WebGL support - Bokeh Discourse

_jmApr 21, 2021 #1

QUESTION … Is the bokeh documentation around WebGL acceleration up-to-date w.r.t. the glyphs that benefit from it? Or is there support for line-like glyphs such as segment and multiline?

The bokeh documentation lists which glyphs benefit from WebGL acceleration support and specific list line().

https://docs.bokeh.org/en/latest/docs/user_guide/webgl.html

There is an old GitHub issue where some discussion in the thread mentions adding WebGL support for multiline but it’s not clear if that was aspirational or actually done.

github.com/bokeh/bokeh

Drawing many Line glyphs with webgl enabled gives bad performance

opened 11:04PM - 26 Jul 16 UTC

canavandl

type: discussion tag: webgl

Code to reproduce: ``` python import numpy as np from bokeh.plotting import out…put_file, show, figure output_file('line.html') webgl = True plot = figure(title='WebGL = {}'.format(webgl), webgl=webgl) for i in range(50): data = np.random.rand(2,10) plot.line(x=data[0], y=data[1]) show(plot) ``` It appears that drawing many Line glyphs (very noticeable above 50) with webgl=True causes poor rendering performance (~5 second page render). Using the Chrome profiler dev tool, it appears that many CPU cycles are spent inside of core webgl calls (`getProgramParameter` and `getShaderParameter`). <img width="1434" alt="screen shot 2016-07-26 at 5 56 31 pm" src="https://cloud.githubusercontent.com/assets/2198981/17158273/d8a4da8a-535a-11e6-9612-e29fab0eb3a8.png"> Here's the profiler output with webgl disabled: <img width="1437" alt="screen shot 2016-07-26 at 5 56 44 pm" src="https://cloud.githubusercontent.com/assets/2198981/17158282/e7843460-535a-11e6-86ac-40701f1c7ddc.png"> It's worth discussing if these webgl calls could potentially be aggregated into fewer calls or cached.

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Ian_ThomasApr 21, 2021 #2

@_jm A major rewrite of the WebGL code began a couple of months ago and we plan to continue it to cover many more glyph classes. The only glyphs currently supported are line, rect, circle and all of the scatter/marker glyphs. None of these are fully functional yet though (e.g. some of dashed line options) and we have been concentrating on accuracy more than speed at this stage. We expect to make big advances over the next few months in terms of accuracy, performance, and coverage of glyph classes.

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