The indexed twin of writeMergedTriangleIdentity, for a merged
group's region in an indexed scene's triangle buffer (words, 4 words per
16-byte unit; the group's first triangle at unit triangleOffset). Each
triangle's word 3 gets the source mesh's triangle index, its filter flag
kept and the flip flag for a mirrored source. The region before the header
(indexedLeadingUnits(triangleCount, sources) units before
triangleOffset) gets the side table (per tree slot: source slot | material
code << 16) and the source table (per slot: instanceIndex), and the
header their distances. The header's vertex base is the caller's.
Call it once on fresh indexed triangles (it reads the builder's original
index); a word 3 with any bit but the filter flag above the index throws.
The indexed twin of writeMergedTriangleIdentity, for a merged group's region in an indexed scene's triangle buffer (
words, 4 words per 16-byte unit; the group's first triangle at unittriangleOffset). Each triangle's word 3 gets the source mesh's triangle index, its filter flag kept and the flip flag for a mirrored source. The region before the header (indexedLeadingUnits(triangleCount, sources)units beforetriangleOffset) gets the side table (per tree slot: source slot | material code << 16) and the source table (per slot:instanceIndex), and the header their distances. The header's vertex base is the caller's.Call it once on fresh indexed triangles (it reads the builder's original index); a word 3 with any bit but the filter flag above the index throws.