2025-04-13

Last modified: 2025-04-13 13:34:06

Bulging blends

It did occur to me that if every surface had a different id then maybe the bulging wouldn't happen? Because you wouldn't be applying the blend to the coplanar surfaces?

So let's try that out.

Before:

That's 2 10x10x10 cubes, one translated by 5 mm in X and 5mm in Y, and with a 3mm fillet.

So now I need to make BoxNode give a different surface id on each side.

OK, I did that. It is annoying to add a blend between these surface ids, because blends need to take node references even though they only care about ids. I hardcoded a blend between the ideas I care about.

But TreeRewriter is not managing to successfully rewrite the tree to satisfy the blends. And the reason is that it can only satisfy a blend by rewriting the tree to make those blend surfaces into sibling children of some combinator. And since it can't split up a BoxNode into multiple surfaces to be Unioned separately, it can't satisfy the blend.

So an alternative is to actually make the Box out of the Intersection of 6 half-spaces. And if that is good then I can fix the broken distance field that it causes.

OK, I have made it form Boxes out of the Intersections of 6 half-spaces. But it's still not managing to apply blends to them.

Oh, derp. I made it do Intersections of half-spaces with structmax - but the TreeRewriter is operating on the level of TreeNode. So I need the BoxNode makeNormalised() to return an IntersectionNode with 6 half-spaces as children.

Whoa! Check it out:

That's 2 cubes made out of 6 half-spaces each, with 2 blends applied.

So yes, this works for preventing blends from bulging! Finally, something works.

Issues currently are:

• hover/select on the cube surfaces doesn't work
• blend ids hardcoded
• surface ids change every time the scene is recompiled
• ignores the Box's radius parameter
• Box distance field is now wrong

Also do you reckon the fillet doesn't look like a true circle? May want to address that at some point.

So I kind of need a way for a TreeNode to reserve a bunch of surface ids instead of just having one.

This is on the "half-spaces-fiddle" branch. So plan tomorrow is to solve the issues from above, and then expand this to work with other objects that obviously have multiple surfaces, like Cylinder and Extrude.