What software do you all use to render the 3D images?

Thanks

First of all I want to apologize because of my bad English. Thank you so much for this amazing tool, it is being very useful for me.
I have the same problem than Robert. It works but wthout texture, and I am working with the banana example and GLGravity project to be sure that I am not making mistakes, and nothing. Could you help me to solve that please? Thank you Heiko.

unfortunately, the script currently neither supports materials nor separate groups of faces. Both would be required to colorize your models. Sorry for that.

If you come up with a workaround or a patched version of the script, feel free to post it here!

I was just writing back again in regards to my last post, to give you more specifics as to what would be useful to include in the script.

The .obj file that was produced for my 3D model contains color shading information such as the one below since I did not use an actual texture:

g pSphere1
usemtl initialShadingGroup
f 1//1 2//2 12//3 11//4
f 2//5 3//6 13//7 12//8
f 3//9 4//10 14//11 13//12
f 4//13 5//14 15//15 14//16
f 5//17 6//18 16//19 15//20
……

So I was wondering if there would be any way to parse these values into the equivalent in OpenGL ES that the function glColorPointer(..) would be able to take.

Thanks,

Carlos.

I do have one question though. If an object (3D object that is) was painted with some colors instead of using textures, is there any way to obtain the color data in the obj file and then be parsed to the C style arrays like your script does it?
The color array that I am talking about would be used in the function: glColorPointer(…) of the OpenGL ES API’s.

Please let me know either by email or directly in this blog.

Thanks in advance.

great to see that someone even tries to use this for VS! Unfortunately, I cannot assist you without further information. Did you try to narrow this down already? How does a simple header file (e.g. the examples) behave? Are you able to visualize anything loaded via glVertexPointer? How do these arrays differ from those generated by obj2opengl?

Last night at about 4AM, I think I figured this ‘bug’ out. Turns out it is not a ‘bug’ at all, and has nothing to do with the obj2opengl script.

If you manipulate a mesh in Silo and try to export it as a .obj, Silo will export it as Quads, not Triangles. Before you export your model from Silo, you must select it and choose “Modify” -> “Triangulate” or [Control + Shift + T]. Once you do this, you can export your model from Silo, run obj2opengl and the iphone will render the .h properly.

Thanks to Jeff LaMarche for confirming the solution. Hope this post saves someone a couple days.

Thanks again Heiko, for such a great little script.

best wishes to all,
ty

Thanks for getting back to me. Great little utility! I am really interested in figuring this out and appreciate you taking the time to look at it. I posted both a cube and sphere here: http://gist.github.com/333101

Both models have the same visual artifact.

cube.obj: http://gist.github.com/raw/333101/b24c888179d871c4355cbd54a21ad616b4afa3d1/cube.obj

sphere.obj: http://gist.github.com/raw/333101/e2b4dc69df4f25bd0196817fc3f5d7ee5aec2b9a/sphere.obj

I have tried dozens of models, all have the same issue. For what it is worth, Blender can’t open Silo .obj files, so perhaps Silo went off standard.

Anyway, thanks again…. Wow, “Blender makes my head heart.” Apparently Blender makes me funny too.

please provide the .obj file of the most simple version with errors you are converting from (e.g. a cube). I think, the format of the .obj file is slighty different from what the script expects.

I seem to be experiencing some problems converting Silo 2 .obj files to .h files with obj2opengl. The conversion appears to work and I am able to load the .h file on an iphone using GLGravity. But the iphone only seems to render the model partially, in a triangle pattern as indicated here: http://imgur.com/fGN8f.jpg

I found another script, for blender, which enabled me to export solid models:
http://iphonedevelopment.blogspot.com/2009/07/improved-blender-export.html

But I would prefer to model in Silo. Blender makes my head heart. Any idea what’s going on here?

What is “Center” that script saying ?
Center:

I have two models and i have no success draw it correctly in space.
I’ve tried glTranslatef to “Center” and glScalef by “Scale by” before rendering – but my models located in space at the wrong coordinates.

How can I draw 2 models on their coordinates same as in 3dMax?

thanks,

Thanks for answer. Do you have a plan make script working with some textures ?

and my code to draw it:

glPushMatrix();
glBindTexture(GL_TEXTURE_2D, textures[13]);
glVertexPointer(3, GL_FLOAT, 0, cubeVerts);
glTexCoordPointer(2, GL_FLOAT, 0, cubeTexCoords);
glDrawArrays(GL_TRIANGLES, 0, cubeNumVerts);
glPopMatrix();

I have been having problems getting the UV texture coordinates to work.
Here is a screen shot of what it looks like in Maya: http://imgur.com/z2Ica.png
and what it looks like on the iPhone: http://imgur.com/A1alQ.png

Does anyone know how this could be fixed?
Thanks in advance for any help

But what if the object 2 or more textures?
thanks.

