Scoring each adjacent i16 slot pair of the 16-byte tie vertex for 12-bit
fixedness over 36,501 level-0 vertices locates the fields:
(i16[0], i16[1]) 1.1% not a texcoord
(i16[2], i16[3]) 4.8% not a texcoord
(i16[4], i16[5]) 73.6% <- the texcoords
(i16[6], i16[7]) 76.6% <- the near-constant 4096/0 pair
(6,7) scores HIGHER and is not a texcoord. It is the near-constant 4096, 0 pair:
4096 is 1.0 in 12-bit fixed and 0 is zero, so both are trivially multiples of
4096. That is the constant artifact again -- a fixed pair would score 100%
anywhere. The field is (4,5), with (0,1) and (2,3) ruled out at 1.1% and 4.8%.
The first four slots span the full i16 range with 10,803 to 13,421 distinct values
each, so they are neither texcoords nor small fields.
The vertex base is confirmed to be vert_ofs alone. Adding the shader or control
region makes it worse --
vert_ofs only 73.6%
bfc + vert_ofs 69.8%
bfc + control_count*control_size + vert_ofs 66.7%
-- so the 73.6% residual is not a mislocated base. Worth recording because
vert_ofs (3..7) numerically overlaps the shader region (5*shader_count, 5..20
quadwords), which made a combined base look plausible; measurement says the
simple one is right.
The test asserts (4,5) above 60% and (0,1)/(2,3) below 5%/15%, and names the
(6,7) artifact in its failure message so the higher-scoring pair cannot be
mistaken for the answer later.
ReaperOfVeriod
180fc27b04