I'm having a small problem with exporting mtl files in 3ds max. I would like to use an obj + its material library in an opengl program. The model gets exported just fine, but I loose all the reflective/refractive parameters of my materials when I export them (colors and such seem to be fine so it finds them just not completely but all materials get changed to standard). I tried exporting materials from the scene and from the mat. library aswell with the same results. Could anyone help me how to keep the reflective parameters of materials after exporting?
As you stated in the email you use Glut as API. there are several tutorials for this,
I initially thought you used a engine, and just needed some values.
But you needed more then this.
To use reflection \ environment mapping in opengl you need a shader that supports this.
So what you need to do is to implement a reflection shader, and pass the bitmap into your shader.
In the sample file it worked fine for rendered image (because 3dsmax supports it's own raytrace materials), but this does not get exported in any way.
Related
I am writing a program that will output 3D model files based on simple geometric shapes (e. g. rectangular prisms & cylinders) with known coordinates in 3-dimensional space. As an example, imagine creating a 3D model of stonehenge. this question suggests that OBJ files are the easiest to generate, but I'm struggling to find a good tutorial or easy-to-use library for doing so.
Can anyone either
(1) describe step-by-step how to create a simple file OR
(2) point me to a tutorial that describes how to do so
Notes:
* Using a GUI-based program to draw such files is not an option for me
* I have no prior experience with 3D modeling
* Other formats such as WRL or DAE would work for me as well
EDIT:
I do not need to use textures, just combinations of simple geometric shapes positioned in 3D space.
I strongly recommend to use some ASCII exchange format there are many out there I usually use these:
*.x DirectX object (it is a C++ source code)
this one is easiest to implement !!! But there are not many tools that can handle them. If you do not want to spend too much time coding then this is the right choice. Just copy the templates (at the start) from any *.x file to get started.
here some specs
*.iges common and importable on most CAD/CAM platform (Catia included)
this one is a bit complicated but for export purposes it is not that bad. It supports Volume operation like +,-,&,^ which are VERY HARD to implement properly but you do not have to use them :)
*.dxf AutoCAD exchange format
this one is even more complicated then IGES. I do not recommend to use it
*.ac AC3D
I first saw this one in flight gear.
here some specs
at first look it is quite easy but the sub-object implementation is really tricky. Unless you use it you should be fine.
This approach is easily verifiable in note pad or by loading to some 3D model viewer. Chose one that is most suitable for your needs and code save/load function to your Apps internal model class/struct. This way you will be compatible with other software and eliminate incompatibility problems which are native to creating 'almost known' binary formats like 3ds,...
In your case I would use IGES (Initial Graphics Exchange Specification)
For export you do not need to implement all just few basic shapes so it would not be too difficult. I code importers which are much much more complicated. Mine IGES loader class is about 30KB of C++ source code look here for more info
You did not provide any info about your 3D mesh model structure and capabilities
like what primitives you use, are your object simple or in skeleton hierarchy, are you using textures, and more ... so it is impossible to answer
Anyway export often looks like this:
create header and structure of target file format
if the format has any directory structure fill it and write it (IGES)
for sub-objects do not forget to add transformation matrices ...
write the chunks you need (points list, faces list, normals, ...)
With ASCII formats you can do this inside String variable so you can easily insert into or modify. Do all thing in memory and write the whole thing to file at the end which is fast and also add capability to work with memory instead of files. This is handy if you want to pack many files to single package file like *.pak or send/receive files through IPC or LAN ...
[Edit1] more about IGES
fileformat specs
I learned IGES from this pdf ... Have no clue where from I got it but this was first valid link I found in google today. I am sure there is some non registration link out there too. It is about 13.7 MB and original name IGES5-3_forDownload.pdf.
win32 viewer
this is free IGES viewer. I do not like the interface and handling but it works. It is necessary to have functional viewer for testing yours ...
examples
here are many tutorial files for many entities there are 3 sub-links (igs,peek,gif) where you can see example file in more ways for better understanding.
exporting to IGES
you did not provide any info about your 3D mesh internal structure so I can not help with export. There are many ways to export the same way so pick one that is closest to your App 3D mesh representation. For example you can use:
point cloud
rotation surfaces
rectangle (QUAD) surfaces
border lines representation (non solid)
trim surface and many more ...
Im learning openGL, basically ive created an object in Maya, im wondering how i go about exporting it, and loading it into my application ive created (it is simply a plain square room with different coloured walls at the moment.
OpenGL doesn't have the concept of models. You'll have to write your own model loader, or use one that's already out there. If you opt for writing your own, you should probably export as .obj, that's a fairly simple text based format.
I need to work with the 3d model of some places. Google Earth has the 3d building layer with "Gray Buildings" in it. This would be exactly what I would require. Is there any way to get the 3d models that are used? Is there a Google Earth API (other than the Javascript stuff)? (I'm working in .net) that would help?
Or is there at least a manual solution how I can get these models, say, into Sketchup?
Thanks a lot!
