mrdoob/three.js — Issue #1097: Viewport setting fails for some heights with Chrome ANGLE
Author: alteredq
Created: 2012-01-13 02:14:33+00:00
State: open

Since some time I started to notice postprocessing example getting broken, occasionally showing upper left quadrant image blown to the full window size with only upper right quadrant being overlaid over this full-sized subimage.

![viewport bug](http://alteredqualia.com/tmp/img/viewport_bug.png)

http://mrdoob.github.com/three.js/examples/webgl_postprocessing.html

Upon some digging problem seems to come from this line:

https://github.com/mrdoob/three.js/blob/master/examples/webgl_postprocessing.html#L405

It looks like for some viewport heights / y-coordinates viewport parameters are just ignored and instead viewport is set to be full window.

Width doesn't seem to suffer from this bug.

With OpenGL renderer there is no such behavior, everything is ok.

Bug appears on both Nvidia and ATI GPUs so it seems like something coming from ANGLE itself (as opposed to driver issue).