Pierre Alexandre Tremblay

I am really seduced by the GPU processing, especially right now 

because I work on multimedia installations and want to free as much 

CPU for the audio part. It seems full of potential, but I find the 

learning curve quite steep. For example, the amazing examples by 

Andrew are so elegant, but there is lots of features in it I can't 

find in the documentation, for instance, the @capture that can save 

This is not a complain, but just a stucked poor coder who needs help 

to go further... What I do right now is designing the patch in Jitter 

matrix, then port is to slab. I know I will probably drop this 

approach quite soon, but my openGL licks are not near as my matrix 

I don't want to be given the patch, but I want to know where to find 

a good tutorial/reference for that whole world of openGl objects. Is 

there something I should read after the documentation to help me 

ps For example, I want to move around a jpeg right now, to use it as 

a mask on an incoming film. I manage to put my jpeg as a texture on 

a jot.gl.gridshape plane object, then position and resize my plane. 

But I have erasing problems, when the new size is smaller than the 

previous... we can see leftovers of the previous frame...

I am really seduced by the GPU processing, especially right now  
because I work on multimedia installations and want to free as much  
CPU for the audio part.  It seems full of potential, but I find the  
learning curve quite steep. For example, the amazing examples by  
Andrew are so elegant, but there is lots of features in it I can't  
find in the documentation, for instance, the @capture that can save  
my day.

This is not a complain, but just a stucked poor coder who needs help  
to go further... What I do right now is designing the patch in Jitter  
matrix, then port is to slab.  I know I will probably drop this  
approach quite soon, but my openGL licks are not near as my matrix  
knowledge.

I don't want to be given the patch, but I want to know where to find  
a good tutorial/reference for that whole world of openGl objects.  Is  
there something I should read after the documentation to help me  
design my really simple patches.

ps For example, I want to move around a jpeg right now, to use it as  
a mask on an incoming film.  I manage to put my jpeg as a texture on  
a jot.gl.gridshape plane object, then position and resize my plane.   
But I have erasing problems, when the new size is smaller than the  
previous... we can see leftovers of the previous frame...


slab-help

It's good to hear that you are interested in this. I strongly recommend 

grabbing a copy of the orange book, OpenGL Shading Language, by Randi J. 

Rost. You will want to pay special attention to the chapters 3,5, and 

16. I tend to keep this near my desk, and refer to it often.

The same could be said for the red book as well. This book goes a great 

distance in demystifying the OpenGL pipeline, and explains the more 

The important thing to remember with GLSL is that you are dealing with 

each pixel individually. A shader program doesn't have memory of its 

own. This can make them alternately very straightforward or very 

troublesome to implement. If you are having trouble implementing 

something specific, I encourage you to post to the list.

If there is any specific aspect of jitter and OpenGL that you feel could 

be explained in more detail, please let us know. I can always add it to 

Hi Pierre,
It's good to hear that you are interested in this.  I strongly recommend 
grabbing a copy of the orange book, OpenGL Shading Language, by Randi J. 
Rost.  You will want to pay special attention to the chapters 3,5, and 
16.  I tend to keep this near my desk, and refer to it often.

The same could be said for the red book as well.  This book goes a great 
distance in demystifying the OpenGL pipeline, and explains the more 
low-level jit.gl.sketch commands.

The important thing to remember with GLSL is that you are dealing with 
each pixel individually.  A shader program doesn't have memory of its 
own. This can make them alternately very straightforward or very 
troublesome to implement.  If you are having trouble implementing 
something specific, I encourage you to post to the list.

If there is any specific aspect of jitter and OpenGL that you feel could 
be explained in more detail, please let us know.  I can always add it to 
my agenda for weekly examples.

I have checked out your example too. It is a very nice patch on making use

of @capture and slab to generate effect out of a 3d geometry.

However, I am working on something I want to render a scene into texture and

use it in later rendering. I have been told of the "to_texture" message of

jit.render and have checked out the example in jitter tutorial. But I

still could not figure it all out and always produce error message,

"warning: method screen_grab called on invalid object".

Is it possible to have a more detailed example use of the message ?

I have checked out your example too. It is a very nice patch on making use
of @capture and slab to generate effect out of a 3d geometry.

However, I am working on something I want to render a scene into texture and
use it in later rendering. I have been told of the "to_texture" message of
jit.render and have checked out the example in jitter tutorial. But I
still could not figure it all out and always produce error message,
"warning: method screen_grab called on invalid object".

to_texture is currently broken, to everyones dismay. We all patiently 

await c74s fix. currently there is no way to render a whole scene to 

to_texture is currently broken, to everyones dismay. We all patiently  
await c74s fix. currently there is no way to render a whole scene to  
a texture on the GPU.

But why would the example "jit.gl.render.radialblur" still manage to use

I see.
But why would the example "jit.gl.render.radialblur" still manage to use
it ?

I am using to_texture regularly. The destination context size must 

I am using to_texture regularly.   The destination context size must  
match the texture size exactly.

can you provide an example patch? Wesley stated it wasnt working

"No there was a big discussion in november and render to texture does

not currently work at all. I agree that this (excuse my french)

Apologies for mis-info if it indeed works. id love to get this working.

can  you provide an example patch? Wesley stated it wasnt working

"No there was a big discussion in november and render to texture does
not currently work at all.  I agree that this (excuse my french)
sucks.

Yes, the radial blur example works, but I was referring to the

@capture attribute of jit.gl.render. The to_texture message isn't

very flexible and I find it very cumbersome. Personally, I like to

render to a pbuffer. Ideally we could also get textures from the

sorry for any confusion, still waiting for 1.5.3,

Yes, the radial blur example works, but I was referring to the
@capture attribute of jit.gl.render.   The to_texture message isn't
very flexible and I find it very cumbersome.  Personally, I like to
render to a pbuffer.  Ideally we could also get textures from the
depth buffer as well.

sorry for any confusion, still waiting for 1.5.3,
wes

way to make baby jesus feel like an asshole! I forgot all about that 

way to make baby jesus feel like an asshole! I forgot all about that  
patch. thanks.

by the way, what do you mean getting texture from depth buffer ?

Slab Help!!!