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quickJava

OpenGL 3ds Max help.

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quickJava    122
Hi everyone, I'm opening my talk by mentioning that I'm Vietnamese so I'm sorry if my English is not good. Before answering my question, you may want to know where I am, and what I know. This might make it easy to know where to start answer to such a noob :). OK, my only major thing related to game programming was the project for my Graphics subject ( at university ) with a high mark. It was 3ds Max like. I just learned 3ds Max style and how comfortable it is to use. I didnt learned more than that since I wanted to make the program by myself, with my own imagination. just a book and no open source program was used. I created my own wireframe format, objects created with that format were filled using Phong shading and Lampard technique. Besides, I created some features such as: moving, creating object with mouse, selecting deleting, and a net-liked floor to help users have an awareness of where their objects are. These features are easy to use just by hot keys and mouse. Although I felt a little satisfy, now I know that I should use the world standards to do similar things. Before using those standards, I must learn them, of course. So now, I'm learning 3ds Max and OpenGL, and more. I need your help, about experience and knowledge. I would love small examples and hate complete sources. So here are my silly questions: - Is 3ds Max has its own standard to mark a particular data as basic object type or what? If yes, what are they? Although I know how to read the raw data, I don't know which data in the 3ds file is equivalent to a vertex on the output object that I'm seeing, for example. - I intend to create my own common graphic format to make it a standard for communication between engines and data. Is this a bad thought? Why? - What are the most common basic graphic definition used for rendering 3d object, for example, vertex, texture? __________________________________ Here's why I am asking you such silly questions. It's not important but if you want a reason, then it's here: I'm a last year IT student, and focusing on C/C++, Java technology. Besides, I love Math and Physics so I decided to create a Graphics engine for my graduate project although I have never create a part of a real game. I love Java for its elegant and erudite style. To me, JVM is a proof that Sun knew how right the standardization is long time ago, and how intelligent they are when they have successfully standardize many complex platforms just like the way we are standardizing everything now. I recently knew that Java's getting faster now. And Just-in-time programs run slower than pre-compiled programs is just a myth, not truth. With all these good news, I feel joyful continue using Java as one of my main languages. I love challenge, so I'm not worry that I'm still a game programming newbie. I have you help me :) P/S: Vietnameses are very friendly, If you had been here, you may be more than surprise. So if you feel free to be friendly as a Vietnamese, please fix my grammar or vocabulary errors. Thanks a lot.

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Lord_Evil    680
OK, I'm not sure if I fully understand what you're asking but I'll give it a try:

1)
Get the 3ds max SDK and the SDK help, there you can learn on how 3ds max organises 3d data. They use some common representations like triangles, edges etc. but they also use multiple normals per vertex which isn't the case in many engines as far as I know.

2)
Generally you should use a common file format like .3ds or .md3. There are plenty of editors that can read and write those formats out there so you could use them without having to write an exporter for each of those. Additionally the exisiting formats are proven, there exist many models stored in those formats and it should be easier to use them in your engine - either via a 3rd party library or your own importer/exporter.

I'd suggest you use the standard formats for the beginning. If you later discover that there is no format that meets your requirements you can create your own by then.

3)
Basic data for rendering an object are the vertex positions and definitions on what type of primitive is used (generally triangles) and of which vertices a primitive consists - either by position in the buffer or by index.

For lighting you need:
- normals for calculating light intensity (based on angle to light source)
- materials for defining light color and intensity (based on reflectance etc.)
- you can also use colors to define the materials instead of the material structure

For texturing you need texture coordinates and textures.

Other advanced features like animation use additional data per vertex but the above should suffice for a beginning.

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iNsAn1tY    476
Hi.

Quote:
Original post by quickJava
- Is 3ds Max has its own standard to mark a particular data as basic object type or what? If yes, what are they? Although I know how to read the raw data, I don't know which data in the 3ds file is equivalent to a vertex on the output object that I'm seeing, for example.

There's a lot of info on the 3ds file format (Google "3ds file format"). Quick link to something you might find useful: an open-source project to write a library for loading 3ds files - 3DS File Format Library

Quote:
Original post by quickJava
- I intend to create my own common graphic format to make it a standard for communication between engines and data. Is this a bad thought? Why?

Do you mean something like COLLADA?. The problem with writing a "standard" for this kind of thing is that games have vastly different needs. A first-person shooter won't need the same data as a real-time strategy game, for example. It's a good idea to create game content in your favourite tool (3ds max, Maya, XSI, blender, whatever), then write an exporter to your own file format for use in your game or engine project.

Quote:
Original post by quickJava
- What are the most common basic graphic definition used for rendering 3d object, for example, vertex, texture?

Depends on how "high-level" the data is. In the native file formats used by content creation tools (3ds max, Maya, etc.), the data isn't stored as just vertex data, material data, and so on. It's stored in a very high-level form. 3ds max, for example, stores objects in .max files by writing the original object, then all of the modifiers which are applied to it. A saved, final object doesn't actually "exist" in the file at all. When you open the file, 3ds max reads the original object, then applies all of it's attached modifiers, creating the final object you saved.

Formats like 3ds and most model formats used by games and game engines do generally store objects as collections of vertex data, material data and animation data. I guess there are special cases, such as parameterized splines (eg. Bezier, Catmull-Rom) or surfaces (eg. NURBS) which could be built by the game or engine on-the-fly, but I've never come across anything like that.

If you like maths and physics, you might like to have a look at the md5mesh and md5anim files which the Doom 3 engine uses. They're human-readable 3D model files, which demonstrate how mesh and animation data is stored and utilized by a professional 3D engine. The models are skeletally-animated using quaternions (very useful, not too difficult to learn) and general 3D vector math. There's a lot of information on the md5 formats on the net. I found this one particularly helpful: http://tfc.duke.free.fr/coding/md5-specs-en.html. It might take a while to get going, but the rewards are great (animating Doom 3 monsters and marines [grin])

[Edited by - iNsAn1tY on March 3, 2007 6:11:09 PM]

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