Prowl.Photonic 3.2.1

Prowl.Photonic

A CPU lightmap baker for the Prowl Game Engine. Imperative builder API: scene + meshes + lights in, baked HDR atlas pages out. Direct + indirect path-traced lighting, BVH4 + AVX2 SIMD acceleration, progressive accumulation.

Features

• Imperative builder API

  • BakeScene + BakeMesh.Builder + LightmapTarget give you a BeginScene / BeginMesh / End flow
  • Per-instance world transform, per-target atlas placement (offset / scale into the bake UV layer)
  • Auto-atlas packer "drop a list of meshes in, get N atlas pages out"

• Acceleration

  • BVH4 with binary SAH + binned splits, collapsed to 4-wide nodes (SoA Vector128 AABB packs, one SIMD ray-vs-4-AABB per inner-node visit)
  • AVX2 leaves: 8-triangle Moller-Trumbore in Vector256 (LoadUnsafe over SoA edge arrays)
  • Parallel-for over rows, deterministic per-texel seeding

• Lighting

  • Directional, point, spot
  • Next-event estimation at every bounce hit
  • Pluggable IAttenuation (InverseSquare, NormalizedQuadratic, Constant)
  • IncludeDirectLighting for indirect-only bakes, or per-light BakeDirect for mixed lighting

• Sparse sampling

  • SparseStride traces one texel per NxN cell and interpolates the rest from the traced points, which converges dramatically faster on indirect

• Artifact fixes

  • Conservative SAT-based texel rasterisation with centroid bias and strict-inside-wins claim semantics
  • Samples pushed out of solid geometry, stepping past the nearest wall
  • Phong-tessellated shading position, with per-triangle fallback to flat where the smooth position is occluded
  • UV seam stitching and edge dilation

Usage

using var baker = new LightmapBaker();
baker.Options.Bounces = 2;
baker.Options.SamplesPerIteration = 1;
baker.Options.IncludeDirectLighting = true;

var target = baker.CreateTextureTarget("atlas0", 512, 512);
var scene  = baker.BeginScene("Sponza");

var mat = scene.CreateMaterial("floor");
mat.DiffuseColor = new Float3(0.8f, 0.8f, 0.8f);

var mesh = scene.BeginMesh("floor")
                .AddVertices(positions, normals)
                .AddUVLayer("UV0", materialUVs)
                .AddUVLayer("UV1", lightmapUVs)
                .AddMaterialGroup("floor", indices)
                .End();
target.AddBakeInstance(mesh, Float4x4.Identity);

scene.CreateDirectionalLight("sun", Float4x4.Identity, new Float3(8f, 7f, 6f));
scene.End();

var job = baker.Start();
job.RunIterations(64);   // headless: fold 64 iters then stop
baker.Cancel();

byte[] ldr = target.ReadLDR(exposure: 1f, gamma: 1f / 2.2f);

License

MIT. See LICENSE.