Written:	Spring 2001
Last Touched:	Spring 2001

Introduction

I wrote this particle simulation as a technology demonstration for part of a larger game that never was finished, or even coordinated enough to really get started. Cleaning up some of my old DirectDraw and DirectInput code, I hacked together this neat demo in a couple hours. Five minutes of entertainment, guaranteed.

What Was Difficult?

Not much. Refactoring code was fairly fun, but I may have got a bit carried away as I tried to combine the best aspects of two of my old graphics libraries. At this point, I didn't have enough of an idea about object oriented design to come up with a cohesive DirectDraw/DirectInput wrapper, so there are plenty of naked COM calls in the code.

How nasty is COM to work with? Here's a code snippet to set the video mode.

Fvideo.c (excerpt)

bool FVideo::SetVideoMode(int iw, int ih, int ibpp, int ihz) { HRESULT ddret; DDPIXELFORMAT ddpf; // initialize directdraw if(!InitializeDDraw()) goto Failed; // attempt to set the cooperative level for fullscreen ddret = lpDD->SetCooperativeLevel(g_MainWindow, DDSCL_FULLSCREEN | DDSCL_EXCLUSIVE | DDSCL_ALLOWREBOOT); if(FAILED(ddret)) goto Failed; // attempt to set the video mode to what was specified ddret = lpDD->SetDisplayMode(iw,ih,ibpp,ihz,0); // ...

Lots of bitwise flags, lots of headache-inducing preprocessor macros that declare namespaces, lots of merely adequate online documentation.

Thankfully, I didn't have to figure out a lot of this on my own; I had both an article from Dr. Dobb's (fine) Programming Journal detailing DirectDraw work as well as a hefty tome of wisdom by famed game programmer Andre LaMothe. Even with these two references, it was still a bit of hit-and-miss with DirectDraw. After several unresponsive blank screens, I memorized the keystrokes to switch to Visual Studio, open the Debug menu and stop the program, saving me a reboot and sometimes letting me track down the exception that I had been unable to see in full-screen mode.

What you need to compile & run this

For Windows, I'd recommend Microsoft Visual C++ 6.0 or greater, since that's exactly the tool I used to develop this project. You'll also need the DirectX 7.0a or newer SDK -- thanks to COM, they're backwards compatible. This is currently available from:

http://msdn.microsoft.com/library/default.asp?url=/downloads/list/directx.asp

For Linux, you're out of luck. Unless you feel like messing with WINE, but neither I or the WINE programmers will guarantee you any degree of success. But hey -- it never hurts to try. Let me know if you manage to get it working, and I'll give you something cool for your efforts.

Controls (also listed during simulation)

Spawn Particles:	Left Mouse Button
Increase Initial X Velocity:	Right Arrow
Decrease Initial X Velocity:	Left Arrow
Increase Initial Y Velocity:	Up Arrow
Decrease Initial Y Velocity:	Down Arrow
Increase Gravity:	Page Up
Decrease Gravity:	Page Down
Increase Wind (X-axis Gravity):	Insert
Decrease Wind (X-axis Gravity):	Home
Decrease Red:	Z
Increase Red:	A
Decrease Green:	X
Increase Green:	S
Decrease Blue:	C
Increase Blue:	D
Increase Particle Time To Live:	F
Decrease Particle Time To Live:	B
Increase Number of Initial Particles:	- (Main Keyboard)
Decrease Number of Initial Particles:	= (Main Keyboard)
Quit:	Escape, Alt+F4

Executable	particle.zip (310 K)
Source	particle-src.zip (312 K)