feat(sdf3d): IBL / environment reflections on the SDF path (ADR-0060 Phase 2) - #359
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jeffcrouse wants to merge 3 commits into
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feat(sdf3d): IBL / environment reflections on the SDF path (ADR-0060 Phase 2)#359jeffcrouse wants to merge 3 commits into
jeffcrouse wants to merge 3 commits into
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…Phase 2) Vivid's IBL was dormant — the ENVIRONMENT-fragment machinery + a fallback cube existed in Render3D, but no operator produced an environment, so neither meshes nor SDF surfaces got reflections. Phase 2 builds the source and wires it into the raymarched SDF path (finishing ADR-0060's unification; folds in Phase 3's 'one environment + procedural fallback'). - New Environment operator: bakes a procedural dark-stage sky OR a loaded equirectangular .hdr into irradiance + GGX-prefiltered cubemaps + a split-sum BRDF LUT, and emits the ENVIRONMENT scene fragment. HDR path: stbi_loadf -> RGBA16Float -> an equirect->cube pass; the procedural sky is the asset-free fallback. - Shared create_ibl_bind_group_layout() in gpu_3d.h + a custom_ibl flag on VividSceneFragment, so SDF3D's group-1 IBL layout is group-equivalent to Render3D's group 2 and Render3D's existing real/fallback IBL bind groups bind onto the SDF pipeline unchanged (no new fallback machinery). - SDF3D: a group-1 IBL slot on the pipeline + split-sum ambient/specular terms in the shader (reusing the Phase 1 F0/NdotV/roughness), gated on has_environment. Render3D binds the scene IBL (or the black fallback) at group 1 on the custom SDF dispatch. - blob demo reflects a committed royal_esplanade 1k HDRI (Poly Haven, CC0); BLOB_HDRI=/path overrides, BLOB_HDRI='' selects the procedural sky. Verified: full ctest green, 0 GPU validation errors; a Render3D mesh sphere, an SDF3D sphere, and the blob metaballs all reflect the environment (procedural + real 1k/4k HDRIs). ABI stays additive; vendored gpu_3d.h snapshots synced. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Production gate (core): ✅ PASS
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The split-sum BRDF LUT was generated with roughness = 1 - uv.y but sampled at vec2f(NdotV, roughness), so the roughness axis was FLIPPED — every IBL surface read the BRDF response for (1 - its roughness). Generate it as roughness = uv.y to match the sampler. Fixes the energy/appearance of all IBL (mesh + SDF). Also bump the base/prefiltered cube to 256^2 and the GGX prefilter to 256 samples for a crisper reflection. Known limitation (follow-up): the single-mip GGX prefilter shows coherent-sample rings on a near-perfect mirror (roughness -> 0); glossy surfaces (the blob demo) are clean. The proper fix is PDF-based mip sampling of the environment, which needs a base-cube mip chain. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
… in an HDR hall A dedicated ADR-0060 Phase 2 showcase: a near-mirror SDF sphere reflecting a loaded royal_esplanade equirect HDRI via image-based lighting, with the same environment drawn as the skybox behind it. An orbit camera (Clock-driven) plus a faint tarnish (subtle roughness smudges + fine scratches, committed maps) make it obviously a rotating reflective object; no direct lights — everything on the ball is reflected environment. The slight gloss also hides the single-mip prefilter rings a perfect mirror would show. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Builds on the merged Phase 1 (#357). Makes SDF metaballs reflect a real environment — the last big visual gap between the SDF path and the mesh path.
The discovery
Reading the code first revealed Vivid's IBL was entirely dormant: the
ENVIRONMENT-fragment machinery + a fallback cube existed in Render3D, but no operator ever produced an environment, so meshes had no reflections either. So Phase 2 couldn't be "bind the existing cubemaps" — it had to build the source. (This also delivers ADR-0060's Phase 3 goal.)What's in it
Environmentoperator — bakes a procedural dark-stage sky or a loaded equirect.hdrinto irradiance + GGX-prefiltered cubemaps + a split-sum BRDF LUT (all render-pass based, cached), emits theENVIRONMENTfragment. HDR:stbi_loadf→ RGBA16Float → an equirect→cube pass.create_ibl_bind_group_layout()(gpu_3d.h) + acustom_iblfragment flag — so SDF3D's group-1 IBL layout is group-equivalent to Render3D's group 2, and Render3D's existing real + fallback IBL bind groups bind onto the SDF pipeline unchanged.F0/NdotV), gated onhas_environment. Render3D binds the scene IBL (or the black fallback) at group 1 on the custom SDF dispatch — one added block.media/blob/);BLOB_HDRI=/pathoverrides,BLOB_HDRI=''uses the procedural sky.Verification
Render3Dmesh sphere, anSDF3Dsphere, and the blob metaballs all reflect the environment — procedural dark-stage sky (cyan/magenta studio reflections on the wet liquid metal) and real CC0 HDRIs (studio / day / night / royal_esplanade). All were byte-black on the SDF path before.boolfragment field; group-1 is pipeline-internal). Vendoredgpu_3d.hsnapshots synced (guard passes).Follow-up (not blocking)
Skybox/IBL render without tone mapping, so a bright HDRI blows out the background (the reflection is correct) — an exposure/tonemap control is a good later add.
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