topic Re: Backface cull for editable splines in 3ds Max Modeling Forum

Backface cull for editable splines

Anonymous — Mon, 05 Jul 2021 12:25:38 GMT

Hey

I'm using drawings imported from AutoCAD as references for modelling a building. So all the views and sections are placed around the floor plan.

when I use planes with textures I can turn on backface cull on them so from whichever view I'm looking the plande which is turned back to me is invisible and I can draw according to the reference "on the other side" of the floor plan.

Is there a way to do something similar with editable splines? Backface cull doesn't work on splined unfortunately. Maybe there is some helper\technical material?

I also though about using some kind of clipping like in camera but I don't know how to do it for regular views (left, right , etc. )

Re: Backface cull for editable splines

RobH2 — Sat, 10 Jul 2021 02:07:34 GMT

I don't believe what you are thinking about is possible. 'Backface Cull' works because a polygon has a normal vector. If the vector is towards the camera it is visible, of not, it's invisible (if culling is enabled).

Splines don't have normals. They are just lines connected to points with x,y,x coordinates in space. A spline is just a mathematical representation of a connecting line between two points. There is not front or back or normal. It's just a line with endpoints.

You can use 'Viewport Clipping' in a viewport to limit what's visible and it will work on any kind of element but it's just clipping the z-depth of the view. It's not smart, it's kind of like depth of field except it 'clips.'

So, I don't believe you can cull splines the way you are describing.

Re: Backface cull for editable splines

domo.spaji — Sat, 10 Jul 2021 17:56:06 GMT

It is working same as other mesh objects.

Whatever you do to see it in view it become a mesh with faces, normals... (like enable in viewport)

If you want to disable "wireframe" from back side on it in shaded view, assign some mesh-turning modifier (like mesh select, UVW map...), set mod. to "Off in renderer" and obj. to backface cool.

That's for closed, non-overlaping splines, for others don't need backface cool - those will disappear.

Re: Backface cull for editable splines

Anonymous — Tue, 13 Jul 2021 09:13:09 GMT

Thanks. I did it with backface cull.

Re: Backface cull for editable splines

Anonymous — Tue, 13 Jul 2021 09:13:29 GMT

Thanks for hint. Will check it out.