Wednesday, January 30, 2013

[android-developers] Re: glGetShaderPrecisionFormat

Okay.  In all honesty, I'm not 100% sure what the 33 and 13 actually mean.

Especially the latter one, the precision.  The docs say:

precision
Specifies a pointer to the location in which the log2 of the precision of the format is returned.


So, if that number is the log2 of the precision, the precision must be 2^13, which is 8192.

So, yeah, I don't really know what that number represents.





On Wednesday, January 30, 2013 2:38:21 PM UTC-6, RichardC wrote:
Those number look correct.  High Precision support is NOT required to be implemented in the fragment shader and if your implementation does not support high precision you will get 0s from the glGetShaderPrecisionFormat query.

On Wednesday, January 30, 2013 8:32:43 PM UTC, bob wrote:
Oh, ok.  Thanks.

It works if I do this:

GLES20.glGetShaderPrecisionFormat(GLES20.GL_FRAGMENT_SHADER, GLES20.GL_MEDIUM_FLOAT, range, 0, precision, 0);

range = [33, 33]
precision = [13]



On Wednesday, January 30, 2013 2:27:26 PM UTC-6, RichardC wrote:
0 means precision format is not supported

"If a high precision floating-point format is not supported for fragment shaders, calling glGetShaderPrecisionFormat with argumentsGL_FRAGMENT_SHADER and GL_HIGH_FLOAT will return 0 for both range and precision. Support for a high precision floating-point format is mandatory for vertex shaders."

From:
http://www.khronos.org/opengles/sdk/docs/man/xhtml/glGetShaderPrecisionFormat.xml

On Wednesday, January 30, 2013 8:22:30 PM UTC, bob wrote:
I tried to call the function glGetShaderPrecisionFormat like so:

int range[] = new int[2];
int precision[] =  new int[1];
GLES20.glGetShaderPrecisionFormat(GLES20.GL_FRAGMENT_SHADER, GLES20.GL_HIGH_FLOAT, range, 0, precision, 0);

However, it seems to just stick zeros into range and precision.  Or it just never filled them in.

Anyone know about this?

Thanks.

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