bullet rotation as its affected by gravity

Question

Hi, i am trying to get a bullet to rotate as it moves and is affected by gravity. So if the bullet speed in 0m/s it will just rotate 90degrees and fall straight down. My plan was to "make" a triangle of the "start" and "end" position of the bullet, ofc the start and end position changes alot during the bullets flight. alt text

So my code looks like this

 tempDistance = Vector3.Distance(startV,endV);
 angle = Mathf.Rad2Deg * (Mathf.Asin(hightdecrease/tempDistance));
 Vector3 test = new Vector3(angle,0,0);
 transform.Rotate(test);

highdecrease is B in the picture above and i think tempDistance will be C.

But this doesn´t seems to work at all, i get very strange angles. Is the math correct?

Answer 1

Best Answer

Answer by Common_Horse · Jun 08, 2012 at 10:19 AM

You could try this:

 //This would be the maximum speed of you bullet
 float maxSpeed = 900;
 
 //This is where the bullet was last frame
 Vector3 lastPos;
 
 void Update () {
 //Find the velocity in m/s
 float velocity = (lastPos - transform.position)/Time.deltaTime;
 
 //Set up a ratio that will be used to rotate the bullet. If the velocity is maxSpeed, then the rotation will be 0 (forward, else it will rotate towards facing down (Assuming that +Z is your forward axis)
 
 transform.eulerAngles = new Vector3(velocity/maxSpeed * 90, transform.eulerAngles.y, 0);
 
 //Set lastPos so we can get the velocity next frame!
 
 lastPos = transform.Position;
 
 }

Very rough, but if you implement code like this, it should do what you asked!

-AJ

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Answer 2

Answer by Eqric · Jun 08, 2012 at 10:30 AM

Thanks mate, i give this a try!

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Common_Horse · Jun 08, 2012 at 10:50 AM 0

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bullet rotation as its affected by gravity

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