Feature/wireframe

[SridharJagannathan]

Updated for #421
@jefferis:

1. Along with this implementation I have also fixed a bug in commit 3cf85f0
   which can be reproduced as follows:

nclear3d()
plot3d(Cell07PNs[[2]],col='blue',add=FALSE)

2. For the wireframe implementation, I have made a new function wire3d that masks the function with the same name from rgl and will pass the call to either rgl or plotly dependent on the option of nat.plotengine.
3. Currently works for triangle meshes but the approach can be easily extended for quad meshes as well.

[coveralls]

Coverage increased (+0.1%) to 83.45% when pulling 8933f6d on feature/wireframe into 6c7f844 on master.

[SridharJagannathan]

Hi @SridharJagannathan, I see the problem, but that's not the solution. The bug is here:

nat/R/neuron-plot.R

Lines 65 to 66 in 3cf85f0

	if (!add)
	nclear3d(plotengine)

That should have read:

nclear3d(plotengine=plotengine)

@jefferis Thanks for this, I see your point, isn't it usually the convention that when a function has one formal argument, followed by ellipsis, people usually can supply that argument without naming them, or to frame it better which is usually preferred,
nclear3d <- function(plotengine = getOption('nat.plotengine'),...) where people can simply use nclear3d(plotengine)
or
nclear3d <- function(...,plotengine = getOption('nat.plotengine'))

[jefferis]

It's because nclear3d is actually a wrapper around rgl::clear3d and most of the time you don't need to touch the plotengine argument because the default value works fine. You see examples of ellipsis first where the subsequent arguments are options rather than the main deal. c() is an example of this.

[SridharJagannathan]

Things that still need to be done:

• Support for quad mesh types
• Support for argument add=TRUE
• Test case for mesh properties
• Test case for wire3d.shapelist3d

[SridharJagannathan]

@jefferis: I have updated all the comments per our discussion, please review this and merge the same.

[jefferis]

should be add=TRUE to be consistent with current usage (where wire3d doesn't clear the plot)

[jefferis]

Thank you!