Three.js: Support vector field plots

[paulmasson]

This enhancement allows plotting of 3D vector fields. This is done by replacing the translated line segments of the field with 3D arrows at half the thickness of the lines. Since there is currently no way to turn off the arrow heads on the vector field, it is assumed they will be present.

CC: @egourgoulhon

Component: graphics

Keywords: threejs

Author: Paul Masson

Branch/Commit: 057bba5

Reviewer: Eric Gourgoulhon

Issue created by migration from https://trac.sagemath.org/ticket/27932

[paulmasson]

Branch: u/paulmasson/vector-field

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

58d6b55

Cleanup

[sagetrac-git]

Commit: 58d6b55

[paulmasson]

comment:3

In the process of adding this enhancement, I discovered that line3d has an option arrow_head for adding such to line segments that is not currently supported by the Three.js viewer. Since I'll assume most people will use arrow3d to achieve the same effect, I don't plan to support that attribute unless necessary.

[egourgoulhon]

comment:6

Thanks for this improvement! The following example from the Plotting 3D fields section of the reference manual:

x,y,z = var('x y z')
g = plot_vector_field3d((x*cos(z),-y*cos(z),sin(z)), (x,0,pi), (y,0,pi), 
                        (z,0,pi))
show(g, viewer='threejs')

works but

x,y,z = var('x y z')
plot_vector_field3d((x*cos(z),-y*cos(z),sin(z)), (x,0,pi), (y,0,pi), (z,0,pi), 
                    viewer='threejs')

results in a Jmol plot, as if the option viewer='threejs' was not taken into account...

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

057bba5

Set extra keywords

[sagetrac-git]

Changed commit from 58d6b55 to 057bba5

[paulmasson]

comment:8

Those pesky extra keywords...

[egourgoulhon]

comment:9

Thanks!

[egourgoulhon]

Reviewer: Eric Gourgoulhon

[vbraun]

Changed branch from u/paulmasson/vector-field to 057bba5

[embray]

comment:12

Not in Sage 8.8. Let's please to try keep tickets' milestones related to the release in which we actually intend to include them, and in particular the release in which they were actually included, especially when closing tickets.