The overlay used to clip and affine-map a code texture onto every
visible roof and punch every roof out of a 2D ground grid each frame
(about 13,600 saves and 6,800 clips per frame on a 1,676-file repo).
The existing code overview canvas already matches the world layout, so
it is uploaded once as a mipmapped texture and sampled by the roof
shader. The overlay now only draws sharper text for the few roofs close
enough to magnify that texture, and the grid is a WebGL line pass. The
vertex shader emits a real clip-space w so the texture is perspective-
correct; screen positions are unchanged. JS and canvas time per 3D
frame fell from 284 ms to 27 ms in the same profile.
Andy Dixon
e7627c8877
