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0.7.6 live examples blank canvas in Chrome 5.0.375.99

#124

From Carl Witty at Carl.Witty@gmail.com

I was looking at your SceneJS "Live Examples" section, and none of the ones I tried worked under Google Chrome (version 5.0.375.99, for Linux, nvidia proprietary drivers). In particular, I tried the 4 examples in the first "Basic" section, and none of them worked.

All 4 did work in a copy of Firefox 4 beta 1 running on the same computer, and the Chrome browser does work for other WebGL demos on other sites (such as "Learning WebGL", among others).

The javascript console shows:

SceneJS V0.7.6 initialised
SceneJS.Scene config 'canvasId' unresolved - looking for default
canvas with ID 'scenejs-default-canvas'
Scene defined: s0
s0: Creating shader: 'scenejs-default-canvas;;;dirsddirsddirsd;;tff'
s0: Creating shader:
'_scenejs-default-canvas;;;dirsddirsddirsd;/uv/baseColor/multiply/anim;ttf'

(Perhaps you meant chrome's standard output? chrome does not print anything to stdout when loading the failing page.)

I just realized I didn't actually say what the failure mode was. The
problem is that the WebGL window shows up as pure black.

I'm using a mostly up-to-date installation of Debian testing,
including Debian's packaging of the nvidia drivers (package version
195.36.24-2).

From glxinfo:
OpenGL renderer string: GeForce 8600 GTS/PCI/SSE2
OpenGL version string: 3.2.0 NVIDIA 195.36.24

From cat /proc/cpuinfo:
model name : Intel(R) Xeon(R) CPU E5410 @ 2.33GHz
(that's basically the server version of a Core 2 Quad, I think).

I definitely did start chrome with "--enable-webgl"; for instance, I
can click back and forth between a tab showing
http://www.scenejs.org/ide.html?url=./examples/custom-geometry/cust...
(which does not work) and a tab showing http://learningwebgl.com/lessons/example01/ (which does work).

Reported by lindsay.kay (at xeolabs) · July 20th, 2010 @ 12:47 AM

State: resolved
Milestone: V0.7.7
Assigned to: lindsay.kay (at xeolabs) lindsay.kay (at xeolabs)

Activity

  1. Carl Witty
    Carl Witty

    I believe this problem was due to a bug in Chrome (I'm guessing http://code.google.com/p/chromium/issues/detail?id=40175). When I upgraded to the "unstable" branch of Chrome (version 6.0.466.0 dev), the problem went away.

    But I also tracked down the problem and found a workaround. I don't know if you're interested, but if so, here it is:

    gl.getActiveUniform was producing uniform names that had a trailing NUL. For instance, see this excerpt from the log:
    gl.getActiveUniform(program0, 0);
    var uniformLocation0 = gl.getUniformLocation(program0, 'uAmbient\u0000');
    gl.getActiveUniform(program0, 1);
    var uniformLocation1 = gl.getUniformLocation(program0, 'uLightColor0\u0000');
    The uniforms were then entered into the uniforms[] array under these names. Then, when you tried to look them up (in setUniform()) under the correct name, they weren't found.

    I produced a patch (attached) which fixed the problem for me in the old version of Chrome.

    (My first attempt didn't rename u.name to u_name; that didn't work. Evidently whatever kind of object u is silently ignores writes to .name .)

    If you do apply this patch (or a similar one), and want me to test it, let me know and I'll downgrade Chrome back to the buggy version to do the test.

    July 20th, 2010 @ 05:18 AM

  2. lindsay.kay (at xeolabs)
    lindsay.kay (at xeolabs)

    Nice one Carl, patch looks good.

    I'll apply that one tomorrow morning and get back to you.

    Thanks!

    July 20th, 2010 @ 05:39 AM

  3. lindsay.kay (at xeolabs)
    lindsay.kay (at xeolabs)
    • Milestone set to V0.7.7

    August 3rd, 2010 @ 11:52 PM

  4. lindsay.kay (at xeolabs)
    lindsay.kay (at xeolabs)
    • State changed from open to resolved

    August 3rd, 2010 @ 11:57 PM

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