Re: A Z80 guy needs help!

What I wrote about rounding errors had an error itself.

> Vx = (D + delta) * sin(theta) - D * sin(theta)
> Vy = (D + delta) * cos(theta) - D * cos(theta)
>
> Again, replace D with D + delta for the next time increment.

That is wrong. It should have been:

Vx = (D + delta D) * sin (theta) - X position
Vy = (D + delta D) * cos (theta) - Y position

Replace X with X + Vx; (this is now the new X position)
Replace Y with Y + Vy; (this is now the new Y position)
Replace D with D + delta D; (this is now the new vector lenght)

"Delta D" is the distance moved along the vector in 1/1,024 sec.
"Delta D" varies with acceleration.
"theta" is the angle of the vector, and stays constant.

Mariss