Thread: Ship Movement

Thanks for all the help until now!
Sorry, I forgot to tell that my game is 2D. Ok, I will post the piece of code that works for forward movement. In the code, x, y are the mouse coordinates. clWidth and clHeight is the sprite dimension, not very important. The number 4 is the maximum speed (will be a class attribute later).

Code:

// Critical region
WaitForSingleObject(clSemVel, INFINITE);
{
	// Update ship angle
	int base = x - clX-(clWidth/2); // base of triangle
	int height = y - clY-(clHeight/2); // height of triangle
	
	hipotenusa = sqrt(pow(base, 2) + pow(altura,2)); 

	clAngleY = height/hipotenusa;
	clTopYSpeed = clAngleY * 4;
	clAngleX =  base/hipotenusa;
	clTopXSpeed = clAngleX * 4;
}		
// End of critical region
ReleaseSemaphore(clSemVel, 1, NULL);

Now, I know that to do strafe, the Y speed must be equal to X speed, and X equal to Y, the problem is the sign of the variable, remembering that a negative value in Y, the object moves up, and negative in X the object moves left.

Code:

// Critical region
WaitForSingleObject(clSemVel, INFINITE);
{
	// User has pressed strafe
	int sign_y = 0;
	int sign_x = 0;
	if( strafe == LEFT ){
		sign_y = -1; //for example
		sign_x = 1; //for example too
	}
	if( strafe == RIGHT ){
		sign_y = 1; //another example
		sign_x = -1; //yes... example
	}
	cpTopYSpeed = sign_y * clTopXSpeed;
	cpTopXSpeed = sign_x * clTopYSpeed;
}		
// End of critical region
ReleaseSemaphore(clSemVel, 1, NULL);

The problem is that the sign calculation is too complex for my understanding. If anyone have a better idea ou the algoritm itself, I am grateful.