ANGLE_instanced_arrays produces garbage vertex data when there are more instances than vertices and non-overlapping parts of buffers are updated.

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Load the attached HTML with ANGLE and ANGLE_instanced_arrays 
implemented/enabled

What is the expected output? What do you see instead?
Expected: Four green boxes with varied red and green borders.
Actual: Two green boxes with red and green borders on the left, two boxes with 
randomly changing colors on the right.

What version of the product are you using? On what operating system?
Chrome Canary with WebGL draft extensions enabled on Windows 7.

Please provide any additional information below.

If you have V vertices per instance an I instances, the first V instances draw 
correctly. Only instances V-I have garbage data. The garbage data is only 
introduced if your instanced data is in a buffer that is larger than it needs 
to be and you upload some other data to a non-overlapping part of that buffer 
after your first draw.

Original issue reported on code.google.com by bcorn...@google.com on 22 Aug 2013 at 12:06

Attachments:

• testangleinstancing.html

[GoogleCodeExporter]

Could we please prioritize investigating and fixing this bug? It will prevent 
Google Maps from using instancing on Windows. Thanks.

Original comment by kbr@chromium.org on 23 Aug 2013 at 11:34

• Added labels: Priority-High
• Removed labels: Priority-Medium

[GoogleCodeExporter]

Code review URL:

https://codereview.appspot.com/12937045

Original comment by jmad...@chromium.org on 26 Aug 2013 at 12:55

• Changed state: Review

[GoogleCodeExporter]

geofflang: peer review please

Original comment by shannonw...@google.com on 26 Aug 2013 at 2:31

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Original comment by shannonw...@google.com on 26 Aug 2013 at 2:56

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Original comment by shannonw...@google.com on 26 Aug 2013 at 6:57

[GoogleCodeExporter]

Applied to the master and es3proto branches -- the legacy branch still has some 
rendering issues.

Original comment by jmad...@chromium.org on 26 Aug 2013 at 10:55

• Changed state: Fixed