HLSL to GLSL atan2 Function

[toneburst]

Anyone know if there is a GLSL equivalent to HLSLs ‘atan2’ function?

alx

[NiCo1]

Just use atan(y,x), it’s the equivalent of atan2 in the range [-Pi,Pi].
atan(y/x) is in the range [-Pi/2,Pi/2].

N.

[toneburst]

Hi -NiCo-

thanks for getting back to me.
So, I just multiply the result of atan by 2.0 to get the same result as the HLSL atan2 function.

Cheers,

alx

[NiCo1]

@toneburst

So, I just multiply the result of atan by 2.0 to get the same result as the HLSL atan2 function

No,

HLSL atan2(x,y) == GLSL atan(y,x)

GLSL provides two atan-operators. One taking 1 parameter and one taking 2 parameters. The one with 2 parameters is the equivalent of atan2.

N.

[toneburst]

I see, thanks -NiCo-.
There must be some other reason my HLSL conversion isn’t producing the expected result then…

alx

[NiCo1]

That shouldn’t be hard to debug…
Make sure that you get the parameter ordering correct. In HLSL it’s (x,y) while in GLSL it’s (y,x)

N.

[toneburst]

Cheers -NiCo-!

Ah, yes, I did notice that. Thanks once again!
What I actually in my previous post was, there’s probably some other issues with the code, now that I have been able to eliminate the atan/atan2 issue, thanks to your advice.

alx