Quaternion rotations and gimble lock

Newbie & Debugging Questions
#1

Hi, I’ve been trying to implement a camera class for a couple of weeks now ive finally got something thats mostly working using quaternions for rotation and vectors for movement, but I think im suffering from gimble lock. The more i turn to the side the less height i can acheive turning upwards. Im fairly certain the vector section is correct and is mostly independant from the rotation.

Heres my code for the rotation


public void updateCamera()
{
	Quat4f rotation = new Quat4f();
		
	AxisAngle4f axisAngleX = new AxisAngle4f(cameraX.x, cameraX.y, cameraX.z, (float)Math.toRadians(angleX));
	AxisAngle4f axisAngleY = new AxisAngle4f(cameraY.x, cameraY.y, cameraY.z, (float)Math.toRadians(angleY));
		
	Quat4f quatXRotation = new Quat4f();
	Quat4f quatYRotation = new Quat4f();
		
	quatXRotation.set(axisAngleX);
	quatYRotation.set(axisAngleY);
		
	rotation.mul(quatYRotation, quatXRotation);
	rotation.normalize();
	
	Matrix4f newViewMatrix = new Matrix4f();
	newViewMatrix.set(rotation);
	newViewMatrix.transpose();
		
	float[] rotationMatrixArray = new float[]
	{
	newViewMatrix.m00, newViewMatrix.m01, newViewMatrix.m02, 0,
	newViewMatrix.m10, newViewMatrix.m11, newViewMatrix.m12, 0,
	newViewMatrix.m20, newViewMatrix.m21, newViewMatrix.m22, 0,
	 0, 0, 0, 1
	};

		gl.glLoadIdentity();
		glu.gluPerspective(60.0, 800/600, 2.0, 500.0f);
		
		gl.glTranslatef(cameraPosition.x, cameraPosition.y, cameraPosition.z);
		gl.glMultMatrixf(rotationMatrixArray);
	}

Am i doing something completely wrong? Or do i need to approach this from a different angle.

#2

You would probably be better served by asking this question in one of the OpenGL forums here.

#3

AIUI the whoel point of Quaternions is that they don’t suffer from gimble lock.

As this is a heavy 3D math question I would defintiely ask it in one of the 3D forums (JOGL or Java3D)

#4

hey arthor,

what are the values for the vectors cameraX and cameraY? Simply, the axes <1,0,0>, <0,1,0>?
and do you change angleX/angleY on key strokes?

further, what is ment by ‘The more i turn to the side the less height i can acheive turning upwards’?
Rotating around the y-axis, right?

#5

Jeff is right if the Quaternion is used to represent an orientation. On the surface, it appears that the quaternions may be used to represent axis rotations. I included an overview of Java 3D quanternions in this article that might prove useful (http://jdj.sys-con.com/read/99792.htm). The quaternions are covered in the section entitled ‘Slicker than Euler’ on page 3.

Mike

#6

Thanks for the interest, as sugessted ive posted again in one of the 3d forums, JOGL to be specific, hopefully that is a better place for the question. Ive also answered some of the questions asked in the new post

http://www.java-gaming.org/forums/index.php?topic=12801.0