# Acceleration and movement problem

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I'm trying to make a game with a space ship that has the same physics as teh asteroids ship. you can rotate the ship and accelerate towards the direction the ship is pointing and no air resistance to slow the ship down. If you want to stop, you need to accelerate in the opposite direction of your movement. Anyway, everything works ok except for one thing: I don't have a max_velocity value. That is, i haven't coded a speed limit for the ship. Why I haven't done that is because I don't know how. The game is 2D and programmed in Java using Jogl. A textured polygon is the ship and I rotate it using glrotatef(). I have a vel_x and a vel_y value which keeps track of the velocity of the ship on each axis. I also have a variable angle, which keeps track of where the ship is pointing so I know in which direction to accelerate the ship when the user presses the up-arrow. Anyone have any clue how I can implement a speed limit? Thanx a lot

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if (vel_x*vel_x)+(vel_y*vel_y)>(maxspeed*maxspeed)
{
vel_x=vel_x*maxspeed/sqrt((vel_x*vel_x)+(vel_y*vel_y))
vel_y=vel_y*maxspeed/sqrt((vel_x*vel_x)+(vel_y*vel_y))
}

that way u "normalize" the velociti.. i think.. :P

is not the best... but i think it will work..

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Check 'math and physics' - I think there are (or were recently) some threads on this.

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thanx jyk,

the otehr thread solved the problem perfectly :)

cheers

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