# Problem with Angle ( Mesh rotation ) [Resolve]

Hello all,

i’m trying to create a methode to rotate the viewDirection of a character smoothly. So i get the current viewRotation angle and increase or decrease the current angle until the final angle is reached. But sometimes the mesh turns on itself. I noticed that it’s happened when the angle sign change.

Moreover ,occasionally, the incrementation direction is wrong. So the mesh turn in the wrong direction and take the biggest angle. I don’t know why.

[java]float angle = FastMath.atan2(this.getViewDirection().x, this.getViewDirection().z); //The current view rotation angle

Vector2f walkTemp2 = new Vector2f(direction.z, direction.x);

float angle2 = walkTemp2.getAngle(); // The final view rotation angle

text = String.valueOf(tpf);

if (angle2 - angle > 0.1) {

angle += tpf0.01;

} else if(angle2 - angle < -0.1) {

angle -= tpf
0.01;

}

this.setViewDirection(new Vector3f(FastMath.sin(angle), 0, FastMath.cos(angle))); [/java]

Just use quaternions to rotate the vector:

https://wiki.jmonkeyengine.org/legacy/doku.php/jme3:math_for_dummies

Mmmm i change my method but it’s still bugged. Nothing has changed. But the tutorial is very clear and helpful. [java] float angle = FastMath.atan2(this.getViewDirection().x, this.getViewDirection().z);

Vector2f walkTemp2 = new Vector2f(direction.z, direction.x);

float angle2 = walkTemp2.getAngle();

text = String.valueOf(tpf);

Quaternion increment = new Quaternion();

if (angle2 - angle > 0.1) {

increment.fromAngleAxis(tpf0.01f, Vector3f.UNIT_Y);

} else if(angle2 - angle < -0.1) {

increment.fromAngleAxis(-tpf
0.01f,Vector3f.UNIT_Y);

}

this.setViewDirection(increment.mult(this.getViewDirection()));[/java]

I don’t know what can i do…

Here a diagram of my problem.

http://i.imgur.com/b7Lac.png

When the angle2 changes from 3.14 to -3.14 the character turns on itself.

I finally resolve my problem. (after searching throughout the internet)

[java] Quaternion increment1 = new Quaternion();

increment1.fromAngles(direction.x, 0, direction.z);

Quaternion increment2 = new Quaternion();

increment2.fromAngles(this.getViewDirection().x, 0, this.getViewDirection().z);

Quaternion increment3 = increment2.slerp(increment1, increment2, 0.99f);

float[] tempAngle = {0,0,0};

increment3.toAngles(tempAngle);

Vector3f finalDirection = new Vector3f(tempAngle, 0 , tempAngle);

this.setViewDirection(finalDirection);

this.setWalkDirection(finalDirection);[/java]

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