I am an openGL beginner. I need to build a c/c++ application which displays 3d models in augmented reality. For AR i'm using ARToolkit. In the app it must import 3d models built with modelling softwares like blender,sketchup etc.. the models might be .obj,.3ds,.collada(suggest me any others if any??).
ARToolkit mainly uses opengl to render(AFAIK), the 3d objects to camera input.
Is it possible to load 3d models/objects at runtime dynamically. what libraries are existing if any for this?
I want to have keyboard interaction with the models also where i can move specific parts of the model(eg: rrotate wheels of a car)
The models here maybe as simple as a simple house to character(man/woman).suggest me the resources i need for this and any technicalities i missed. I prefer if possible my code to work with opengl 1.4
You will need some import mechanism to import meshes in various formats into your runtime format. OpenGL (or DirectX) doesn't specify how your meshes must look on disk, and there is various stuff stored on disk that is not required for rendering. Basically, you need a way to get the vertex positions and attributes from the file, and optionally an index list (if you render using indexed triangle lists, which you probably should be doing.)
The easiest for sure is .obj, which is an ASCII format that you can easily parse and which is supported by many applications. Otherwise, look at libraries like Open Asset Import.
However, I would assume you are looking for an OpenGL based rendering system, which does the rendering for you as well as the mouse interaction. There are lot of existing engines you can use out there, for instance, Ogre3D or IrrLicht. IrrLicht is easy to use and provides support for a bunch of the formats you mentioned. It you must stick with ARToolkit for rendering, then you can probably easily convert the formats from either engine to whatever ARToolkit expects.
I'm very recomending you to try http://assimp.sourceforge.net/lib_html/
It supports a lot of open/not-very-open data formats, skelet-animation, affine transfer animation, etc.
Related
I'm having problems understanding the the usage of VS2012's 3D features in a project. I'm current building a 3D project using DirectX (Direct3D) and want display a simple 3D object (teapot) for starters. I understand the usage of the shadergraph which is of great help, but when it comes to loading an FBX model, is there an alternative to using the Autodesk FBX SDK built in or am I just stuck with it (FBXSDK)?
Generally, is there anything in VS2012 for C++ similar in nature to how XNA uses it's content pipeline to simplify loading and working with models?
You will definitely need to manage the translation from the format of your model files to the typical D3D mesh/meshpart arrangement. You can get sometimes find models in the old .x format, which corresponds to a Direct3D model. This page has some good reference for loading .x files and also links to exporters for maya and max.
OTOH If your source data is in fbx, use the fbx sdk; it's just simpler than any alternative way to get fbx data. You'll need some library for importing 3d models and although they're all limited in different ways FBX has the advantage of being supported by the widest variety of DCC apps. There are text and binary versions of the FBX format, so if you're interested in manual debugging you can use the text based version to make it easier to crosscheck your results. This sample discusses using the FBX SDK with DirectX 11 - although it is in the context of vs 2010, there may be issues moving to VS 2012.
If you go with another intermediate format you should look for one supported by the 3d tool you'll be using or the model vendor you are buying from. Collada is the most widely available interchange format, and it's based on XML so you could probably implement your own loader -- however it's also notorious for complexity and inconsistent standards so I'd avoid it unless you have a compelling reason or a big trove f Collada format files.
If your needs are very simple and don't include animation, the OBJ format is widely available and easy to implement on your own -- however it does not support animation.
is there anything in VS2012 for C++ similar in nature to how XNA uses
it's content pipeline
As far as I know, there is no such thing. You will need your own solution, as always in native C++ world =). Probably, you can make use some of the modern rendering engines: Unity, OGRE, Irrlicht, Torque, etc.
when it comes to loading an FBX model, is there an alternative to
using the Autodesk FBX SDK built in or am I just stuck with it
(FBXSDK)
As far as I know, FBX is a closed proprietary format, so you stick with FBX SDK.
Another ways (from gamedev view)
FBX format is a terribly complicated and multifunctional. Typically, you don't need FBX to draw teapot. You don't even need FBX to create a good game.
to just draw teapot you, probably, better take another simple (or not so simple) format, such as .obj, .dae or .3ds. You can load it using 3rd party library, such as assimp (which is just few lines of code) or roll out your own loader (which is not so hard either).
to draw some meaningful interactive "teapots world" you will also need to wrap them into some kind of scene: scenegraph is a common solution.
mid-size game labels typically crate their own format, converter and loader for it:
artists create models in their favorite 3D editor
then they convert it using converter: convert to custom binary .mesh format. This can be done via plugin for 3D editor or in small standalone app
in C++ app, programmers just load .mesh, deserialize to structs and classes and use it.
serious game labels develop their own content pipelines: it can include multiple custom formats (static mesh, animated mesh, etc.), loaders (to load and stream content into app), 3ds max/Maya/Blender plugins, visual scene/level editors (to make artists happy). All content is created and managed by artists, so programmers don't need any integration of content to their IDEs.
Visual studio 2012 actually has it's own model processor now.
You can add different meshes to your project(I think that it natively supports .dae, .fbx, and .obj) and it'll spit out a ".cmo" model that's simple to parse.
The directX Toolkit also has pretty good support for loading the format, so if you're already using the DXTK, then I recommend seeing if the model loader meets your requirements.
I want to create a robot and want to move it in OpenGL. I will create the model in 3DsMax.
I was wondering about importing and moving it in OpenGL.
In which format should I save my file in 3ds Max so that I can import it in OpenGL?
