Is it able to set object properties?

[PikaPei]

For example, I have a LineSegments object and want to change its color or linewidth. I know I can create a new object to cover it currently, but it's not suitable for animation. Could I use these kinds of command to accomplish it?

setprop!(vis[:linesegment], "color", [1., 0., 0., 1.])
setprop!(vis[:linesegment], "material", LineBasicMaterial(linewidth=3))

Thank you!

[PikaPei]

Hello, sorry for bothering you. I'm new to both JavaScript and Three.js. I just want to know whether it's possible to test MeshCat by myself? I assume that I could edit index.js in path: [@DIR, "..", "assets", "meshcat", "src"], for example, add console.log("test");. But nothing happened. Is it because the corresponding codes had been generated already?

[rdeits]

Hi--no, I'm afraid it's not currently possible, but I think we could do it. The setprop! commands currently can only change properties of the threejs Object itself (things like quaternion, scale, position, visible, etc.), while the color of the material is inside object.material.color.r, object.material.color.g, etc.

If you are interested in changing MeshCat yourself, I would suggest that you do:

1. In Julia, do MeshCat.develop_meshcat_assets() which will clone https://github.com/rdeits/meshcat into MeshCat.jl/assets/meshcat for easier development.
2. Follow the development instructions from https://github.com/rdeits/meshcat#developing-meshcat to set up all of the javascript dependencies.

The reason that just editing the source files doesn't work is that the javascript sources need to be combined with the three.js sources into a single bundle (you can find this bundle in MeshCat.jl/assets/meshcat/dist/main.js and main.min.js if you are curious). Don't edit the main.js or main.min.js file by hand: it will be overwritten when you run npm run build. Instead, edit meshcat/src/index.js and run npm run build as described in https://github.com/rdeits/meshcat#developing-meshcat

[PikaPei]

Oh, sorry, I did't notice that developing part. Thanks for your kind reply, I'll give it a try!

[mfogelson]

Was there any progress on this?

[ferrolho]

You can work around this issue by creating multiple instances of your object, each with its own material property. Then, you can enable the correct instance at the right frame to render smooth animations.

Here's an example:

using Colors
using MeshCat

vis = Visualizer()
open(vis)

points = [rand(3) for _ = 1:100]
pointcloud = PointCloud(points)

for i = 1:255
    material = LineBasicMaterial(color=RGB(i/255, (255-i)/255, 0.1), linewidth=2)
    setobject!(vis["line_$(i)"], Object(pointcloud, material, "Line"))
end

function hide_all_lines()
    for i = 1:255
        setvisible!(vis["line_$(i)"], false)
    end
end

anim = MeshCat.Animation()

for i = 1:255
    atframe(anim, i) do
        hide_all_lines()
        setvisible!(vis["line_$(i)"], true)
    end
end

setanimation!(vis, anim)

https://github.com/rdeits/MeshCat.jl/assets/4166093/10b48fa7-4ad5-47db-b762-db0e9249c04b