harshkhandeparkar
commented
3 years ago https://tc39.es/ecma262/#sec-math.atan2
The spec for atan2 is pretty sophisticated and long... Does GLSL have an atan2 already?
Open danbgoldman opened 3 years ago
harshkhandeparkar
commented
3 years ago https://tc39.es/ecma262/#sec-math.atan2
The spec for atan2 is pretty sophisticated and long... Does GLSL have an atan2 already?
danbgoldman
commented
3 years ago IIUC, GLSL atan is overloaded to take both 1 argument (like Math.atan) and 2 arguments (like Math.atan2). AFAIK the second implementation is identical to C/javascript.
https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/atan.xhtml
ted-piotrowski
commented
3 years ago Can confirm that pull request fixes supplied repro case.
What is wrong?
atan2 should return values from -pi to pi, but instead returns values from -pi/2 to pi/2 in gpu mode. It also returns undefined results for x=0.
Where does it happen?
In Chrome browser.
How do we replicate the issue?
I'm attaching a repro case - correct behavior can be seen in mode:cpu, incorrect behavior in mode:gpu.
atan2-bug.zip
How important is this (1-5)?
3 - I can work around, but also should be an easy fix.
Expected behavior (i.e. solution)
The backend GLSL implementations of atan2 use the single-argument version of atan(y_over_x), instead of the two-argument version atan(y, x).