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I have been working on a game for quite long, think sonic classic physics in 3D or tony hawk psx, with unity3D. However I'm stuck at the most fundamental aspect of movement.

The requirement is that I need to move the character in mario 64 fashion (or sonic adventure) aka relative cam input:

  1. the camera's forward direction always point input forward the screen, left or right input point toward left or right of the screen.

  2. when input are resting, the camera direction is independent from the character direction and the camera can orbit the character

  3. when input are pressed the character rotate itself until his direction align with the direction the input is pointing at.

It's super easy to do as long your movement are parallel to the global horizontal (or any world axis). However when you try to do this on arbitrary surface (think moving along complex curved surface) with the character sticking to the surface normal (basically moving on wall and ceiling freely), it seems harder. What I want is to achieve the same finesse of movement than in mario but on arbitrary angled surfaces. There is more problem (jumping and transitioning back to the real world alignment and then back on a surface while keeping momentum) but so far I didn't even take off the basics.

So far I have accomplish moving along the curved surface and the relative cam input, but for some reason direction fail all the time (point number 3, the character align slowly to the input direction).

Do you have an idea how to achieve that?

Here is the code and some demo so far:

The demo:

https://dl.dropbox.com/u/24530447/flash%20build/litesonicengine/LiteSonicEngine5.html

Camera code:

using UnityEngine;
using System.Collections;

    public class CameraDrive : MonoBehaviour
    {
        public GameObject
            targetObject;

        public Transform
            camPivot,
            camTarget,
            camRoot,

            relcamdirDebug;

        float
            rot = 0;
    //----------------------------------------------------------------------------------------------------------
        void Start()
        {
            this.transform.position = targetObject.transform.position;
            this.transform.rotation = targetObject.transform.rotation;
        }

        void FixedUpdate()
        {        
        //the pivot system
            camRoot.position    = targetObject.transform.position;

        //input on pivot orientation
            rot = 0;
            float mouse_x        = Input.GetAxisRaw( "camera_analog_X" );                //
            rot                 = rot + ( 0.1f * Time.deltaTime * mouse_x );            //
            wrapAngle( rot );                                                            //

        //when the target object rotate, it rotate too, this should not happen


            UpdateOrientation(this.transform.forward,targetObject.transform.up);

            camRoot.transform.RotateAround(camRoot.transform.up,rot);

        //debug the relcam dir
                RelativeCamDirection()
                ;

        //this camera
            this.transform.position    = camPivot.position;                            //set the camera to the pivot
            this.transform.LookAt( camTarget.position );                            //
        }
    //----------------------------------------------------------------------------------------------------------
        public float wrapAngle ( float Degree )
        {
            while (Degree < 0.0f)
            {
                Degree = Degree + 360.0f;
            }
            while (Degree >= 360.0f)
            {
                Degree = Degree - 360.0f;
            }
            return Degree;
        }

        private void UpdateOrientation( Vector3 forward_vector, Vector3 ground_normal )
        {
            Vector3
                projected_forward_to_normal_surface = forward_vector - ( Vector3.Dot( forward_vector, ground_normal ) ) * ground_normal;

            camRoot.transform.rotation = Quaternion.LookRotation( projected_forward_to_normal_surface, ground_normal );
        }

        float GetOffsetAngle( float targetAngle, float DestAngle )
        {
                return ((targetAngle - DestAngle + 180)% 360)  - 180;
        }
    //----------------------------------------------------------------------------------------------------------
        void OnDrawGizmos()
        {
            Gizmos.DrawCube(
                camPivot.transform.position,
            new Vector3(1,1,1)
                );

            Gizmos.DrawCube(
                camTarget.transform.position,
            new Vector3(1,5,1)
                );

            Gizmos.DrawCube(
                camRoot.transform.position,
            new Vector3(1,1,1)
                );
        }

        void OnGUI()
        {
            GUI.Label(new Rect(0,80,1000,20*10), "targetObject.transform.up : " + targetObject.transform.up.ToString());
            GUI.Label(new Rect(0,100,1000,20*10), "target euler : " + targetObject.transform.eulerAngles.y.ToString());
            GUI.Label(new Rect(0,100,1000,20*10), "rot : " + rot.ToString());

