[GEM-dev] vertex displacement

cyrille henry cyrille.henry at la-kitchen.fr
Sun Dec 9 23:42:27 CET 2007



marius schebella a écrit :
> I did not see the the newWave before, but now I understand it and it 
> makes sense to me...
> the performance says dsp ~22%(with newWave 60). with newWave 100: 30% 
> and with newWave 256: ~65-70%. is that what you expected?
i would expect less.
is it the same with all contiguration (A,B,C)?

on my computer, it use 80% cpu with newWave 60...

cyrille

> I also added some factor to the R G and B values, which looks nice.
> marius.
> 
> cyrille henry wrote:
>>
>>
>> marius schebella a écrit :
>>> hello cyrille,
>>> I did not know that this was possible at all. I always thought there 
>>> are only 4 vertices involved in the primitive and now I see that it 
>>> is possible to do displacement on pixel basis.
>> well. ther is only 4 vertices on a square. that is why i use a newWave 
>> primitive.
>> displacement is made on every evrtice of this primitive.
>> but the displacement factor comme from a texture.
>>
>>> I tested the patch and on my system (osx, ATY,RadeonX1600) I can use
>>> A 0, C 0, K 1 (B 1 or 0 does not make a difference)
>>> A 1, C 1, K 1 (B - no difference)
>>> and also your combinations with 256, 0.00390625.
>>> so for me it works just fine.
>> great!
>> can you have a look at the performance.
>>
>> for me, when it work it's very ineficient....
>> but it should be very fast.
>> (you can by exemple add more vertice on the primitive)
>>
>>
>>> the differences may be related to different hardware/os.
>> yep. i'm on linux/nvidia
>>
>> could someone else try this patch on diferents system?
>>> I also don't need the line
>>> #extension GL_ARB_texture_rectangle : enable
>> in fact, if i remove it, i have a warning at the shader compilation, 
>> but it also work.
>>
>>> what do you mean with "using texture in vertex shader would be great..."
>> i mean that i would be happy if i could make this patch to work just 
>> like in your computer.
>>
>>> do you think this should work without gemframebuffer?
>> no. in fact, using texture in the vertex shader is efficient only when 
>> using 32 bit texture, and this on only possible with framebuffer.
>> see chris mail on this list for more details.
>>
>> cyrille
>>
>>> marius.
>>>
>>> cyrille henry wrote:
>>>> hello,
>>>>
>>>> i investigate a bit more the vertex displacement problem.
>>>> so i've got a 8 bit texture that is rendered in a FLOAT framebuffer, 
>>>> in order to convert it to 32 bit.
>>>> then, the frambuffer texture is used in a shader to distord a primitive
>>>>
>>>> i have to strangely mix mode 0 and mode 1 in the patch to make it 
>>>> work, and this is very ineficient (just like in 8bit mode).
>>>>
>>>> framebuffer and fragment shader usually work in mode 0 and 1 on my 
>>>> computer.
>>>>
>>>> see patch for more.
>>>>
>>>> thanks to have a look.
>>>> using texture in vertex shader would be great...
>>>>
>>>> thanks
>>>> Cyrille
>>>>
>>>>
>>>>
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>>
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