Gary Lee Nelson

I have accumulated a number of 3D graphics programs to make .obj files for

jit.gl.model. Now, I would like to manipulate the data directly to warp the

shapes in real time. I am wondering if someone has created a method or tool

to translate .obj files so they can be loaded into jit.matrix. I have seen

the examples where a sphere is created directly into a matrix with plane

messages specifying each point and I love the example that creates "ghosts"

with jit.noise. I'm looking for something in between.

And a related issue in openGL...There are many examples in the openGL

manuals that could be plugged into jit.gl.sketch. However, the format of

the sketch messages is different so as not to allow simple cut and paste.

Has anyone dealt with this? Would this be a thing to do with Java?

I have accumulated a number of 3D graphics programs to make .obj files for
jit.gl.model.  Now, I would like to manipulate the data directly to warp the
shapes in real time. I am wondering if someone has created a method or tool
to translate .obj files so they can be loaded into jit.matrix.  I have seen
the examples where a sphere is created directly into a matrix with plane
messages specifying each point and I love the example that creates "ghosts"
with jit.noise.  I'm looking for something in between.

And a related issue in  openGL...There are many examples in the openGL
manuals that could be plugged into jit.gl.sketch.  However, the format of
the sketch messages is different so as not to allow simple cut and paste.
Has anyone dealt with this?  Would this be a thing to do with Java?

Cheers,
Gary Lee Nelson
TIMARA Department
Oberlin College
www.timara.oberlin.edu/GaryLeeNelson


translating-obj-files-to-jit-matrix

A) [Jit.gl.model @matrixoutput 1] -> [jit.matrix] -> [jit.gl.mesh]

Watch out for large obj files slowing down your frame rate though. Bang the

jit.gl.model once to dump it into a jit.matrix, then do transforms on that

matrix at frame rate and send to jit.gl.mesh. The output will be a Nx1

matrix; depending upon what primitive you use to render (triangles, lines,

quad strips etc etc) it might be helpful to reorganise the matrix into an

Nx3 or Nx4 shape. Start with some really simple .objs (like, cubes) to get

It's pretty hard to get transforms that make much sense visually (apart from

the obvious 'exploding triangles' and 'jittery noisy shapes' effects...) and

it's especially dependent upon the order of vertices in the .obj file.

Different packages seem to export in different ways; I've seen some with a

Oh, and quite a few .obj files don't have their normals set (they will look

weird if you have lighting enabled), so try sending a make_normals message

B) yes, or Javascript which might be simpler to write a parser in

Watch out for large obj files slowing down your frame rate though.  Bang the
jit.gl.model once to dump it into a jit.matrix, then do transforms on that
matrix at frame rate and send to jit.gl.mesh.  The output will be a Nx1
matrix; depending upon what primitive you use to render (triangles, lines,
quad strips etc etc) it might be helpful to reorganise the matrix into an
Nx3 or Nx4 shape. Start with some really simple .objs (like, cubes) to get
an idea of what is happening.

It's pretty hard to get transforms that make much sense visually (apart from
the obvious 'exploding triangles' and 'jittery noisy shapes' effects...) and
it's especially dependent upon the order of vertices in the .obj file.
Different packages seem to export in different ways; I've seen some with a
lot of zero vertices in there.

Oh, and quite a few .obj files don't have their normals set (they will look
weird if you have lighting enabled), so try sending a make_normals message
to your jit.gl.model after loading.

B) yes, or Javascript which might be simpler to write a parser in


If you create models with the same program, (Maya for instance) and 

count the number of verts and make sure they are the same, you can do 

whenever I change the xfade value, I also bang the 2 jit.gl.models, 

which then supply the morphed vertices into the 'bottom' jit.matrix. 

This way, I incur no penalty for having the xfades, the jitter matrix 

chain is inactive until I decide to morph again. the last jit.matrix 

is essentially a vertex 'buffer' that is then rendered with 

jit.gl.sketch with drawmatrix . Add a line or two to 

I just played with it live last night at an open jam, and really 

I LIVE! I LIVE! I LIVE! I LIVE! I LIVE! I LIVE! I LIVE! I LIVE! I 

You will not be saved by the Holy Ghost. You will not be saved by the 

If you create models with the same program, (Maya for instance) and  
count the number of verts and make sure they are the same, you can do  
very convincing morphs.

whenever I change the xfade value, I also bang the 2 jit.gl.models,  
which then supply the morphed vertices into the 'bottom' jit.matrix.  
This way, I incur no penalty for having the xfades, the jitter matrix  
chain is inactive until I decide to morph again. the last jit.matrix  
is essentially a vertex 'buffer' that is then rendered with  
jit.gl.sketch with drawmatrix . Add a line or two to  
make morphing smooth, and it works well.

I just played with it live last night at an open jam, and really  
enjoyed it.

I LIVE! I LIVE! I LIVE! I LIVE! I LIVE! I LIVE! I LIVE! I LIVE! I  
LIVE! I LIVE! I LIVE! I LIVE!

You will not be saved by the Holy Ghost. You will not be saved by the  
God Plutonium.

I want to work with modelmorphing but i cant get the basics to work. Probably something i'm too blind to see because i tried everything described in the forums/tutorials.

Max loads the models seperately but after an xfade i can't get the matrix to work.

I tried vade's method and the gl.sketch alternative as described in the patch below.

Please your opinion about this, I'm getting headaches!

I want to work with modelmorphing but i cant get the basics to work. Probably something i'm too blind to see because i tried everything described in the forums/tutorials.
Max loads the models seperately but after an xfade i can't get the matrix to work.
I tried vade's method and the gl.sketch alternative as described in the patch below.
Please your opinion about this, I'm getting headaches!

forgot to include the drawingmethod. i wanted to bang my head for forgetting it, but instead i'll let max bang for me

Translating .obj files to jit.matrix