        }
    //----------------------------------------------------------------------------------------------------------
        void RelativeCamDirection()
        {

            float
                input_vertical_movement     = Input.GetAxisRaw( "Vertical" ),
                input_horizontal_movement     = Input.GetAxisRaw( "Horizontal" );

            Vector3
                relative_forward     = Vector3.forward,
                relative_right         = Vector3.right,

                relative_direction    =
                    ( relative_forward    * input_vertical_movement )
                    +
                    ( relative_right    * input_horizontal_movement )
                    ;

            MovementController MC = targetObject.GetComponent<MovementController>();

            MC.motion = relative_direction.normalized * MC.acceleration * Time.fixedDeltaTime;

            MC.motion = this.transform.TransformDirection( MC.motion );

            //MC.transform.Rotate(Vector3.up, input_horizontal_movement * 10f * Time.fixedDeltaTime);    
        }
    }

Mouvement code:

using UnityEngine;
using System.Collections;

public class MovementController : MonoBehaviour
{
    public float
        deadZoneValue = 0.1f,
        angle,
        acceleration  = 50.0f;
    public Vector3
        motion ;

//--------------------------------------------------------------------------------------------    
    void OnGUI()
    {
        GUILayout.Label( "transform.rotation : " + transform.rotation );
        GUILayout.Label( "transform.position : " + transform.position );
        GUILayout.Label( "angle : " + angle );
    }

    void FixedUpdate ()
    {

        Ray
            ground_check_ray = new Ray( gameObject.transform.position, -gameObject.transform.up );
        RaycastHit
            raycast_result;
        Rigidbody
            rigid_body = gameObject.rigidbody;

        if ( Physics.Raycast( ground_check_ray, out raycast_result ) )
        {
            Vector3
                next_position;

            //UpdateOrientation( gameObject.transform.forward, raycast_result.normal );
            UpdateOrientation( gameObject.transform.forward, raycast_result.normal );    
            next_position = GetNextPosition( raycast_result.point );
            rigid_body.MovePosition( next_position );
        }
    }
//--------------------------------------------------------------------------------------------    


    private void UpdateOrientation( Vector3 forward_vector, Vector3 ground_normal )
    {
        Vector3
            projected_forward_to_normal_surface = forward_vector - ( Vector3.Dot( forward_vector, ground_normal ) ) * ground_normal;

        transform.rotation = Quaternion.LookRotation( projected_forward_to_normal_surface, ground_normal );
    }

    private Vector3 GetNextPosition( Vector3 current_ground_position )
    {
        Vector3
            next_position;

//        //--------------------------------------------------------------------
//        angle = 0;
//        Vector3 dir = this.transform.InverseTransformDirection(motion);
//        angle = Vector3.Angle(Vector3.forward, dir);// * 1f * Time.fixedDeltaTime;
//        
//        if(angle > 0) this.transform.Rotate(0,angle,0);
//        //--------------------------------------------------------------------


        next_position =
            current_ground_position +
            gameObject.transform.up * 0.5f
                + motion
                ;

        return next_position;
    }

}

Some observation:

I have the correct input, I have the correct translation in the camera direction ... but whenever I attempt to slowly lerp the direction of the character in direction of the input, all I get is wild spin! Sad

Also discovered that strafing to the right (immediately at the beginning without moving forward) has major singularity trapping on the equator!!

I'm totally lost and crush (I have already done a much more featured version which fail at the same aspect)

share|improve this question

2 Answers 2

It's solved now! See the comment above to have the details!

Now another problem is to build in momentum ... the fun only begin lol

New Build: https://dl.dropbox.com/u/24530447/flash%20build/litesonicengine/LiteSonicEngine6.html Arrow to move, mouse to turn camera around

Movement code (lerp commented)

using UnityEngine;
using System.Collections;

public class MovementController : MonoBehaviour
{
    public float
        deadZoneValue = 0.1f,
        angle,
        acceleration  = 50.0f;
    public Vector3 
        motion ;
    public Vector3 
        ground_direction ;

