[of-dev] ofTexture and glDataType

Memo Akten memo at memo.tv
Thu Apr 14 09:16:31 PDT 2011


You can create a 16bit float rgba texture (half precision floats) by
passing GL_RGBA16F_ARB to ofTexture. When filling it you can pass an array
of normal 32bit floats. I"ve never had to readback from these, but as far as
I know you can have it converted to 32bit on the read back.

2011/4/14 Elliot Woods <elliot at kimchiandchips.com>

> how are the 16bit floats defined? custom type?
>
>
> On 15 April 2011 00:58, Memo Akten <memo at memo.tv> wrote:
>
>> Yea this always concerned me too! I added the switch statement a while ago
>> because I needed float textures. Before the switch it was hardcoded to
>> luminance+unsigned byte. So when I added the switch+float textures, I didn't
>> want to change the default in case it broke some existing apps.
>>
>> The 3rd parameter is a hint, so like golan says the implementation
>> (drivers) decides what to do and picks the most suitable format.
>>
>> Moving forward I'd vote for ofImage (and ofPixels) to support float
>> textures too. I think we could do with a generic imageFormat class/struct
>> which stores info on all relevant info of an image - but ideally it should
>> be able to support float, and half-float (crucial when dealing with fast fbo
>> based stuff). And then ofTexture, ofPixels and ofImage can all read from
>> this format struct and do everything accordingly.
>>
>>
>>
>> On 14 April 2011 16:38, Golan Levin <golan at flong.com> wrote:
>>
>>> "fortunately, the fact that this works means, i think, that GL is always
>>> storing colors as 4 bytes regardless of whether you tell it GL_LUMINANCE or
>>> GL_RGB, otherwise we would have seen this sooner..."
>>>
>>> I believe this is graphics-card (i.e. implementation) dependent.
>>> g
>>>
>>> On Thu, Apr 14, 2011 at 10:39 AM, Kyle McDonald <kyle at kylemcdonald.net>wrote:
>>>
>>>> i just wanted to bring this to the attention of the more advanced
>>>> users here on the dev list:
>>>>
>>>> http://forum.openframeworks.cc/index.php/topic,5955.0.html
>>>>
>>>> tl;dr: there is a really weird ambiguity hidden deep in the heart of
>>>> OF that has never made sense to me,
>>>> and now that i've looked closer i think something must be wrong and
>>>> should be addressed.
>>>>
>>>> <3
>>>> kyle
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>>>
>>>
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>>
>>
>> --
>> Memo Akten
>>
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>>
>>
>>
>>
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>
>
> --
> Elliot Woods
>
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-- 
Memo Akten

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