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## [SOLVED] Relative cam movement and momentum on arbitrary surface

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### #1Neoshaman  Members

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Posted 06 April 2013 - 12:32 AM

Hello!

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 camera code

using UnityEngine;
using System.Collections;

{
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);
}
}



The movement code

using UnityEngine;
using System.Collections;

public class MovementController : MonoBehaviour
{
public float
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;
}

}



Demo:

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

Edited by Neoshaman, 08 April 2013 - 04:49 PM.

>>>>>>>>>>>>>>>be goodbe evilbut do it WELL>>>>>>>>>>>>>>>

### #2Neoshaman  Members

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Posted 06 April 2013 - 04:22 PM

I have made some package for those who want to tweak the code (unity3D 3.x)

Zipped project
https://dl.dropbox.com/u/24530447/sonic%20engine/lite%20sonic%20engine.rar

Unitypackage
https://dl.dropbox.com/u/24530447/LiteSonicEngine5a.unitypackage

>>>>>>>>>>>>>>>be goodbe evilbut do it WELL>>>>>>>>>>>>>>>

### #3Neoshaman  Members

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Posted 08 April 2013 - 04:47 PM

>>>>>>>>>>>>>>>be goodbe evilbut do it WELL>>>>>>>>>>>>>>>

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