//--------------------------------------------------------------------------------------------  
    void OnGUI()
    {
        GUILayout.Label( "transform.rotation : " + transform.rotation );
        GUILayout.Label( "transform.position : " + transform.position );
        GUILayout.Label( "angle : " + angle );
        GUILayout.Label( "ground_direction : " + ground_direction );
        GUILayout.Label( "motion : " + ground_direction );
    }

    void FixedUpdate ()
    {

        Ray
            ground_check_ray = new Ray( gameObject.transform.position, -gameObject.transform.up );
        RaycastHit 
            raycast_result;
        Rigidbody
            rigid_body = gameObject.rigidbody;

        if ( Physics.Raycast( ground_check_ray, out raycast_result ) )
        {
            Vector3
                next_position;

            //UpdateOrientation( gameObject.transform.forward, raycast_result.normal );
            UpdateOrientation( gameObject.transform.forward, raycast_result.normal );   
            next_position = GetNextPosition( raycast_result.point );
            rigid_body.MovePosition( next_position );
            ground_direction = raycast_result.normal;
        }
    }
//--------------------------------------------------------------------------------------------  


    private void UpdateOrientation( Vector3 forward_vector, Vector3 ground_normal )
    {
        Vector3
            projected_motion_to_normal_surface = motion - ( Vector3.Dot( motion, ground_normal ) ) * ground_normal;

        Quaternion target;
        if (motion.sqrMagnitude > 0)
        {
            target = Quaternion.LookRotation( projected_motion_to_normal_surface, ground_direction );
        }
        else
        {
            target = Quaternion.LookRotation( transform.forward, ground_direction );
        }
        transform.rotation  = target;//Quaternion.Slerp( transform.rotation, target, 0.1f );
        //transform.rotation = Quaternion.LookRotation( projected_forward_to_normal_surface, ground_normal );

        Debug.DrawRay(this.transform.position,motion*10,Color.yellow,0.0f,false);
    }

    private Vector3 GetNextPosition( Vector3 current_ground_position )
    {
        Vector3
            next_position;

//      //--------------------------------------------------------------------
//      angle = 0;
//      Vector3 dir = this.transform.InverseTransformDirection(motion);
//      angle = Vector3.Angle(Vector3.forward, dir);// * 1f * Time.fixedDeltaTime;
//      
//      if(angle > 0) this.transform.Rotate(0,angle,0);
//      //--------------------------------------------------------------------


        next_position = 
            current_ground_position + 
            gameObject.transform.up * 0.5f
                + motion
                ;

        return next_position;
    }

}

Camera code

using UnityEngine;
using System.Collections;

public class CameraDrive : MonoBehaviour
{
    public GameObject
        targetObject;

    public Transform
        camPivot,
        camTarget,
        camRoot,

        relcamdirDebug;

    float
        rot = 0;
//----------------------------------------------------------------------------------------------------------
    void Start()
    {
        this.transform.position = targetObject.transform.position;
        this.transform.rotation = targetObject.transform.rotation;
    }

    void FixedUpdate()
    {       
    //the pivot system
        camRoot.position    = targetObject.transform.position;

    //input on pivot orientation
        rot = 0;
        float mouse_x       = Input.GetAxisRaw( "camera_analog_X" );                //
        rot                 = rot + ( 0.1f * Time.deltaTime * mouse_x );            //
        wrapAngle( rot );                                                           //

    //when the target object rotate, it rotate too, this should not happen


        UpdateOrientation(this.transform.forward,targetObject.transform.up);

        camRoot.transform.RotateAround(camRoot.transform.up,rot);


    //this camera
        this.transform.position = camPivot.position;
    //set the camera to the pivot
        //Quaternion target = Quaternion.LookRotation(targetObject.transform.position - this.transform.position, targetObject.transform.up);

        //this.transform.rotation = Quaternion.Slerp(this.transform.rotation, target, 0.1f);

