circular arcs in coin3d

[Joel_graff]

Trying to sort out circular arcs at the scene graph level. I've been stepping through the FreeCAD codebase looking to see if I can find some clues on how to do it, but have come up empty. I suspect I'm just looking in the wrong place or for the wrong thing...

Anyway, I can see from the coin3D docs there's no direct support for circular arc generation - it appears all curves must be expressed as splines. Is there any support written to provide circles / circular arcs in coin3D so I don't have to try to sort out approximating them?

[ickby]

OpenGL cannot do arcs or any curved geometry. It ist all triangles and Line Segments. So that is basically what you need to go for and approximate a circle to line segments. The coin spline classes do the same, and I don't think it would be useful to approximate a circle with a spline to be approximated by lines.

[Joel_graff]

I don't think it would be useful to approximate a circle with a spline to be approximated by lines.

That was my initial thought as well, but the problem is, every time I have to refresh the scene graph, I have to recompute the coordinates of the discretized arc and update the graph - which means spending a lot of time doing math in Python. Hence my half-hearted hope there was a built-in FreeCAD library call or something similar that could generate an arc, either as a line set or spline in C++.

Otherwise, I can to generate an arc as an edge object, discretize it, and use that to update scenegraph coordinate, but I somehow doubt that's going to be better than optimized Python code...