Add :mesh3d series type for Plotly

[dwd31415]

This pull-request adds the possibility to plot arbitrary 3d meshes using the mesh3d plot type in Plotly. It can be seen as partial fix/implementation for #392. For backends other than Plotly there is a fallback recipe provided that however does not support specifying the triangles of the mesh.

Example:

using Plots; plotly()

x=[0, 1, 2, 0]
y=[0, 0, 1, 2]
z=[2, 4, 2, 3]

i=[0, 0, 0, 1]
j=[1, 2, 3, 2]
k=[2, 3, 1, 3]

plot(x,y,z,seriestype=:mesh3d;i,j,k)

Output:

[BeastyBlacksmith]

Hello Adrian,
thanks for this contribution. That is a really good feature and a worthwhile addition to Plots.jl.

There are some things we need to adjust. Firstly, the API is not really in line with what Plots usually does and i, j, k are hard to discover keywords. So I would suggest we add a new series keyword connections (better names welcome) and pass a tuple of vectors like

mesh3d(x, y, z, connections = (i, j, k))

In the future we then could also support vectors of tuples and matrices.

Secondly it would be good to have an example in the examples file, so this gets added to the tests and shows up in the documentation and there should also be an explanation of what the values of i, j and k actually refer to.

[dwd31415]

Hi Simon,
thanks for the feedback.

Regarding the first point that sounds like a much cleaner interface. Am I right that adding connection as a series keyword would be achieved by adding it to _series_defaults in args.jl? It seems to work but I just wanted to check it is not some kind of hacky way.

[BeastyBlacksmith]

Am I right that adding connection as a series keyword would be achieved by adding it to _series_defaults in args.jl? It seems to work but I just wanted to check it is not some kind of hacky way.

You are right. That is the way to go.

[BeastyBlacksmith]

This should be the last round of changes and its mainly cosmetics

[dwd31415]

Okay great, then everything should be fine now.

[BeastyBlacksmith]

Thanks!

[dlfivefifty]

Does this support setting the colours of the triangle? Trying to plot a function a sphere: have the sphere working but now need the colours

[dwd31415]

No I don't think this is supported. As a hacky workaround you could plot the triangles individually since you can specify the color of the whole mesh like this mesh3d(x,y,z;color=:purple,connections=(i,j,k))

[dlfivefifty]

That's too bad... I'm guessing the Plotly backend supports it?