    //relcam dir
       RelativeCamDirection();

    this.transform.LookAt( camTarget.position );                            //
    }
//----------------------------------------------------------------------------------------------------------
    public float wrapAngle ( float Degree )
    {
        while (Degree < 0.0f)
        {
            Degree = Degree + 360.0f;
        }
        while (Degree >= 360.0f)
        {
            Degree = Degree - 360.0f;
        }
        return Degree;
    }

    private void UpdateOrientation( Vector3 forward_vector, Vector3 ground_normal )
    {
        Vector3
            projected_forward_to_normal_surface = forward_vector - ( Vector3.Dot( forward_vector, ground_normal ) ) * ground_normal;

        camRoot.transform.rotation = Quaternion.LookRotation( projected_forward_to_normal_surface, ground_normal );
    }

    float GetOffsetAngle( float targetAngle, float DestAngle )
    {
            return ((targetAngle - DestAngle + 180)% 360)  - 180; 
    }
//----------------------------------------------------------------------------------------------------------
    void OnDrawGizmos()
    {
        Gizmos.DrawCube(
            camPivot.transform.position,
        new Vector3(1,1,1)
            );

        Gizmos.DrawCube(
            camTarget.transform.position,
        new Vector3(1,5,1)
            );

        Gizmos.DrawCube(
            camRoot.transform.position,
        new Vector3(1,1,1)
            );
    }

    void OnGUI()
    {
        GUI.Label(new Rect(0,80,1000,20*10), "targetObject.transform.up : " + targetObject.transform.up.ToString());
        GUI.Label(new Rect(0,100,1000,20*10), "target euler : " + targetObject.transform.eulerAngles.y.ToString());
        GUI.Label(new Rect(0,100,1000,20*10), "rot : " + rot.ToString());

    }
//----------------------------------------------------------------------------------------------------------
    void RelativeCamDirection()
    {   
        Vector3
            relative_direction  = 
                ( Vector3.forward   * Input.GetAxisRaw( "Vertical" ) )
                + 
                ( Vector3.right     * Input.GetAxisRaw( "Horizontal" ) )
                ;

        MovementController MC = targetObject.GetComponent<MovementController>();

        Vector3 direction = relative_direction.normalized * MC.acceleration * Time.fixedDeltaTime;

        Vector3 abs_direction =  camRoot.transform.TransformDirection( direction );
        MC.motion = abs_direction;

        Debug.DrawRay (camRoot.position, camRoot.right,Color.red,0.0f,false);
        Debug.DrawRay (camRoot.position, camRoot.up,Color.green,0.0f,false);
        Debug.DrawRay (camRoot.position, camRoot.forward,Color.blue,0.0f,false);
        //MC.transform.Rotate(Vector3.up, input_horizontal_movement * 10f * Time.fixedDeltaTime);

    }
}
share|improve this answer

For the slerping, try someting as this (but only if your input vector is non-zero):

//MC.transform.Rotate(Vector3.up, input_horizontal_movement * 10f * Time.fixedDeltaTime);
Quaternion target = Quaternion.LookRotation( relative_direction, MC.transform.up );
MC.transform.rotation = Quaternion.slerp(MC.transform.rotation, target, 0.5);

For the singularity trapping: Why do you keep the movement vectors relative_forward and relative_right orientated as the camera? At the equator your movement vectors point in the same direction as your ground normal.

share|improve this answer
    
I have made a new demo with your suggestion, however spotting some function you use I knew about some problem before hand: dl.dropbox.com/u/24530447/flash%20build/litesonicengine/… The camera itself is not use for left or right, i use a root object that share the normal alignment of the character but free to rotate on the character's local Y. Normally right and forward are expressed on the same plane that the character, so I don't get why right does not work while forward does. –  user29244 Apr 6 '13 at 18:59
    
It does not work very well, plus the camera control has been negated for some reason :( –  user29244 Apr 6 '13 at 21:22
    
I have made some further package for those who want to try without copy pasting the code (unity 3.x) Zipped project dl.dropbox.com/u/24530447/sonic%20engine/… Unitypackage dl.dropbox.com/u/24530447/LiteSonicEngine5a.unitypackage –  user29244 Apr 6 '13 at 22:21
    
For me, the slerping of the character seems to work fine. Maybe you want to try a smaller slerping factor istead of 0.5? –  Dirk Apr 7 '13 at 18:04
    
I worked a little bit through your code and moved the slerp to the movement code: pastebin.com/F4rMAeft and pastebin.com/evCHMDpu . And I made the Camera to slerp its position as well. Thanks for the challenge :) –  Dirk Apr 7 '13 at 19:49

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