Forums > Jitter

jit.gl.mesh help/problem rendering

October 18, 2006 | 11:51 pm

Hi Randy, (and others)

I did some tests, and was not able to get any 3D software to export
any color data to an OBJ without using a material file.I did a quick
check, and it seems the file format only uses colors/materials
through the MTL file format. ( http://www.fileformat.info/format/
wavefrontobj/ and http://www.csit.fsu.edu/~burkardt/txt/obj_format.txt )

From my understanding of your description Randy (and the patch), I
cant use the MTL information to jit.gl.mesh?

Apologies if im being dense. Long day staring at this.

PS, here is a simple model from Wings 3D where I used vertex colors
within the app rather than ‘materials’, and a screenshot of how it
should look:

and from Jitter, even with straight jit.gl.model helpfile its grey.

v a d e //

http://www.vade.info
abstrakt.vade.info


October 19, 2006 | 1:01 am

Hi Vade,

If you look at your .obj and .mtl files you will see that though your
modeler stores vertex colors internally, these are not exported in
the .obj. Sorry, I had thought that .objs had color per vertex info
but I remembered wrong.

If you look at the matrix coming out of your jit.gl.model object, you
will see that it has 8 planes (no color info.) I would have expected
the color data for the current material’s diffuse color, at least to
be sent out per vertex, but such is not the case. So there’s really
no way to do what you are trying in this patch.

If you want to deform your models procedurally, I might suggest a
vertex shader. If you really need to use jit.gl.mesh in this way,
you might want to make a feature request to c74.

best,
Randy

On Oct 18, 2006, at 4:51 PM, vade wrote:

> Hi Randy, (and others)
>
> I did some tests, and was not able to get any 3D software to export
> any color data to an OBJ without using a material file.I did a
> quick check, and it seems the file format only uses colors/
> materials through the MTL file format. ( http://www.fileformat.info/
> format/wavefrontobj/ and http://www.csit.fsu.edu/~burkardt/txt/
> obj_format.txt )
>
> From my understanding of your description Randy (and the patch), I
> cant use the MTL information to jit.gl.mesh?
>
> Apologies if im being dense. Long day staring at this.
>
> PS, here is a simple model from Wings 3D where I used vertex colors
> within the app rather than ‘materials’, and a screenshot of how it
> should look:
>
> >

>
> and from Jitter, even with straight jit.gl.model helpfile its grey.
>
>
>
> v a d e //
>
> http://www.vade.info
> abstrakt.vade.info
>
>
>
>


October 19, 2006 | 1:16 am

Hi Randy, thanks for looking at this.

Ive tried the vertex shaders (twirl, noise, etc) that ship with
Jitter 1.6.2, and have little luck getting them to do anything
useful. Infact, before 1.6.2, twirl would consistently crash my system.

Do you have an example of a shader that deforms the vertices, but
still respects options such as color/alpha, blend mode, etc?

Thanks again. Ill def. be making that feature request to Cycling
about jit.gl.model.

v a d e //

http://www.vade.info
abstrakt.vade.info

On Oct 18, 2006, at 9:01 PM, Randy Jones wrote:

>
>
> Hi Vade,
>
> If you look at your .obj and .mtl files you will see that though
> your modeler stores vertex colors internally, these are not
> exported in the .obj. Sorry, I had thought that .objs had color
> per vertex info but I remembered wrong.
>
> If you look at the matrix coming out of your jit.gl.model object,
> you will see that it has 8 planes (no color info.) I would have
> expected the color data for the current material’s diffuse color,
> at least to be sent out per vertex, but such is not the case. So
> there’s really no way to do what you are trying in this patch.
>
> If you want to deform your models procedurally, I might suggest a
> vertex shader. If you really need to use jit.gl.mesh in this way,
> you might want to make a feature request to c74.
>
> best,
> Randy
>
>
> On Oct 18, 2006, at 4:51 PM, vade wrote:
>
>> Hi Randy, (and others)
>>
>> I did some tests, and was not able to get any 3D software to
>> export any color data to an OBJ without using a material file.I
>> did a quick check, and it seems the file format only uses colors/
>> materials through the MTL file format. ( http://
>> http://www.fileformat.info/format/wavefrontobj/ and http://
>> http://www.csit.fsu.edu/~burkardt/txt/obj_format.txt )
>>
>> From my understanding of your description Randy (and the patch), I
>> cant use the MTL information to jit.gl.mesh?
>>
>> Apologies if im being dense. Long day staring at this.
>>
>> PS, here is a simple model from Wings 3D where I used vertex
>> colors within the app rather than ‘materials’, and a screenshot of
>> how it should look:
>>
>> >>

>>
>> and from Jitter, even with straight jit.gl.model helpfile its grey.
>>
>>
>>
>> v a d e //
>>
>> http://www.vade.info
>> abstrakt.vade.info
>>
>>
>>
>>
>


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