RollingCube.cs

/**
 * Move a cube by rolling in four directions.
 */

using UnityEngine;
using System.Collections;

public class RollingCube : MonoBehaviour {
	public float speed = 2;

	public Transform left, right, forward, back, allRotators;


	Quaternion rollRotation = Quaternion.Euler(new Vector3 (0, 0, 90));
	float progress;
	Quaternion startRotatorRotation, endRotatorRotation;

	public bool IsRolling {
		get { return transform.parent != null; }
	}

	void Reset () {
		// create all rotators (make sure, their x-axis is pointing toward the center of the cube)
		allRotators = new GameObject ("AllRotators").transform;
		allRotators.position = transform.position;

		left = CreateRotator ("Left", Vector3.left * 0.5f, Quaternion.identity);
		right = CreateRotator ("Right", Vector3.right * 0.5f, Quaternion.Euler(new Vector3(0, 180, 0)));
		back = CreateRotator ("Back", Vector3.back * 0.5f, Quaternion.Euler(new Vector3(0, 270, 0)));
		forward = CreateRotator ("Forward", Vector3.forward * 0.5f, Quaternion.Euler(new Vector3(0, 90, 0)));
	}

	Transform CreateRotator(string name, Vector3 pos, Quaternion rotation) {
		var go = new GameObject(name);
		pos += Vector3.down * 0.5f;

		var newTransform = go.transform;
		newTransform.SetParent(transform);
		newTransform.localPosition = pos;
		newTransform.rotation = rotation;
		newTransform.SetParent(allRotators);

		return newTransform;
	}

	void FixedUpdate () {
		if (!IsRolling) {
			// not rolling -> We can start rolling
			var horizontal = Input.GetAxis ("Horizontal");
			var vertical = Input.GetAxis ("Vertical");
			if (horizontal < 0) {
				StartRoll (left);
			}
			else if (horizontal > 0) {
				StartRoll (right);
			}
			else if (vertical < 0) {
				StartRoll (back);
			}
			else if (vertical > 0) {
				StartRoll (forward);
			}
		} else {
			// keep on rolling!
			UpdateRoll();
		}
	}


	void StartRoll(Transform rotator) {
		// add cube to rotator
		transform.SetParent (rotator);

		// set start and end rotation
		startRotatorRotation = rotator.rotation;
		endRotatorRotation = rotator.rotation * rollRotation;
	}


	void UpdateRoll() {
		// update progress (let progress go from 0 to 1 in 1/speed seconds)
		progress = Mathf.Min(1, progress + speed * Time.deltaTime);

		// interpolate rotation between start and end rotations
		var progressTransform = transform.parent.transform;
		progressTransform.rotation = Quaternion.Lerp(startRotatorRotation, endRotatorRotation, progress);

		if (progress >= 1) {
			// finished rolling
			EndRoll();
		}
	}


	void EndRoll() {
		// move all rotators
		allRotators.position = transform.position;

		// reset progress & rotator's rotation
		var rotator = transform.parent;
		rotator.rotation = startRotatorRotation;
		progress = 0;


		// remove from parent
		transform.SetParent (null);
	}
}