Fix for wireframe rendering (issue 8729)

[ikerr]

This commit fixes wireframe rendering when groups and drawRange are in use.

I removed calls to checkEdge() in getWireframeAttribute() to ensure that the number of wireframe indices is exactly twice the number of non-wireframe indices. This makes it simple to adjust the group and drawRange start/end indices in WebGLRenderer.

#8729

[mrdoob]

Indeed. Better to go simpler here.

[mrdoob]

Thanks!

[ikerr]

No prob, thanks for the quick turnaround!

[mrdoob]

I think this is the right code though?

var rangeStart = geometry.drawRange.start * rangeFactor;
var rangeCount = geometry.drawRange.count * rangeFactor;

var groupStart = group !== null ? group.start * rangeFactor : 0;
var groupCount = group !== null ? group.count * rangeFactor : Infinity;

var drawStart = Math.max( rangeStart, groupStart );
var drawEnd = Math.min( dataCount, rangeStart + rangeCount, groupStart + groupCount ) - 1;

[ikerr]

Yes, I think you're right. I'll update my branch.