User-reported live: the torso-twist tape appeared at the TOP of the reticle
(should be bottom) and the range ladder filled the wrong direction. I had
assumed dpl2d used a standard math y-up convention (y0=bottom, y1=top) and
inverted accordingly.
Found the exact, already-solved answer in vrview_gl.py's own HUD vertex
shader comment: "dpl2d Y grows DOWN (screen convention): period VHS footage
shows the twist dial UNDER the reticle and the range bar filling top-to-
bottom; mapping straight onto GL's Y-up NDC rendered the whole HUD flipped"
-- the exact same bug, already diagnosed and fixed there. y0 (the smaller
raw view-rect value) is the TOP of screen, y1 the bottom -- direct mapping,
no inversion needed.
Verified offline: the composited reticle now shows the twist tape (with its
bowtie shape) at the bottom and the range ladder/pips reading top-to-bottom,
matching BT411's documented layout.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>