Projectile Motion: Finding Angle and Displacement in x Seconds

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Seppy
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I need to find the angle of a projectile after traveling x seconds of flight.
I know the position of the projectile, the x seconds and the velocity.

or

I need to find the displacement of a projectile after a set increment time rather than the standard, total time used in the

y=ut+1/2gt^2

This is for a physics engine, instead of keeping a constant clock of projectiles i need to update the projectiles position every x seconds. This is because for longterm flight projectiles the clock would exceed memory allocation.

What I've tryed to do is use

theta = atan(u + at)

But it gets weird results.
 
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You might find it easier to just keep track of position and velocity separately, then, as most engines do. Simply update the y-velocity by a*time_increment, and then update y and x by corresponding velocity * time_increment. If your time increments are small enough, result should be the same.

Or are you restricted to large time increments for some reason?
 
I have no idea why computing y = ut + 1/2gt^2 for a lot of succesive values of t would exceed memory allocation.

theta = atan(u + at) would give the angle of the velocity of the projectile with the x axis, IF the x component of the velocity was equal to 1. I don't really see what good this angle would do to find a new x and y, if you already know v_x and v_y.