Cannon AI, calculating angle.

OkyshoOkysho Member Posts: 158
edited December 2011 in Working with GS (Mac)
Ok, well I can't get my second player OR my CPU player to work now. I decided to give the CPU a try since I ran into trouble doing player 2.

The problem here is, I can't get the CPU to calculate the angle of trajectory to fire at the player. I'm using the standard formula:
(1/2)*asin(9.81* self.Distance from / self.Power ^2)

The problem is, it keeps setting the angle to zero.

Anyone know why this is happening?

I'm trying to get the AI to calculate the angle to aim the shot from the bottom right corner to the player, which is in the bottom left.

Comments

  • mu-kowAPPSmu-kowAPPS Member Posts: 233
    Why not use vector to angle?

    I use a lot of rotations in my game.

    I have never used anything similar to the function you just stated
  • OkyshoOkysho Member Posts: 158
    Sorry, that's not an gamesalad function, it's an actual physics function to find an angle. I've plugged that formula into the vector angle behaviour. That's where I'm getting my error
  • mu-kowAPPSmu-kowAPPS Member Posts: 233
    Are you trying to get super elevation? I mean it compensates for the falling of the ball due to gravity?
  • OkyshoOkysho Member Posts: 158
    T-shirtbooth to the rescue!!!

    Actually for the first time, this didn't really help... See I'm trying to create a CPU AI to calculate where the player is and form an arc based on that. In this case, there's no mouse x or mouse y (used in the orbz demo) for the CPU to get since it's auto aiming for the player, the playing isn't aiming the CPU
  • mu-kowAPPSmu-kowAPPS Member Posts: 233
    I havnt seen orbz demo, but can't you just replace mouse.x y with player.x y. Im sure if you tinker with what is in that demo, u will be able to make it work.
  • RThurmanRThurman Member, Sous Chef, PRO Posts: 2,881
    My guess would be that its the asin() function that is giving you a NAN error. The numbers within the asin() must evaluate to something between -1 and +1.

    Try testing out the expression with numbers that you know will work and then see if you get the correct result. (For example, I just plugged in "DistanceFrom = 200" and "Power = 100" into your equation and got a result of 5.65742. Do you get the same?
  • OkyshoOkysho Member Posts: 158
    Odd... that's an actual physics formula so it should work. power is the initial velocity and distanceFrom is the distance between the two players. To be honest though there could be a unit miscalculation...
  • RThurmanRThurman Member, Sous Chef, PRO Posts: 2,881
    Yes, the formula calculates the angle that the canon needs to be at in order to hit the target (given distance and velocity). The formula does work (as you have it). I really think its the values that you are giving it, either you are going to need to drop gravity "9.81" to a fraction (like .981) or you need to make sure that (gravity*distance/power^2) always evaluates to a fraction.

    Try plugging in the numbers I gave you and see if you get the same result.
  • OkyshoOkysho Member Posts: 158
    Unless I put it in wrong, I get something like 0.01 (rounded up) by punching in our demo numbers and changing the gravity to 0.981, However in Game Salad this still doesn't work
  • RThurmanRThurman Member, Sous Chef, PRO Posts: 2,881
    Here is what I did. I created a new game and made three game attributes (all real), angleOfTrajectory, distanceFrom, and Power
    I put the following behaviors in an actor --
    Change Attribute: self.distanceFrom To: 200
    Change Attribute: self.Power To: 100
    Change Attribute: self.angleOfTrajectory To: (1/2)*asin(9.81* self.distanceFrom / self.Power ^2)
    Display Text: self.angleOfTrajectory

    I get 5.65742 in the display text.

    If I change the angleOfTrajectory equation by removing the asin() function so that it reads: (.981* self.distanceFrom / self.Power ^2)
    I get .01962

    If I change the angleOfTrajectory equation to: (.981* self.distanceFrom / self.Power ^2)
    I get 1.12422

    Are you getting similar numbers?
  • OkyshoOkysho Member Posts: 158
    This is a bit emberassing to admit, but the main reason for the problem was that my global playerX was actually a boolean rather than a real...

    That being said a problem still remains. The distance between my two players is around 2000, now the CPU cannon's angle is practically straight up in the air, so there's still something wrong with my numbers. It might help if I provide some more data.

    My stage is 2400px so the distance between the two cannons is around 2000px. I currently have the power set to 600 for both cannons and the gravity on the projectile is 120.

    Changing the gravity to 120, however makes the CPU cannon spin until the cows come home, never reaching an angle, presumably because it's huge.
  • OkyshoOkysho Member Posts: 158
    I spent a good chunk of last night trying to get this physics formula to work...

    You're a miracle worker TSB seriously! I tried this before when mu-kow suggested switching the two values, but it didn't work for some reason. Maybe I just needed sleep...

    Thanks again.
  • cbtcbt Member Posts: 644
    Is it working now?
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