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).
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 ...
I am developing an online assessment package for elementary grade math (K-6) Many questions will need to contain graphics such as shown on this image:
https://www.dropbox.com/s/xwsi91l3bp9t3de/samplegraphics.PNG
All graphics needs to be generated on-the-fly (apart from photos of real objects that are stored in a database) - so that unlimited number of problems can be created). Another requirement is that this works well on both desktop and mobile devices.
I am looking for an advice as to what language / graphics package would be best suited for this purpose. I would rather do everything in one environment. If some of the above can not be generated on the fly, I would consider (but not prefer) off-line generation of many examples that are then stored in a database.
I have considered the following
php+gd -- seems nice for manipulating images; however 3D not readily available.
jpgraph.net/features/gallery.php seems like a nice addition for spiffy graphs
There also seems to be a 3D rendered for php phpclasses.org/package/3364-PHP-Compose-and-render-3D-object-models.html -- my 3D requirements are modest (basic shapes, no animation)
JS with different plugins i.e. threejs.org/ for 3D - but this seems like an overkill for my needs
there is also js interface to html 5 canvas : calebevans.me/projects/jcanvas/
and this: keith-wood.name/svgRef.html
Google charts also seems very simple to use, but it doesn't provide everything I need
CSS3 - seems like it can do everything (??)
gnuplot (??) - not on-the-fly
Basically, I am looking for the easiest way to accomplish this, without reinventing the wheel - I am just not quite sure what the trade-offs of different approaches are.
Is it possible rip game resources from a .smc file? Specifically art, music, sprites, etc. How does an emulator copy the system it emulates?
It's possible, in the sense that the information is all there in some manner. But an smc file is basically a compiled program with embedded resources, and there isn't even a standard compiler or standard format for storing the resources that you can start from.
And as far as image data goes, there is a good chance it will be in the palettized and tiled format used by the PPU, although it's also not unlikely that it will be compressed in some manner or another. But the palette will probably be almost impossible to find by static analysis, and the tile maps are probably generated from the level data rather than being explicitly stored anywhere. You may have better luck running it in an emulator and extracting the data from VRAM.
For music, the situation is even more discouraging. SNES audio is most akin to a MOD file: instruments are sampled, and then the individual samples are pitch-adjusted and mixed to generate the output sound. The SNES provides hardware to decode the instrument samples, manipulate the pitch, and mix them together, but no high-level program (i.e. no equivalent of a mod file "tracker") to play back actual songs. So you may be able to find the BRR-encoded instrument samples in the same manner you may be able to find the image tile data, but the song data can and will be formatted completely differently in different games. Again, your best luck may come from extracting the state of the APU as an SPC file and working with that.
As for your other question, see How do emulators work and how are they written? for a previous answer on that very topic.
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/
My custom homebrew photography processing software, running on 64 bit Linux/GNU, writes out PNG and TIFF files. These are to be sent to a quality printing shop to be made into fine art. Working with interior designers - it's important to get the colors just right!
The print shops usually have no trouble with TIFF and PNGs made from commercial software such as Photoshop. Even though i have the TIFF 6.0 specs, PNG specs, and other info in hand, it is not clear how to include color calibration data or implement color management system on linux. My files are often rejected as faulty, without sufficient error reports to make fixes.
This has been a nasty problem for a while for many. Even my contacts at the Hollywood postproduction studios are struggling with this issue. One studio even wanted to hire me to take care of their color calibration, thinking i was the expert - but no, i am just as blind and lost as everyone!
Does anyone know of good code examples, detailed technical information, or have any other enlightenment? Or time to switch to pure Apple?
Take a look at LittleCMS
http://www.littlecms.com/
This page has the code for applying it to TIFF
http://www.littlecms.com/newutils.htm
The basic thing you need to know is that Color profile data is something you need to store in the meta-data of the file itself.
There is a consultant called Charles Poynton who specialises in this area. I work for one of the post production studios you mention (albeit in london not hollywood), and have seen him speak on the subject a couple of times. His website contains a lot of the material he presents and you might find something of use there. He also has a book called Digital Video and HDTV Algorithms and Interfaces which is not as heavy as the title might suggest! While these resources might not answer your question directly, it might provide a spring board to other solutions.
More specifically, which libraries are you using to write the png and tif files - you mention they are homebrew, but how custom are they exactly? Postprocessing the images in an image manipulation program (such as ImageMagick or dcraw) might allow you to inject this information into the header more successfully.
Sorry, I don't have any specific answers, but maybe something that will point you a bit further in the right direction...
As a GNU/Linux user, you’ll want to consider DispcalGUI – http://dispcalgui.hoech.net/ – a GNOME-based GUI that centralizes color management, ICC profile management, and (crucially for your case) device calibration. It can talk to well-known pro- and mid-level hardware, e.g, i1, X-Rite, Spyder, etc.
But before you get into that – you say you are generating your files to spec; are you validating your output using a test suite specific to the format in question? If not, here are three to get you started:
imagetestsuite supports the well-known formats: https://code.google.com/p/imagetestsuite/w/list?can=1&q=
The Luminous* test suite is a JIRA plugin, if that’s your thing: https://marketplace.atlassian.com/plugins/com.luminouslead.plugin.jira.testsuite.LuminousTestSuite
FLOSS Decoder implementations often have one you can use, i.e. OpenJPEG – https://code.google.com/p/openjpeg/wiki/TestSuiteDocumentation
But even barring all of those, it seems like your problem is with embedded ICC data – which is two specs in one. First, there’s the host image-file format, and they all handle embedding differently (meaning the ICC data will likely look totally different when embedded in a TIFF than, say, a JPEG or WebP file). Second, there is the ICC spec itself. It is documented here: http://color.org/v4spec.xalter – and you may also want to look at the source for the aforementioned dispcalGUI, which includes a very legible and hackable ICC profile class in Python: http://sourceforge.net/p/dispcalgui/code/HEAD/tree/trunk/dispcalGUI/ICCProfile.py
Full disclosure: I have contributed to that very ICC profile class, to which I just linked in that last ¶
That’s the basics (many of which you have no doubt covered)... beyond that, if you post more information about what exactly is going wrong, I’d be interested to look it over. Good luck with it either way.
* NB. This project is unrelated to the long-standing photography website, “the Luminous Landscape”