Start time for gravity expression

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irmel
Posts: 1
Joined: April 13th, 2005, 7:33 am

Hello everyone,

i want to use the gravity script from Dan Ebberts. It works perfect for me but i have no solution how i can integrate a start time via a time variable or a marker like: if (marker.numKeys > 0 && marker.key(1).time < time){

Here is the original script:

Code: Select all

Vy0 = 0; //initial y velocity (pixels/second)
Vx0 = 0; // initial x velocity (pixels/second)
g = 2500; // gravity (pixels/second/second)
floor = 1000;
e = .82; //elasticity
b = floor - position[1];
h = b + Vy0*Vy0/(2*g);
T = Vy0/g + Math.sqrt(2*h/g);

if (time < T){
	y = Vy0*time - g*time*time/2 + b; 
}else{
	Vy = -(Vy0 - g*T); 
	while (true){
		Vy *= e; 
		t = T; 
		T += 2*Vy/g; 
		if (time < T){ 
			t = time - t; 
			y = Vy*t - g*t*t/2; 
			break; 
		}else if (T - t < thisComp.frameDuration){ 
			y = 0; 
			break; 
		}
	}
} 
[position[0] + Vx0*time, floor - y]

Does anyone have a solution?
Many thanks for your help!

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