cone geometry

[Tristan Croll]

Trivial thing really. In chimerax.core.surface.shapes, line 190, the normals for the cone base are pointing in the wrong direction. The line should read:

        narray[nc2:] = (0,0,1) if points_up else (0,0,-1)

Oh, and the docstring for the cone_geometry function needs updating. It's no longer true that the point of the cone is at the origin - the origin is halfway along the cone axis.

[Tom Goddard]

The original code looks correct to me. It is setting the normal vector for the base end cap of the cone. If the cone points up, then the base normal points down (0,0,-1). Also I use this for VR and I believe it is correctly lit. Let me know if I am missing something.

[Tristan Croll]

On my machine, with a cone generated using the existing code the base is dark and out of step with the surroundings when facing the camera. When I flip the normal, it comes out looking bright. Will check again more closely today.

[Tristan Croll]

If I change cone_geometry to read:

def cone_geometry(radius = 1, height = 1, nc = 20, caps = True, points_up = True, flipped_normal = False):
   ...
        if flipped_normal:
            narray[nc2:] = (0,0,1) if points_up else (0,0,-1)
        else:
            narray[nc2:] = (0,0,-1) if points_up else (0,0,1)

... then the attached image has the result of flipped_normal = True on the right, False on the left, and a standard sphere in the middle for comparison.

[Tom Goddard]

Fixed.

The problem was that the cone base triangles had the wrong vertex order (needs to be counter-clockwise when looked at the outside face of the triangle).