The public 3D and Materials panel options give Perspective as 0° to 160°
("how close or far the object appears"); it was a 0–100 % strength, for
Revolve, Extrude & Bevel, Inflate and Rotate alike.
- The eye stands where a sphere about the object's centre, √3 times its
half size (the box around it fits inside), fills that angle of the
view: 0° is none, wider brings the eye nearer, and at 160° it is just
outside the sphere, never inside the object. The documentation doesn't
say how the angle places the eye; docs/three-d.md says this is our
reading.
- `perspectiveAngle` (degrees) replaces `perspective` (%). A strength from
an earlier file or script is read as the angle that shows exactly the
same view: sin(angle / 2) = √3 × strength / 4, 100 % about 51.3°. An
angle given too wins. effect.setParams turns a stored strength into the
angle before applying new values. The parameter description names
`perspective` as the earlier form, so effect.apply and effect.setParams
still take it under the key check of #1592. Old and new code draw the four effects identically at 0, 25,
60 and 100 % (bounds equal to 1e-9).
- The dialogs' Perspective fields run 0–160°.
# Conflicts:
# docs/target-app-parity.md
39db6abfce