Thread: cos & sin 2d movement

This is a bit of a maths question as much as java i think.
i have been stuck for about 3 weeks trying to make a silly racing car game. everything was going well apart from controlling the little things:



public void move()
{
//place checks in here as well and move from center of object


double radi = Math.toRadians(angle);// left over from one of many failed experiments

double x= Math.cos(angle);
double y= Math.sin(angle);

double fullspeed = speed * 1.5; //makes positive number change name

int centerX = x + 25;
int centerY = y + 25;

int addToX = (int)Math.round(fullspeed * x);
int addToY = (int)Math.round(y* fullspeed);

//this need to account for center
if(((x + addToX >= 50) && (x + addToX <=750)) && ((y + addToY >= 100) && (y + addToY <=550 )))
{
changePos(addToX, addToY);
}
}

private void changePos(int xMove, int yMove)
{
x = x + xMove;

y = y + yMove;
}

my cars are going all over the place. they start ok then start reversing and all sorts very un predictable.
when i do cos(270) on calculater i get 0 and sin(270) i get -1; cos(90) = 0 and sin(90) = 1. this is the pattern i want and expected.

but i am getting from the code:

Math.sin(270) = -0.1760459464712114
Math.cos(270) = 0.9843819506325049

on my calculater there is just "cos" & "sin" + "cosh" & "sinh" is this why and how do i get the results i need.

Have you read the API doc for those methods to see how they work?

Math.sin(270)

This suggests that you have not read the API doc. Is the 270 degrees or radians?

When I called toRadians() with degrees and used its value for the cos() and sin() methods, the results were as expected:

 System.out.println("cos(90)="+Math.cos(Math.toRadians(90)));

To see what the values are, write a loop that increments the degrees by 30 and goes from 0 to 360
and prints out three columns of degrees, sin and cos.