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
design my really simple patches.
Any pointer is welcome.
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…
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 ?
But why would the example "jit.gl.render.radialblur" still manage to use
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)
patiently awaiting 1.5.3
Apologies for mis-info if it indeed works. id love to get this working.
v a d e //
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,
Thx. I’ll try it out.
by the way, what do you mean getting texture from depth buffer ?