How To Compute Y Velocity For A Projectile - Emulating an online Disney game

[SunShadow]

Homework Statement

I am trying to emulate the physics in an online Disney game.

Kid vs Kat Katapult Katastrophe

It helps to describe it graphically, so if you wish to take a look, play as Kat (the right option) at the following link:

bit.ly/doqEkp

IMPORTANT: Play as KAT (not Coop) the selection on the right.

So when shot, the ball always takes the same amount of time (about four seconds) to travel either near or far.

Homework Equations

- NONE -

The Attempt at a Solution

So what I have is an initial X/Y/Z position (say 0,0,0) and destination position Xd/0/Zd (Y will be zero for start and end positions, as Y is the ground.)

If you see how the ball travels, I know I can compute the X and Z velocities by dividing distance (the difference between start and end positions) by time, but I am stumped when it comes to working out the launch Y velocity.

All I do know is that I am subtracting a gravity constant from my Y velocity every update loop of the game.

I want to shoot out the ball, so that it lands at the destination point (which I know.)

What I don't know is the Y velocity to launch the ball with.

Does anybody have any advice?

 

[anathema]

Hi there,

It seems like you are trying to simulate projectile motion in your game. In order to determine the initial velocity in the Y direction, you can use the equation of motion:

Yf = Yi + Viy*t + 0.5*g*t^2

Where Yf is the final vertical position, Yi is the initial vertical position, Viy is the initial vertical velocity, t is the time, and g is the acceleration due to gravity (which you mentioned you are subtracting from the Y velocity every update loop).

Since you know the final vertical position (Yd), the initial vertical position (0), and the time (4 seconds), you can solve for Viy. This will give you the initial Y velocity that you need to launch the ball with in order to hit the destination point.

I hope this helps! Let me know if you have any further questions. Best of luck with your game!