Original Post
I am working on particle emitters for engine exhaust for the game I'm making, and I really need to optimize it. Right now it is taking a framerate cost of about 20fps. I would like to minimize that as much as possible. Basically, its a large number of triangular planar particles. Every update, their alpha level drops slightly (to create a fade-with-distance effect) and they move slightly backwards on the z axis. Is there a way to put particle drawing into a display list or something so that it draws faster (to the point of relatively minimal framerate cost)? I've used display lists before, but on stationary effects where nothing ever changes. here is the code to my engine-emitter subsystem: Thanks for your time, folks! [edit] I know the code there would make it very ugly. This is basically the first revision of it. I'm working on an algorithm to make the particle placement and coloring look better. [edit#2] Sorry, I just noticed I forgot the REPart definition. It has been added. [Edited by - medevilenemy on July 18, 2008 12:23:07 AM]
class REPart // Rectangular engine particle
{
public:
void InitParticle(float xmin, float xmax, float ymin, float ymax, float zc, float r, float g, float b);
void DrawParticle(void);
bool IsVisible(void);
private:
float x; // Horizontal Location
float y; // Vertical Location
float z;
float red;
float green;
float blue;
float alpha;
};
void REPart::InitParticle(float xmin, float xmax, float ymin, float ymax, float zc, float r, float g, float b)
{
float width = xmax - xmin;
width = fabs(width);
float half = (width / 2.0);
float height = ymax - ymin;
height = fabs(height);
float hhalf = (height / 2.0);
x = (((float)rand()/(float)RAND_MAX))*(xmin);
x+= (((float)rand()/(float)RAND_MAX))*(xmax);
y = (((float)rand()/(float)RAND_MAX))*(ymin);
y+= (((float)rand()/(float)RAND_MAX))*(ymax);
z = zc;
red = r;
green = g;
blue = b;
alpha = (((float)rand()/(float)RAND_MAX))*(1.0);
//alpha = 1.0-(fabs(x)/half);
//alpha -= (fabs(y)/half);
}
void REPart::DrawParticle(void)
{
float size = 0.001;
glColor4f(red, green, blue, alpha);
glBegin(GL_TRIANGLES);
glVertex3d(x, y, z);
glVertex3d(x+size, y, z);
glVertex3d(x+size, y+size, z);
glEnd();
z+=0.006;
alpha-=0.01;
}
bool REPart::IsVisible(void)
{
if(alpha > 0)
return true;
if(alpha <= 0)
return false;
return true;
}
class Engine : public Rotatable
{
public:
Engine()
{
};
~Engine()
{
};
virtual void Update()
{
}
protected:
float dx; // X location relative to parent
float dy; // Y location relative to parent
float dz; // Z location relative to parent
float pitch; // Pitch relative to parent (rotation about parent's X axis
float yaw; // Yaw relative to parent (rotation about parent's Y axis
float r;
float g;
float b;
float wid;
float len;
Rotatable *parent; // A reference to the parent ship, to facilitate easier updates.
//etc
};
class Rect_Engine : public Engine
{
public:
Rect_Engine()
{
};
Rect_Engine(Rotatable *par, float dispx, float dispy, float dispz, float length, float width, float rx, float ry, float red, float green, float blue)
{
int i;
dx = dispx;
dy = dispy;
dz = dispz;
pitch = rx;
yaw = ry;
wid = width;
len = length;
r = red;
g = green;
b = blue;
parent = par;
Position = parent->GetPos();
UpVector = parent->GetUp();
RightVector = parent->GetRight();
ViewDir = parent->GetView();
MoveForward(-dz);
StrafeRight(dx);
MoveUpward(dy);
RotateX(pitch);
RotateY(yaw);
for(i=0; i<MAX_ENGINE_PARTS; i++)
{
parts.InitParticle(dispx, width, dispy, length, dispz, red, green, blue);
}
}
void Update() // Updates position
{
int i;
Position = parent->GetPos();
UpVector = parent->GetUp();
RightVector = parent->GetRight();
ViewDir = parent->GetView();
MoveForward(-dz);
StrafeRight(dx);
MoveUpward(dy);
RotateX(pitch);
RotateY(yaw);
for(i=0; i<MAX_ENGINE_PARTS; i++)
{
if(parts.IsVisible() == false)
parts.InitParticle(dx, wid, dy, len, dz, r, g, b);
else
parts.DrawParticle();
}
// CODE FOR DRAWING THE BLOODY THING HERE
}
private:
REPart parts[MAX_ENGINE_PARTS];
};
