Function maybeLookupIndex

src/SplatMesh.ts:1197–1245

(
  lodIndices: DynoUsampler2D<"lodIndices", THREE.DataTexture>,
  index: DynoVal<"int">,
  numSplats: DynoVal<"int">,
  enableLod: DynoVal<"bool">,
  showLodPage: DynoVal<"int">,
)

}

export function maybeLookupIndex(
  lodIndices: DynoUsampler2D<"lodIndices", THREE.DataTexture>,
  index: DynoVal<"int">,
  numSplats: DynoVal<"int">,
  enableLod: DynoVal<"bool">,
  showLodPage: DynoVal<"int">,
) {
  return dyno({
    inTypes: {
      lodIndices: "usampler2D",
      index: "int",
      numSplats: "int",
      enableLod: "bool",
      showLodPage: "int",
    },
    outTypes: {
      index: "int",
    },
    inputs: {
      lodIndices,
      index,
      numSplats,
      enableLod,
      showLodPage,
    },
    statements: ({ inputs, outputs }) =>
      unindentLines(`
        int index = ${inputs.index};
        if (${inputs.showLodPage} < 0) {
          if (index >= ${inputs.numSplats}) {
            return;
          }
          if (${inputs.enableLod}) {
            ivec2 lodIndexCoord = ivec2((index >> 2) & 4095, index >> 14);
            uint splatIndex = texelFetch(${inputs.lodIndices}, lodIndexCoord, 0)[index & 3];
            ${outputs.index} = int(splatIndex);
          } else {
            ${outputs.index} = index;
          }
        } else {
          int start = ${inputs.showLodPage} << 16;
          if (index >= 65536) {
            return;
          }
          ${outputs.index} = start + index;
        }
      `),
  }).outputs.index;
}

export function maybeInjectSplatRgba(
  gsplat: DynoVal<typeof Gsplat>,