[PD] RE : Re: need help with gem and glsl feedback

[Jack]

Test with this one.
You should get the motion blur on the torus (here from your webcam).
Ifnot, there is a broblem somewhere else...

Le 06/10/2013 22:13, Py Fave a écrit :
> Hello , i just opened your last patch and am looking at it .
> weanwhile i reply to your points
>
> 2013/10/6 Jack <jack at rybn.org>:
>> Hello,
>>
>> Le 05/10/2013 22:51, Py Fave a écrit :
>>
>> in fact my problem is not solved .
>> it seems like the feedback effect  happens everywhere but on the
>> surface drawn by the shader .
>>
>> According to the patch, the feedback is applied on a [square 4] (where there
>> is also the [torus 2]).
>> Then, [gemframebuffer] 'snap' the whole 'inside' [square 4]. And your torus
>> is inside this snapshot (as texels and not vertices).
>>
> yes ,and then there is  some feedback on the texels of the square .
> but in my patch if i rotate the torus i get some feedback but not on the
> shaded part (only the silhouette of the torus .  i don't know why .
> i would like everything to go in the feedback loop .
It should be OK if you put the shader for the torus on the Gem chain
with [gemhead 5] and then let the feedback chains safe like in the patch
attached.
Tell me if there is a problem now.
++

Jack


>
> in fact i try to have trails that show "geodesics" on a surface
> later i plan to replace my torus with other models .
>
>
>
>> i use a torus , in perspective wich has a shader applied .
>>
>> i tried the following workaround(archive is joined ) , but still no luck .
>> the file to open has a OPEN in name .
>>
>> It seems there is no circle4.geom, [receive13] and [nshader0]
>> objects/abstractions in your .zip.
> sorry i forgot  .
>
> receive13 only is missing .
> it's part of ext13 library (and is in pd-extended iirc)
> http://puredata.info/downloads/ext13
>
> [receive13 nothing ]could  be replaced by receive nShader1
> or all the shader abstraction can be replaced by the classical shader network
> with fragment shader = circle4.frag  and vertex shader = circle4.vert.
> no .geom was used
>
>
>> i would like the dots to have the feedback ,
>> or dots + geometry alltogether.
>>
>> I can't see dot in your patch (or gem window), maybe they come from geometry
>> shader (which is missing) ?
>>
> i didn't use geometry shader . just  fragment .
> glsl program complains in the abstraction  but no harm here i think
>
>> i tried pix_snap2tex ( using gems.feedback from pdmtl abstractions) too
>> but no luck because we can't choose the mixing function .
>> and i would like only white to make trails .
>> and i don't know how to keep the supporting geometry from appearing .
>> the torus should be full black with a white trail only .
>>
>> A simple possibility is to use 2 torus, a black 'on' a white. And use the
>> white for the trail ?
>>
>> An other way :
>>
>> white torus as texture
>> |__> in the feedback __> output feedback as texture
>> |__> convert white in black texel __> output black torus as texture
>>
>> Then mix (multiply) black torus with white feedback to get a black torus
>> with white trails.
>> ++
>>
>> Jack
>>
> i'll send a modified patch a bit later .
>
> Thank you so much i see some good things from the last patch you sent .
>
> it is not what i want to do but opens other directions
> and perhaps i was focusing on one method but there seems to be alternatives .
>
> i'll update this thread tomorrow .
> i have to keep some life away from computer :-)
>
> Thanks for your help
>
> Py
>
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// Jack/RYBN 2013
#extension GL_ARB_texture_rectangle : enable
uniform sampler2DRect MyTex1, MyTex2;

void main() {
	vec2 tex_coord = gl_FragCoord.st;
	vec4 color = texture2DRect(MyTex1, tex_coord);
	vec4 color0 = texture2DRect(MyTex2, tex_coord);
	color *= 0.01;
	color0 *= 0.99;
	gl_FragColor = color+color0;
 }