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Particle
Engine
Particle engines are used a lot in 3D applications.
Basically they can be defined by a large array of certain variables. X, Y,
and Z coordinates are required. Increment variables for the X, Y, Z
variables are also required.
Here's a simple example of the
particle engine array:
| #define MAX_PARTICLES
100 // Number of particles
typedef struct // Create A Structure For Particle
{
float life; // Particle Life
float fade; // Fade Speed
float x; // X Position
float y; // Y Position
float z; // Z Position
float xi; // X Direction
float yi; // Y Direction
float zi; // Z Direction
}
particles; // Particles Structure
particles particle[MAX_PARTICLES];
// Particle Array |
Other
variables could be put into the array easily, such as Red, Green, and Blue
variables.
To initialize the particles,
use this code:
int loop;
float V,Angle;
for (loop=0; loop<MAX_PARTICLES;
loop++) // Initializes All The Textures
{
particle[loop].life=1.0f; // Give All The Particles Full Life
particle[loop].fade=float(rand()%100)/1000.0f+0.05f; // Random Fade Speed
V = float(rand()%25); // Speed of the particle
Angle = float(rand()%360); // Angle of the particle
particle[loop].x = 0; // Set X position
particle[loop].y = 0; // Set Y position
particle[loop].z = 0; // Set Z position
particle[loop].xi = sin(Angle) * V; // Set X velocity
particle[loop].yi = cos(Angle) * V; // Set Y velocity
particle[loop].zi = float(((rand()%10)-5)/10) * V;
// Set Z velocity
} |
Finally, to draw the particles and animate them you will probably want to find a
texture to use. I like to use a blurry texture that blends well. Use
this code:
for (loop=0; loop<MAX_PARTICLES;
loop++) // Loop Through All The Particles
{
float x=particle[loop].x; // Grab Our Particle X Position
float y=particle[loop].y; // Grab Our Particle Y Position
float z=particle[loop].z; // Grab Our Particle
Z Position
// Draw The Particle Using Our RGB Values, Fade The Particle Based On It's Life
glColor4f(.5f,.5f,1.f,particle[loop].life);
glBegin(GL_TRIANGLE_STRIP); // Build Quad From A Triangle Strip
glTexCoord2f(1,1); glVertex3f(x+0.2f,y+0.2f,z); // Top Right
glTexCoord2f(0,1); glVertex3f(x-0.2f,y+0.2f,z); // Bottom Right
glTexCoord2f(1,0); glVertex3f(x+0.2f,y-0.2f,z); // Top Left
glTexCoord2f(0,0); glVertex3f(x-0.2f,y-0.2f,z); // Bottom Left
glEnd(); // Done Building Triangle Strip
particle[loop].x+=particle[loop].xi/250; // Move On The X Axis By X Speed
particle[loop].y+=particle[loop].yi/250; // Move On The Y Axis By Y Speed
particle[loop].z+=particle[loop].zi/250; // Move On The Z Axis By Z Speed
// Slow down the particles
particle[loop].xi*=.975;
particle[loop].yi*=.975;
particle[loop].zi*=.975;
particle[loop].life-=particle[loop].fade; // Reduce Particles Life By 'Fade'
if (particle[loop].life<0.05f) // If Particle Is Burned Out
{
particle[loop].life=1.0f; // Give It New Life
particle[loop].fade=float(rand()%100)/7500 + 0.0075f; // Random Fade Value
particle[loop].x= 0; // Center On X Axis
particle[loop].y= 0; // Center On Y Axis
particle[loop].z= 0; // Center On Z Axis
V = (float((rand()%9))+1);
Angle = float(rand()%360);
particle[loop].xi = sin(Angle) * V;
particle[loop].yi = cos(Angle) * V;
particle[loop].zi = ((rand()%10)-5)/5;
}
} |
That's pretty
much it. I know that you'll probably have questions even after looking at
this. So I'm giving you a little example program so you can experiment
with the engine. Download it here.
I hope this helps you out. =)
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This page was last updated
04/19/07
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