Fix #50 by refactoring the selection mechanism

[rcarmo]

I noticed that the batch_for_shader function was generating internal errors in Blender 4.4, so I went down that rabbit hole and indirectly fixed all the selection errors I was having - and also refactored the workplane selection.

Right now box selection works, including for overlapping entities (at least as far as I can understand it), so I think this fixes #50 as well

[hlorus]

Hey these are great changes, thanks! I still have some input however:

Overlapping entity selection:

• dosesn't work on my end, is there a modifier key that needs to be hold for it to cycle?
• this would also fix [BUG] Copy-pasting sketches loses some entities #469 and Marquee select does not select small lines #346

Workplane selection:

• the workplane selection doesn't seem to respect depth, so the workplane that is last drawn obscures the other planes, can this be improved?
• it would be great if the edges of the workplane would have priority such that they could also be selected if obscured by another plane

[rcarmo]

No, you should just be able to click to cycle through overlapping entities (I am testing with two lines that partially overlap). Box selection works as far as I can tell.

I will look at the workplace selection a bit better. I was annoyed that I could't select them without clicking the edges because, to be honest, they are very small targets. I might need to track drawing order...

[rcarmo]

Well, I can now pick workplanes through other workplanes, but I can't really get it to work reliably regarding the edges. I think I'll pause this, I've found I can easily select any workplane by moving the mouse to it even through another....

[rcarmo]

If you're OK with this, can we merge this one? I'd like to keep PRs relatively small.

[hlorus]

It behaves a bit weird, when i move the cursor away from the plane it stays hovered, also i cannot manage to select a plane border through another plane.

Screencast.From.2025-05-05.08-08-37.mp4

Normal entity selection is almost entirely broken for me.

[rcarmo]

Well, that's because I am clamping the selection to make it easier to use with a trackpad.

As to the borders, I've tried many things, but I just can't make them be consistently "in front" of the planes and they are very hard to select, even when increasing the tolerance/line width (I dialed that back in my last commit, must have affected the selection because there is just the one constant).

I'll have another go. I can remove the clamping and tweak the tolerances again, but TBH selecting the planes via the borders doesn't seem trivial.

[hlorus]

Amazing, the workplane selection works great! I still get an error when trying to write out the selection texture:
AttributeError: 'NoneType' object has no attribute 'draw'
Traceback (most recent call last):
File "/home/yoga/Dropbox/blend/extensions/CAD_Sketcher/gizmos/constraint.py", line 169, in draw
icon_manager.draw(self.type, col)

Also in the selection texture when a sketch is active i get a big rectangle, it seems that the sketches workplane is still drawn an occludes other entities:

[rcarmo]

Oh, I'm not done yet. I had to turn on workplane drawing to test the selection buffer and also broke constraint drawing. I just ran out of time yesterday.

I might still move some stuff off global_data and into constants (ZAXIS) or utilities as I go along...

[rcarmo]

This is sort of OK-ish now. I am going to test it and then revisit the stacked/overlapping entities thing. I think it's still working, but I haven't tried to actually use it since yesterday.

[hlorus]

The workplane is a 3d element so it should never be drawn when a sketch is active

[rcarmo]

It's not, I think. I split those out into two separate calls but didn't update the comments... Can you see it in the selection buffer?

[hlorus]

Yes i still see the black square in the selection buffer when a sketch is active

[rcarmo]

The latest push should fix that. I made the logic a bit more explicit. But I still need to go back and validate that overlapping selections work and hoist a few more constants.

[rcarmo]

Ok, this took a while, but I can now cycle through overlapping lines by double-clicking on them. Lines in the selection stack cycle through a similar color for now, as I don't have more time today, but would appreciate it if you could test this on your end and check if the behavior works for you...

[hlorus]

The behavior seems to work in a case where two lines intersect like on your picture but i cannot get it to work with parallel overlapping edges like in the picture below.
Also it seems that it does not respect the selection mode since on double-click the first line should be deselected again such that there's always just one line selected at a time.

[rcarmo]

Hmmm. OK. I think I know why. I need to check if double clicking is being properly propagated as well, but that test case should help. Will see if I can spend a couple of hours this week on it.