koobas.hobune.stream
Moving an ob around a sphere
I would like to move an object (lets say a 2d triangle ) around a sphere. The following code results the triangle behave in a strange way.
void Update ()
{
if (Input.GetAxis ("Horizontal") > 0)
{
abs_rotation += 0.1f;
}
if (Input.GetAxis ("Horizontal") < 0)
{
abs_rotation -= 0.1f;
}
if (Input.GetAxis ("Vertical") > 0)
{
this.rigidbody.AddForce(this.transform.forward * 10);
Debug.Log("Up");
}
//I store the center of the sphere in a varriable
Vector3 spherePos = GameObject.Find("Sphere").transform.position;
//I calculate what would be the position of the object on the surface of the sphere
//Distance represents the radius of the sphere
Vector3 posVect = this.transform.position-spherePos;
posVect.Normalize();
posVect *= DISTANCE;
//I put my triangle to the right position and rotate i to the appropriate direction
this.transform.position = posVect;
this.transform.up = posVect;
this.transform.RotateAround(posVect,abs_rotation);
}
The problem is that my triangle behaves as if the bottom of the sphere was pulling it. Does anybody has any idea?
Is this your actual code? It should not even compile, since RotateAround requires 3 parameters: the center of rotation, the axis about which to rotate and the angle. RotateAround modifies the position and rotation of the rotating object so that it keeps facing the center - modifying these properties while rotating isn't a good idea, and may cause the weird behaviour you're describing. Another point: Find'ing an object every Update is terribly slow: Find it once at Start and save its position in a member variable instead. The code for rotating the object about the sphere could be something like this:
Vector3 center; // save the sphere center here
void Start(){ // Find sphere only once:
center = GameObject.Find("Sphere").transform.position;
}
void Update ()
{
if (Input.GetAxis ("Horizontal") > 0)
{
abs_rotation += 0.1f;
}
if (Input.GetAxis ("Horizontal") < 0)
{
abs_rotation -= 0.1f;
}
// rotate around sphere about world Y
this.transform.RotateAround(center, Vector3.up, abs_rotation);
}
Notice that abs_rotation is the rotation speed: this code rotates continuously around the sphere, and the left and right arrows just increase/decrease the speed. If you want to rotate only when these keys are pressed, change the code in Update to this:
void Update ()
{
float rotAngle = Input.GetAxis ("Horizontal") * 0.1f;
// rotate around sphere about world Y
this.transform.RotateAround(center, Vector3.up, rotAngle);
}
NOTE: I removed the Input.GetAxis("Vertical") code just because it was screwing up the formatting due to some mysterious and unknown reason - keep it in your code if you want.
First of all it compiles but I corrected the RotateAround function call as you suggested. If try the line "float rotAngle = Input.GetAxis ("Horizontal") * 0.1f;" nothing happens it doesn't rotate at all.
Sorry to be correct it rotates but only one unite an when I release the left or the right button it rotates back to the original direction automatically
You're right about RotateAround: there's an obsolete and undocumented version that accepts 2 arguments (although I could not understand what exactly it does). I tested my scripts and both did what I expected: abs_rotation behaved like the rotation speed in the first one, while the second one made the object rotate around the sphere only when the horizontal keys were pressed - but it didn't return to the original direction when they were released. $$anonymous$$aybe something else in your script is restoring the original rotation.
