Negative on purpose, and it is the one default in this file that is not
quoted from the specification. A screen camera exists to draw content
authored on the plane it sits on — panel.position.set(24, 24, 0) with the
camera at the origin — and the shared Camera default of near = 0.1 puts
the near plane just in front of that content, so a camera nobody moved
would render nothing. (That trap is recorded twice already: R-8 found three
integration harnesses asserting draws for frames where "a camera at the
origin cannot see z = 0".) A parallel projection has no reason to avoid it:
unlike a perspective frustum, an orthographic box may straddle the eye, so
the honest default is a symmetric slab that contains z = 0 with a thousand
units of ordering room on each side for stacked UI.
Default near plane of a ScreenCamera:
-1000.Negative on purpose, and it is the one default in this file that is not quoted from the specification. A screen camera exists to draw content authored on the plane it sits on —
panel.position.set(24, 24, 0)with the camera at the origin — and the sharedCameradefault ofnear = 0.1puts the near plane just in front of that content, so a camera nobody moved would render nothing. (That trap is recorded twice already:R-8found three integration harnesses asserting draws for frames where "a camera at the origin cannot seez = 0".) A parallel projection has no reason to avoid it: unlike a perspective frustum, an orthographic box may straddle the eye, so the honest default is a symmetric slab that containsz = 0with a thousand units of ordering room on each side for stacked UI.