I made a small change to this so that it interleaves the vertex data in one contiguous array, according to http://developer.apple.com/iphone/library/documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/Performance/Performance.html

obj2opengl.pl:
http://docs.google.com/leaf?id=0B3MMs33O0RexZDUzZDU1ZjItMjRlZi00OGQwLThkOTktN2RkYWM4MzNiMDM3&hl=en

Example output (cube.h):
http://docs.google.com/leaf?id=0B3MMs33O0RexMGY0YTI0NjAtY2E1MC00MGYwLWIxM2EtMGRmYzExMzE0ODUz&hl=en

Example draw (note the required stride constant):

glVertexPointer(3, GL_FLOAT, cubeStride, cubeVerts);

glNormalPointer(GL_FLOAT, cubeStride, cubeNormals);

glDrawArrays(GL_TRIANGLES, 0, cubeNumVerts);

should be:
print OUTFILE “glTexCoordPointer(2, GL_FLOAT, 0, “.$object.”TexCoords);\n”
if $numTexture > 0;

It stops glTexCoordPointer appearing in comment.

Nice script though!

your are absolutely right. The normals will be transformed (even scaled) according to your matrix. If you are an iPhone developer have a look at the GLGravity example to learn about lights and OpenGL. Also, this tutorial seems to introduce lights and normals quite extensively: http://www.falloutsoftware.com/tutorials/gl/gl8.htm

I’m a complete newbie when it comes to open gl, so pardon my ignorance.

But when I create a simple object with normals, and render it all, as per your examples. If I then place a light above the object, and then rotate say a cube. It seems to me that as the cube rotates around the axis, the backside of it becomes dark when facing the light, rather then the side facing away form the light becomes dark.

Do I need to recalculate or transform the normals for the light to be correct?

I’m doing a push and pop call, then translate the cube I’m drawing. I would have thought that the face facing the light would become lighter. Isn’t that what the normals are for?

could you please provide your obj file so I can try to reproduce your error?

I wondered if you could help me. I created an object in Carrara 6 pro and exported to wavefont obj file. I ran your script and I got “Illegal division by zero at ./obj2opengl.pl line 294″ I checked this and it seemed to be related to scale, so i specified -noScale and it appeared to work. However upon further inspection the header file was in fact invalid and contained nothing like the expected format, instead just a copy of the original obj file. I’m new to all of this, so forgive my ignorance but do you have any idea what I’m doing wrong?

Thanks in advance for any help

Regards

Thanks!

-bash: ./obj2opengl.pl: Permission denied

Keep up the great work!

Ryan

Loading the corresponding image file is another story, though. If you are not familiar with OpenGL ES and texture mapping these links might be helpful:
http://iphonedevelopment.blogspot.com/2009/05/opengl-es-from-ground-up-part-6_25.html
http://web.me.com/smaurice/AppleCoder/iPhone_OpenGL/Entries/2009/4/1_OpenGL_ES_05_-_Texture_Mapping_Our_Square.html

/ the converter produces a weird bug when skipping number values and leaving only commas in the array definition when the model is not in expected format, I guess; however when I exported the same model with triangles only, it works perfectly /

however, since I am a complete noob in this field I even don’t know if something like this makes sense, but is it possible to automatically apply a corresponding texture to a model defined like this in xcode? if so – how ? – does there exist a corresponding apple tutorial/concept which can be easily adopted for this ?
thank you very much!
r.

as a starting point, use the GLGravity sample from the dev center and add the banana.h to the project. Now, replace the #import “teapot.h” in AppController.m with the banana.h and build the project. You will find to areas with errors, replace these lines with the ones given on top of the banana.h. First, replace the whole loop after “// Draw teapot” with the single glDrawArrays statement. Second, set the vertex and normal pointer as stated in the comments of banana.h. That’s it.

I am sure you will find some sample code to learn the handling of textures, too.

really amazing script. But I was trying to use to render your example in iphone simulator Xcode project. I don’t know where I failed but I didn’t see the bananas on the screen. I was trying to adjust glOrthof thinking should be big enough to see it, but doesn’t work. Could you please provide your sample Xcode project or how do you implent that?

Thanks

thank you for your comment. Your exported obj file partly contains faces with 4 vertices each. Currently, this script has these known limitations, though: “This script expects and OBJ file consisting of vertices, texture coords and normals. Each face must contain exactly 3 vertices. The texture coords are two dimonsional.”

Is it possible for you to export your model with triangles only?

I just came across this Perl script of yours (from dev forums), and it works great! I really like how you simplified things (very easy to use!) and made it cross-operational for many systems and platforms.

One gripe though: my Silo 2 exported OBJ file isn’t showing up correctly for the iPhone OS. Some faces are gone. I think it has something to do with Silo 2’s Triangulate function. Otherwise, when I deal with simpler models, it works fine.

Anyway, here’s the OBJ file:
http://www.mediafire.com/?ykzyiwd2nde

Thanks.