While there still isn't support for getting building geometry from Google's APIs, OpenStreetMaps does expose some data you can use. Check out this guide here:
http://wiki.flightgear.org/OpenStreetMap_buildings
Making a request like
http://overpass-api.de/api/xapi?way[bbox=-74.02037,40.69704,-73.96922,40.73971][building=*][#meta]
Will return an XML with building's base outlines and (in some cases) heights. You can use this info to extrude some very simple buildings: http://i.imgur.com/ayNPB.png
To fill in the missing height values (and they're missing on most buildings), I try to use the area of the building's footprint to determine how tall it might be compared to nearby buildings. Unfortunately, until Google is able to make their models public, this will have to do.
There is currently no way to download models from within Google Earth. Also, even is there was - extracting data is against the TOS. Many of the models come from government or private sources so there are issues with licencing the data as a whole. It is worth noting however that a lot of the models in Google Earth are located on the Sketch up 3dwarehouse so maybe you could get that data you want from there?
Also, to work with the javascript api from managed code you might want to check this control library I have put together. Whilst the controls themselves may not be applicable, the ideas behind them should get you under way. http://code.google.com/p/winforms-geplugin-control-library/ essentially there are a series of wrappers and helpers that let you seamlessly integrate the plugin into a winforms application.
You can also read more about Cities in 3d (the name of the project that developed the low-res building layer) here: http://sketchup.google.com/3dwh/citiesin3d/
I'm trying to find some free XNA friendly FBX Models to use in my test application. I found some 3DS models and converted them to FBX and tried using them, but I just see some 'lines' on the screen .. I know I may have to scale/translate them, but I tried doing this and nothing worked ... Some models won't show anything at all, not even the line artifacts ..
Any ideas where I can get fairly simply FBX models from which can be used in XNA 3.1 ?
Also, there are some models I saw which contain mutiple FBX files .. I dont want these as they require more complexity .. Right now I'm just looking for models contained within one FBX file ..
http://turbosquid.com is a great place to get some free models, but the paid ones are always better.
http://www.mixamo.com/ also has some free character models. No animations though, unless you pay. However, if you're looking for animations, Carnegie mellon university has a whole slew of motion-capture files for free. You'd have to re-rig the character yourself using 3ds max or whatever 3D program you like to use, so that they use "biped" instead of bones, that's the only way to use BVH.
Motion capture BVH files can be found here: https://sites.google.com/a/cgspeed.com/cgspeed/motion-capture/cmu-bvh-conversion
Im writing a game engine and I'm wondering what 3D model format should I use/load/export? Obj seems universal and easy but it also appears to be unreliable in that most models out there contain errors and it doesn't store anywhere near as much as other formats.
There appear to be formats specifically for games such as MD2/3/5 but Im not sure, I use wings3d if I model, and I don't know what other details beyond purely loading what I need and support from the format Id have to implement, such as would I need to implement IK? and can I use scripted per piece animation rather than Inverse kinematics and bone rigging?
Collada is an open XML based format for 3d models owned by the Khronos group(OpenGL standards body)
From the Collada.org FAQ:
The COLLADA 1.4.x feature set includes:
Mesh geometry
Transform hierarchy (rotation, translation, shear, scale, matrix)
Effects
Shaders (Cg, GLSL, GLES)
Materials
Textures
Lights
Cameras
Skinning
Animation
Physics (rigid bodies, constraints, rag dolls, collision, volumes)
Instantiation
Techniques
Multirepresentations
Assets
User data
Before worrying about what 3D formats you want to support, I think you should really focus on what features you are planning to implement in your engine. Write those down as requirements, and pick the format that supports the most features from the list... as you'll want to showcase your engine (I am assuming you are planning for your engine to be publicly available). You might even want to roll your own format, if your engine has specific features (which is always a good thing to have for a game engine).
After that, support as many of the popular formats as you can (.X, .3DS, .OBJ, .B3D)... the more accessible your engine is, the more people will want to work with it!
Collada is a nice and generic format, but like Nils mentions, it is not an ideal format for final deployment.
I use my own binary format. I've tried to use existing formats but always run into limitations. Some could be worked around, others where showstoppers.
Collada may be worth a look. I don't think that it's that good as a format to be read by a 3D engine. It's fine as a general data-exchange format though.
http://www.collada.org/mediawiki/index.php/Main_Page
+1 for Collada. You may also want a custom native binary format for really fast loading (usually just a binary dump of vertex/index buffer data, plus material and skeleton data, and collision data if appropriate).
One trend in the games industry is to support loading a format like collada in the developer build of the engine, but also have a toolchain that exports an optimized version for release. The developer version can update the mesh dynamically, so as artists save changes, the file is automatically reloaded allowing them an (almost) instant WYSIWYG view of their model, but still providing a fully optimised release format.
support Collada well, and then supply good converters to/from the other formats (this might be the hard part). This will give you maximum flexibility. Take a look at C4 engine
Collada is great, but it lives more on the 3D app side of things. ie it's best used for transferring 3D data between applications, not loading 3D data from within a games engine. Have you looked into Lua? It's widely used in games because its a scripting language that's both ridiculously quick (perfect for games) and very flexible (can be used to represent whatever data you need for your engine).