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Rotate3dAnimation

/**
 * An animation that rotates the view on the Y axis between two specified
 * angles. This animation also adds a translation on the Z axis (depth) to
 * improve the effect.
 */
public class Rotate3dAnimation extends Animation
{
    private final float mFromDegrees;
    private final float mToDegrees;
    private final float mCenterX;
    private final float mCenterY;
    private final float mDepthZ;
    private final boolean mReverse;
    private Camera mCamera;

    /**
     * Creates a new 3D rotation on the Y axis. The rotation is defined by its
     * start angle and its end angle. Both angles are in degrees. The rotation
     * is performed around a center point on the 2D space, definied by a pair of
     * X and Y coordinates, called centerX and centerY. When the animation
     * starts, a translation on the Z axis (depth) is performed. The length of
     * the translation can be specified, as well as whether the translation
     * should be reversed in time.
     * 
     * @param fromDegrees
     *            the start angle of the 3D rotation
     * @param toDegrees
     *            the end angle of the 3D rotation
     * @param centerX
     *            the X center of the 3D rotation
     * @param centerY
     *            the Y center of the 3D rotation
     * @param reverse
     *            true if the translation should be reversed, false otherwise
     */
    public Rotate3dAnimation(float fromDegrees, float toDegrees, float centerX, float centerY, float depthZ, boolean reverse)
    {
        mFromDegrees = fromDegrees;
        mToDegrees = toDegrees;
        mCenterX = centerX;
        mCenterY = centerY;
        mDepthZ = depthZ;
        mReverse = reverse;
    }

    @Override
    public void initialize(int width , int height , int parentWidth , int parentHeight)
    {
        super.initialize(width, height, parentWidth, parentHeight);
        mCamera = new Camera();
    }

    @Override
    protected void applyTransformation(float interpolatedTime , Transformation t)
    {
        final float fromDegrees = mFromDegrees;
        float degrees = fromDegrees + ((mToDegrees - fromDegrees) * interpolatedTime);
        final float centerX = mCenterX;
        final float centerY = mCenterY;
        final Camera camera = mCamera;
        final Matrix matrix = t.getMatrix();
        camera.save();
        if (mReverse)
        {
            camera.translate(0.0f, 0.0f, mDepthZ * interpolatedTime);
        }
        else
        {
            camera.translate(0.0f, 0.0f, mDepthZ * (1.0f - interpolatedTime));
        }
        camera.rotateY(degrees);
        camera.getMatrix(matrix);
        camera.restore();
        matrix.preTranslate(-centerX, -centerY);
        matrix.postTranslate(centerX, centerY);
    }
}