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ExPikaPaka
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An image laid onto a model came out upside down under the ordinary box (tri-planar) projection, and on three of a cube's six faces it was also mirrored left to right, which reads as a 180 degree rotation. DecodedHeightTexture::sample() defines v = 0 as the height map's first pixel row, i.e. its top. Every projection built v from world +Z, so v grew upward and the image landed bottom row up. The one path that was already right is the projective "project from view" matrix, which measures window y downward. Both halves of the box basis were wrong: - v is now negated on all three world planes, so the top of an image sits at the top of the model. - u now carries a sign for the side of the plane the face is on, chosen so that u x v == -normal. Without it the two faces sharing a plane get one u and one of them is mirrored. The sign flips exactly where that plane's blend weight (the fourth power of a normal component) reaches zero, so the blended tri-planar sum stays continuous and the hard axis switch the old code removed does not come back. The same v convention was missing from the other mapping modes: cylindrical (which also had a left handed frame, right x up rather than up x right, so its wrap ran mirrored), spherical, the affine branch of view projection, and the flat chart fallback of the LSCM unwrap, which now reuses the box basis so a cube face unwraps to the orientation tri-planar would have given it. The basis table is exported as box_projection_axes() and the gizmo's adjust_tangent_basis() calls it instead of restating it, so the placement ring and offset handle cannot drift from the bake. All four preview shaders get the matching change, including projection_axes(), whose tangent and bitangent have to flip with the coordinate or the relief shading inverts. Re-baking an existing project now places its texture upright, so it will differ from how it looked before. Geometry already baked into a 3mf is untouched, so nothing changes until the user re-bakes. Verified by measuring the sampled texture row and column against world position for every mapping mode on all six faces of a cube, and by a full bake of a quadrant coded image, which lands each quadrant within 1e-3 mm of its expected depth.
OrcaSlicer tests
Building, running and writing tests is documented on the wiki, under How to Test.
Two files here rather than there, because coding agents only read what is in the repository: