Error running saveSVG.js example on Ubuntu on version 6.0.1

[lobis]

Hello,

I am running into an error when I run the saveSVG.js example on a Ubuntu 20.04 host. The example runs OK for me in my windows machine. (both are using node 15).

me@host:~/share/github/radiation-transport-visualization/geometry-browser/node$ node saveSVG.js
JSROOT version 6.0.1 1/03/2021
length of data = 47513
length of dezipped =883215
making SVG
Reuse existing d3.js version 6.6.2, expected 6.1.1
Creating clones 420 takes 4 uniquevis 334
THREE.WebGLRenderer: Cannot read property 'getShaderPrecisionFormat' of undefined
/mnt/c/WSL-Ubuntu-20.04/github/radiation-transport-visualization/geometry-browser/node/node_modules/three/build/three.js:17284
                        if (_gl.getShaderPrecisionFormat === undefined) {
                                ^

TypeError: Cannot read property 'getShaderPrecisionFormat' of undefined
    at new WebGLRenderer (/mnt/c/WSL-Ubuntu-20.04/github/radiation-transport-visualization/geometry-browser/node/node_modules/three/build/three.js:17284:12)
    at Object.jsrp.createRender3D (/mnt/c/WSL-Ubuntu-20.04/github/radiation-transport-visualization/geometry-browser/node/node_modules/jsroot/scripts/JSRoot.base3d.js:318:21)
    at TGeoPainter.createScene (/mnt/c/WSL-Ubuntu-20.04/github/radiation-transport-visualization/geometry-browser/node/node_modules/jsroot/scripts/JSRoot.geom.js:1978:29)
    at TGeoPainter.prepareObjectDraw (/mnt/c/WSL-Ubuntu-20.04/github/radiation-transport-visualization/geometry-browser/node/node_modules/jsroot/scripts/JSRoot.geom.js:3087:25)
    at /mnt/c/WSL-Ubuntu-20.04/github/radiation-transport-visualization/geometry-browser/node/node_modules/jsroot/scripts/JSRoot.geom.js:4139:78

You can reproduce this on a docker container as follows (I demonstrate it for node 12, but would also fail for 15, but I don't use 15 since additional dependencies are requiered):

docker run -it ubuntu:latest

apt update
apt install -y curl git
curl -sL https://deb.nodesource.com/setup_12.x | bash -
apt install -y nodejs
node --version
npm install jsroot
git clone https://github.com/root-project/jsroot.git
cd jsroot/demo/node
node makesvg.js

After installing, the error is the following:

root@4eabd05dfaf8:/jsroot/demo/node# node makesvg.js                                                                                                                                                               JSROOT version 6.0.1 1/03/2021                                                                                                                                                                                     Reuse existing d3.js version 6.6.2, expected 6.1.1                                                                                                                                                                 THREE.WebGLRenderer: Cannot read property 'getShaderPrecisionFormat' of undefined                                                                                                                                  (node:4146) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'getShaderPrecisionFormat' of undefined                                                                                                  at new WebGLRenderer (/node_modules/three/build/three.js:17284:12)                                                                                                                                                 at Object.jsrp.createRender3D (/node_modules/jsroot/scripts/JSRoot.base3d.js:318:21)                                                                                                                               at TFramePainter.JSROOT.TFramePainter.create3DScene (/node_modules/jsroot/scripts/JSRoot.hist3d.js:190:28)                                                                                                         at TH2Painter.JSROOT.TH2Painter.draw3D (/node_modules/jsroot/scripts/JSRoot.hist3d.js:1510:18)                                                                                                                     at /node_modules/jsroot/scripts/JSRoot.hist.js:6483:55                                                                                                                                                             at processTicksAndRejections (internal/process/task_queues.js:97:5)                                                                                                                                            (node:4146) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)                                                                                                                                                                                                              (node:4146) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.        
root@4eabd05dfaf8:/jsroot/demo/node#  

[linev]

Yes, I can reproduce a problem.
It is missing DISPLAY variable.
JSROOT uses canvas module for 3D visualization and it requires display.
You can do following:

apt-get install xvfb
xvfb-run node makesvg.js

[linev]

I keep it open for a while.
I do not like that for running batch jobs one have to use X11 (or its emulator).
After 6.1 release I will upgrade three.js and also will try to find another solution here

[lobis]

Much better, thanks!

[linev]

After some investigation - seems to be headless-gl does not support real offscreen rendering and requires X11 running.
There is PR stackgl/headless-gl#116, which potentially should enable alternatives - but it is open for 4 years.
For the moment I see no other alternatives of using xvfb-run