Particle engines

OpenGL OpenGL: Advanced Coding
1

Hi,
I want to be able to draw some faces at paticular x,y,z coodinates and yet have them always face the camera for a particle engine. At the moment I’m using gluLookAt to position the camera but I don’t mind changing to simple tranlsations or rotations if thats the only way to do it. Thanks

2

Do you mean that the camera can move and you want the faces to rotate so that they will always face the camera?

3

Hi,

I work on a particle engine and I draw particle in 2D … project the center of the particle then I determine each 2d-vertex easily (as a particle is a quad). So I never had to rotate particle in front of the camera, that is a matrix multiplication by particle !! You can increase your framerate with this method, and u only have to project a point …

4

The techniques you described is referred to as a “Sprite”. I do not have any example code handy but an internet search should turn up a lot of helpful stuff. Good luck.

5

I personally use this two routines at the begin of the particle space drawing and at the end… hope someone find 'em usefull…

void camera::viewortho( void )
{
glDisable(GL_DEPTH_TEST);
glDisable(GL_LIGHTING);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrtho( 0, this->windowwidth, this->windowheight, 0, -1, 1 );
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
}

void camera: erspective( void )
{
glMatrixMode( GL_PROJECTION );
glPopMatrix();
glMatrixMode( GL_MODELVIEW );
glPopMatrix();
glEnable( GL_DEPTH_TEST );
glEnable(GL_LIGHTING);
}

bye

rIO.sK

6

Thanks I’ll have to try that.