976936 - SnappyTree demo stops working since Firefox26

Status: RESOLVED INVALID

(Web Compatibility :: Site Reports, defect)

Description

[Alice0775 White]

The demo stops working since Firefox26

STR
https://developer.mozilla.org/en-US/demos/detail/snappytree/launch

Actual Results:
No Tree

Comment 1

[Alice0775 White]

Regression window(m-i)
Good:
http://hg.mozilla.org/integration/mozilla-inbound/rev/2be3551a5d80
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:26.0) Gecko/20100101 Firefox/26.0 ID:20130906171346
Bad:
http://hg.mozilla.org/integration/mozilla-inbound/rev/356866ae2f68
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:26.0) Gecko/20100101 Firefox/26.0 ID:20130906172546
Pushlog:
http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=2be3551a5d80&tochange=356866ae2f68

Regressed by:
356866ae2f68	Jeff Gilbert — Bug 883478 - Update ANGLE to pull from 13-08-02. r=upstream,bjacob,bas

Comment 2

[Kelsey Gilbert [:jgilbert]]

From the console:

Error: WebGL: linkProgram failed, with this log:
Precisions for uniform projection do not match between the vertex and fragment shader

"GLGE error: Couldn't link shader: Precisions for uniform projection do not match between the vertex and fragment shader
"
Error: WebGL: linkProgram failed, with this log:
Precisions for uniform projection do not match between the vertex and fragment shader

 
"GLGE error: Couldn't link shader: Precisions for uniform projection do not match between the vertex and fragment shader
" 
Error: WebGL: useProgram: program was not linked successfully

Comment 3

[Kelsey Gilbert [:jgilbert]]

This makes this very likely to be an issue with the demo, where the demo is no longer considered spec-compliant WebGL, and thus us not rendering it as intended is the correct behavior.

This should be more fully inspected before we close it, but I strongly suspect this is the issue.

Comment 5

[Alice0775 White]

IE11 works as expected !

Comment 6

[Kelsey Gilbert [:jgilbert]]

This is a problem with the site, not our implementation. We can reach out to them to try to get them to fix it, but it violates this section of the GLES SL spec:

When the vertex and fragment shaders are linked together, then they will share a single global uniform
name space. Hence, types and precisions of uniforms with the same name must match across all shaders
that are linked into a single executable.

An error regarding mismatched precisions for a uniform is generated in newer versions of both Firefox and Chrome. I checked the shader sources manually:

gl = document.getElementByTagName('canvas')[0];
vs = gl.programCache[2].vShader; // This is attached to `gl` by the app.
fs = gl.programCache[2].fShader;

Using gl.getShaderSource() on `vs` and `fs` shows that `fs` uses `precision mediump float`, while `vs` doesn't, and since the decls for the shared uniforms (like `projection`) are not set to the same precision manually, they inherit the default precision for `float`. Default precision for `float` in vertex shaders is `highp`, and the default for the fragment shader here was set to mediump. Thus, the precision for (at least) `projection` doesn't match when the app tries to link the vertex and fragment shaders.

Failing to link such a shader is required by the spec. IE is out-of-spec in this regard.

Comment 7

[Masatoshi Kimura [:emk]]

Morphing this to an evangelism bug.

Comment 8

[Hallvord R. M. Steen [:hallvors]]

Well, I'm sure we can find someone to reach out to..
Is there a Bugzilla project for dev.mo ? Just moving the bug there might work too.

Comment 9

[Mike Taylor [:miketaylr]]

I don't have any issues with the demo in Aurora (nor errors in the console) on OSX. Perhaps this was already updated?

Comment 10

[Hallvord R. M. Steen [:hallvors]]

Seems broken here. Same errors in console, even in nightly.
We can try complaining here: https://github.com/supereggbert/SnappyTree/ but it doesn't seem to be maintained.

Comment 11

[Mike Taylor [:miketaylr]]

I don't see that demo on MDN anymore. Let's close.