sp3d extrusionH (with extrusionClr, srgb or scheme) under a camera that
turns the shape now draws the shape's sides: its outline swept from the
back face to the front along the camera's view of the depth axis, in the
side colour shaded, before the face. camera::project3 projects points
off the shape's plane.
A shape seen through a 3-D camera preset (isometric, perspective...) or
turned with a:camera/a:rot drew flat and front-on. PowerPoint turns the
shape's plane in space and projects it. Fitted black-box to its exports
(a picture with coloured corner markers under every preset and several
rotations; every fit within half a point on a 100 x 75 pt shape): points
about the centre are turned Rz(-rev) Rx(lat) Ry(lon), perspective cameras
then dividing by D / (D - z) with D about 5-16 shape sizes; a:rot turns
the other way about the horizontal and vertical axes. DeckCraft now draws
the shape under the affine transform that best fits its turned corners:
exact for orthographic cameras, within 2% of the size for perspective
ones (an affine map can't foreshorten). Oblique cameras leave a flat
shape as it is; depth (extrusion) is not drawn.
Wild synthetic set: camera presets 15.02 -> 6.35, 3-D picture styles
16.00 -> 7.72, extruded cameras 21.41 -> 19.74.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Nikita Rakitin