Structuring POD Files

PowerVR Insider
1


Hi,


I'm starting to develop applications for the iPhone and I am having some difficulty understanding how to structure my POD files that so I can use them in my application. I'm new to using 3D models in my application but I've successfully got the POD files working in my Xcode project (thanks to Oolong). What I'm trying to understand is how many different POD files I really need for my application and how I would go about structuring each POD file.


The application I am planning on building is a game that will have 10 different Levels. Each level will have 20 different models that I will need to render at different times. Each level will also have a common set of 3D objects that will be used. The application will have a single fixed camera and single set of lights.


So my question is, when I create my 3D models in 3D Max, should I export all my models into a single POD file (including a single camera and set of lights)? Looking through the training coarse examples, I noticed a camera and lighting are required in each POD file. Using this approach would mean that my POD file could contain 100 3D models.


Or, should I structure my POD file to only contain a single 3D model and exclude any camera and lights? I could then write code to read each 3D model from the POD files as it is needed. I would also have custom code in my application that would handle my camera and lights (outside any POD file).


In addition, what is the bare minimum that is needed in each POD file so that I can successfully render the 3D model with animation inside my application?


Any assistance or guidance that you could provide would be greatly appreciated.


Thanks - Jack

2

Well, it really depends what kind of code are you going to use for rendering your models and thus it  follows that you should structure your POD files the way your engine/rendering code expect them to be.


There is no  "standard" way to  render a POD based model ... just like there is no standard way to render a collada or any other 3d file.

 
3

I have to agree with warmi here. We tend to use a single POD file per demo internally, but there are some obvious drawbacks with this such as needing to load all geometry and animations into memory at once. For larger projects it may be that multiple POD files is a better way of proceeding, but I must admit that this hasn’t been extensively tested here. In your case it strikes me that having a POD per level may be desirable, possibly with a separate POD or PODs that contain models that are common between the levels.





The camera and light requrement is specific to those demos that you’ve as they wouldn’t know how to render the POD sensibly otherwise. Some work was done internally using PODs that only contained animations, for instance, certainly we have PODs that only have mesh information and no lights/cameras.





A better test of how valid a POD file is probably to open it PVRShaman, but as warmi says it’s really up to you.