hi greenbug,

Glad you got it sorted.  Now just add the sound of bullets whizzing thru the air ...... 

Bob

Basically I need to plot out a rise over run to meet an angle.. The intersecting point on the line from origin to destination would be the product of the sum of the rise pluss the run which would be an distance equivalent to the speed.

   |
   |             D(x,y)
   |           /
   |         /
   2 ..... X  speed(ax,ay)
   |     /  :
   |   /    :
O(x,y)  2___________________________   

(the doted lines can't be straight they are a circle)

(ax+ay) = 4   (total speed)

But ax and ay will change based on the quadrant  the destination is in and its angle from the origin.

I cant make a circle but line(OD) will always intersect the circle around the origin based on the speed, which would be the circles radius, and follow the line no matter what angle..

This should be an easy equation and I'm sure its right in front of my face but I can't think of it.. Not enough math practice.

| D1       
|           D2        D3
|> ...........X
|      >       .            D4
|          >   .     
|             >.         
_________>_____________

'X' would be where 4 would land, which would be wrong.. the '>' would be where ax,ay  would need to land in order for the speed to remain the same regardless the Destination 'D'
I cant draw the lines but imagine them from the Origin passing threw a '>' (on the circle radius of speed) to reach a 'D' destination point..

hi greenbug

I've checked the calcs and my figures are the same for the first two data sets.

ax and ay should always give 4 so the rest are not right.  ???

My plan was to split the distance to be covered into n steps. With distance = 400 and s = 40, that would be make t = 10 and n = 100 steps.

So if x1 = 650 and x2 = 250, the distance to be covered is -400, so each step would be an increment of -4

With x1 = 1050 and x2 = 250 D = -800, s=40, t = 20, so n = 200.  Each step = -4

What happens if you ignore all the sums and just step -4 each time?

Bob

Another example of the second equation... ax = (x2-x1)/40;  a bullet near and far...

x1 = 297.25      y1 = 231.75      x2 = 250      y2 = 200      ax = -1.18125                         ay = -0.79375
x1 = 388.85      y1 = 313.65      x2 = 250      y2 = 200      ax = -3.4712500000000004      ay = -2.8412499999999996

because the distance is changing

t is computed from the distance and fixed speed so when the distance is small the travel time should be small.

When the target is near are the bullets going faster or slower?

Can you 'dump' your variables for say two bullets only, so you can check the calculations.  Get a print out of all the x positions, the value of t, the value of s.  Then it may be obvious what is going wrong.

Bob

You would think so but its not happening.. and I'm not sure why.. like I said the only thing I can think of is because the distance is changing..

as in.. bullet one is shot when x1 is relatively close to x2, the speed of the bullet is slow.... but bullet 2 is shot when x1 is far from x2 and the speed is fast..  I want both bullets to be traveling at the same speed, regardless of the distance.
p.s.  and still be on target..

I'll have to introduce my own letters.

Let (x1,y1) be the coordinates of the gun.

And (x2,y2) the coordinates for the target.

Say you want to hit the target in t seconds, advancing the action in 0.1sec jumps.

Then the number of jumps is t / 0.1

The x distance to be covered is x2 - x1, so each jump must be (x2 - x1) / ( t /0.1) in length.

So position one is x1

Position 2 is x1 + (x2-x1) / (t / 0.1)

Position 3 is x1 + 2 times (x2-x1) / (t /0.1)

.............................

Last position is x1 + (t/0.1) times (x2-x1) /(t/0.1) = x1 + (x2-x1) = x2 as required.

The ys can be worked out similarly.

Bob