Should I use pivots or save each part of the robot as a seperate file?
Does OpenGL support pivots?
OpenGL has surprisingly little to do with the answer. OpenGL is only used to draw your geometry. It is not a rendering/game engine/scenegraph in itself. Therefore loading a mesh and animating it is something you should take care of, subsequently informing OpenGL what it has to draw.
You can however make your life a bit easier by looking for OpenGL based rendering/game engines/scenegraphs out there that already provide the support you desire. But you'll have to take a look at that yourself. Then export your mesh in whatever suitable format your engine supports. OpenGL itself holds no relevance to whatever file format you wish to use. If you or your engine can deal with it and get all the relevant information out of it, you can use it.
Suppose that I have a 3d model with animation in, say, Blender. I need to export this model to some file and then use it in OpenGL app, i.e. without hardcoding animations, but reading them from file. What format is the best solution?
OpenGL doesn't support any format directly, but the classic OBJ file format lines up very well with drawing with vertex arrays. Basically, OBJ lists all vertices independently of the geometry. This way, several objects can share the same points. All kinds of groupings are also possible.
Also, it is one of the earliest formats to support a wide range of spline curves & surfaces, including Bezier, B-Splines & NURBS.
A basic decription can be found here:
http://en.wikipedia.org/wiki/Wavefront_.obj_file
The complete OBJ spec can be found here:
http://www.martinreddy.net/gfx/3d/OBJ.spec
It's not as modern as WebGL, but it's simple, human readable and widely supported.
What format is the best solution?
OpenGL doesn't care about file formats. So feel free to choose whatever suits your needs best. Due to the rise of WebGL I started dumping whole Blender scenes into collections of JSON formated files.
I'm working on an Augmented Reality project that uses multiple markers to get positions for 3D models that I'm planning to overlay. (I'm doing this from scratch using OpenCV and I'm not using ARToolkit or any other off the shelf marker detection libraries).
Environment: Visual C++ 2008, Windows 7, Core2Duo 1GB ram, OpenCV 2.3
I want the 3D models to be manipulated by user so it will turn out to a sort of simulation.
For this I'm planning to use OpenGL. What are your suggestions, recommendations? Can the simulation part be done by using OpenGL itself or will i need to use something like OpenSceneGraph/ODE/Unity 3D/Ogre 3D?
This is for an academic project so better if I can produce more self-coded system rather than using off-the-shelf products.
it would seem that OpenGL is pretty enough for your needs (drawing a model with a specific colour and size).
If you're new to OpenGL, and you are not going to be using it for your future projects, it might be easier to use the old fixed-function pipeline, which already has the lighting and color system ready and doesn't require you to learn how to write shaders.
For your project, you will need a texture where you would copy the image from camera using glTexSubImage2D() which you would in turn draw to background (or you can use glDrawPixels() in case you don't require any scaling). After that, you need to have your model, complete with normals for lighting. Models can be eg. exported from Blender or 3DS Max to ascii format, which is pretty easy to parse. Then you can draw the model. Colors can be changed using glColor3f() before drawing the model (make sure you don't specify different color while drawing the model). Positioning of the models is done using matrices. The old OpenGL have some handy and easy-to-use functions for rotating and translating objects. There are also functions for scaling the objects (changing size), so that is covered pretty easy. All you need is to figure out camera position, relative to the marker (which i believe is implemented in OpenCV).
If you were to use the forward-compatible OpenGL, you would need to set up vertex buffer objects to contain model data and write vertex and fragment shaders to shade and display your model. That's kinda more work for which you get extended flexibility. But you can use shaders in the old OpenGL as well, if you decide you need them (eg. for some special effects).
Learning how to use a scenegraph or an engine (ogre) can take some time, i would not recommend it for your task.
I am trying to develop a 3D game in openGL and i need to create many 3D objects.. I am a begginner in openGL.. I have tried with many 3D softwares like Blender , MODO, Unity 3D and Cheetah.
I am easily able to create my objects with these and exporting as Wavefront .OBJ, and converting it to a header file using a perl script. This header file is added to my openGL project..
The 3D objects are seen, but its not perfect. The script i used is to convert the .OBJ to .h using TRIANGLES.. And the object is seen with triangles. Its not full.. No way when i used TRIANGLE STRIP,FAN..? Problems with the vertices..
Is the problem with my Script or is it the wrong way i have gone..?? Or is there any other best ways to directly import 3D objects to openGL..??
The below link is the best one which you can get for 3D objects to openGL.. i got the scripts from these..
http://www.heikobehrens.net/2009/08/27/obj2opengl/
please help..
You don't want to go that way. Direct drawing mode (using TRIANGLE and friends) is extremely slow in OpenGL.
Instead, you should pick a decent format and write a loader for it (or use one found on the web). Good formats would be 3ds, obj if gzipped, collada.
Here's an example tutorial on loading from Milkshape files.
Once you load your objects programatically, you can use Vertex Arrays, or even better VBO's to display them. This is waaay faster.
Google for a mesh loader for your favorite format, or write one yourself.
I have written a reader/renderer for AC3D files that works fine on the iPhone (OpenGL ES)
Feel free to have a look at it here.
There is also an obj loader by Jeff Lamarche at google code.
AC3D can reduce the triangle count pretty good and as an alternative I ported QVis to the mac. My reader/renderer also tries to build tri-strips.
About VBO's. I have not seen any gained performance when using them in the iPhone. I'm not the only one.