Thread: C tutorial Help

...I don't use the Visual C++ IDE...

It would actually be more useful if you stated which compiler you do use. And the version of directx you're programming with might be handy, too.

Originally Posted by SMurf

I'm not sure whether the same can be done with the most recent version of DX, I know the above works up to DX

Yes, it's good to go. The 'c' syntax is generally:

Code:

dx_object->lpVtbl->fn_name(params);

where params is the function parameters with an additional first parameter of dx_object.

Originally Posted by SMurf

Most C people see a COM object, scream...

There's a bunch of macros defined in d3d9.h (and possibly elsewhere) that simplify the syntax. They also have the added bonus of mapping to c or c++ syntax depending on whether __cplusplus ( or CINTERFACE ) is defined. For example:

Code:

#if !defined(__cplusplus) || defined(CINTERFACE)
  #define IDirect3D9_Release(p) (p)->lpVtbl->Release(p)
#else
  #define IDirect3D9_Release(p) (p)->Release()
#endif

You guys are all barking up the wrong tree. First of all COM can be used with either C or C++ because COM has nothing to do with either. COM is not C++ and interfaces are not C++ classes. COM is a binary standard and while it acts very much like a C++ class, it still cannot be considered a pure C++ class.

COM and COM +, ActiveX, and others are readily used in VB 6 apps and other languages as well.

DirectX can be utilized from VB code and from C/C++ code. Do not confuse COM as having anything to do with C++.

If you are serious about using DirectX or any API for that matter you will soon find out that there are thousands of functions at your disposal, yet they have not been grouped together in a nice unit. For instance to create 3D models you could use the D3DX mesh library of functions. But there are a lot of them and to just use them willy nilly inside of your init functions, etc., would be a huge mess. So you encapsulate them in a nice class that provides a nice neat interface to important mesh functions or important functions for your particular use of the mesh library. Don't derive ten thousand times and stay away from virtual functions as much as possible because they have with them an associated performance hit....that may not matter in normal C++ apps but trust me it will bring your Direct3D framerates and games to their knees in a flash.

If you only code in C you can use the DirectX API but its going to be some very messy code. The reason that Quake and all those engine are C-based and not so much C++ based is that they are, in essence, writing an API for their game engine that in turn uses the DirectX API. API programming just lends itself better towards C. But if you are creating objects and such inside of your game then you will want to encapsulate their behaviors and such in a class.

Also you must be extremely careful with how you manage resources. At first glance most people would create a class to encapsulate animation, animation frames, etc. They would store the IDirect3DTexture9 pointer inside of the animation class, etc, etc. Big problem here already. This works fine for say a couple of instances of the class. But remember that each object of that type will have a texture pointer in it. Let's say we have 100 explosions happening but they all use the same animation sequence. Are you going to store 10 frames of the same animation in 100 separate sequences when they all use the same images, just at different times? Absolutely not. So what you need to develop are resource manager classes that manage all the resources for the engine. Ideally in the explosion example you would want an animation sequence manager class. In this way you could create several animation sequences during the load time and then just 'link' your objects to the desired sequence. The animation sequence would keep a list or a vector of the current frame number for each class and then return the appropriate texture to be rendered. In this way and in our example you would have 10 frames of animation and any number of objects could use or 'link' to this animation. Storing 10 frames is a lot better than storing 10*100. You will run into this a lot in game programming. Proper resource management is one of the major keys to framerates, and framerates are vital to interactive programming.