerola 9:39). The docs list Forward+ and Mobile, but the docs pattern (color as a storage image) logs 172 errors on Mobile in 4.7.2 because Mobile's color buffer lacks the storage bit, and Compatibility ignores the effect silently (P12). Ship it on Forward+ and guard Mobile. Callbacks run on the render thread: mutex any state shared with the main thread, pad push constants to multiples of 16 bytes, and remember upscaling runs after post (docs). For post with UI on top, a CanvasLayer ColorRect works everywhere (Lukky).

Establish first

Workflow

Load the toolkit: sys.path gets skills/scenario-godot-expert/scripts and skills/scenario-godot-rendering-lighting/scripts, then import gd_lighting as gl and gl.install(P). Full code: references/procedures.md.

1. Renderer. Read project.godot (rendering_method, Jolt, fallback) (P1). gl.capture_renderers(P, scene) captures one view per renderer and returns the WARNING lines. GATE: renderer written in project.godot; parity sheet opened; dropped features listed in the handoff.
2. Lookdev. gl.build_lookdev(P) (P3), capture the three cameras. GATE: look_checks p95 minus p05 above 0.25, clipped under 5 percent; opened: dark sphere shows form, white not clipped, mirror reflects sky.
3. GI and bake.
   • static: gi_bake.gd:prepare (sun Dynamic, others Static, hidden lights Disabled, UV2 check), then the windowed gi_bake.gd:lightmap editor job (P7);
   • mid-size dynamic: gi_bake.gd:voxelgi, windowed (P6);
   • open world: SDFGI with occlusion, bounce feedback 0.5 or less, Y scale 75 or 50 percent, max distance below camera far, captured after 40 frames or more (P8).
   • Add ReflectionProbes with lightmaps (no specular otherwise). GATE: audit has no GI errors; bake files exist; interior capture opened and checked for leaks, seams and dark patches.
4. Key, fill and practicals. Lights at their sources, matching color; shadows only on key lights; candles unshadowed, short range; artificial lights below the sun (Brackeys, SeasonalAsh). Run gl.audit(P, scene, ["forward_plus", "mobile"]) (P2). GATE: no error flags; squint(img) opened with one focal value; focal_contrast at least 0.05.
5. Environment and post. gl.sweep one variable at a time: tonemapper (tonemap_variants, P5), exposure, glow, fog, volumetric fog (P10), Adjustments last (cool shadows, warm lights via the color-correction gradient, Picster 45:07). GATE: each sheet opened, winner named with its numbers, no variant clipping over 5 percent unless briefed.
6. Shadows. Sweep shadow_normal_bias first, then shadow_bias (SeasonalAsh 0.05 against the 0.1 default, frames 4:13); blend splits on; max distance set to the playable range (Picster 400 outdoors, default 100). GATE: grazing-angle close-up opened, no stripes, contact shadow attached.
7. Tiers and cost. graphics_tiers.gd presets through a sweep with call and measure=60 on --rendering-driver vulkan (P11): low and medium use 2 shadow splits, high and ultra 4. Per-effect deltas from the P9 template. On Mobile use MetalFX spatial on Apple, else bilinear (P13). GATE: each tier's GPU ms fits the budget on the target renderer, and the low tier keeps the mood.
8. Custom post (optional). compositor_tools.gd:attach plus post_effect.gd and a GLSL compute shader (P12). GATE: the effect shows on Forward+; Mobile skips with one warning.