Converting a Javascript Drag and Drop script to C#

Question

I'm trying to figure out how to correctly convert this piece of Javascript to C#. I'm still pretty new to programming, I do have some experience though I can't figure this one out, because I get boatloads of errors I don't understand, even when trying to find these on google.

Here is the original:

 var normalCollisionCount = 1;
 var moveLimit = .5;
 var collisionMoveFactor = .01;
 var addHeightWhenClicked = 0.0;
 var freezeRotationOnDrag = true;
 var cam : Camera;
 private var myRigidbody : Rigidbody;
 private var myTransform : Transform;
 private var canMove = false;
 private var yPos : float;
 private var gravitySetting : boolean;
 private var freezeRotationSetting : boolean;
 private var sqrMoveLimit : float;
 private var collisionCount = 0;
 private var camTransform : Transform;
 
 function Start () {
     myRigidbody = rigidbody;
     myTransform = transform;
     if (!cam) {
         cam = Camera.main;
     }
     if (!cam) {
         Debug.LogError("Can't find camera tagged MainCamera");
         return;
     }
     camTransform = cam.transform;
     sqrMoveLimit = moveLimit * moveLimit;   // Since we're using sqrMagnitude, which is faster than magnitude
 }
 
 function OnMouseDown () {
     canMove = true;
     myTransform.Translate(Vector3.up*addHeightWhenClicked);
     gravitySetting = myRigidbody.useGravity;
     freezeRotationSetting = myRigidbody.freezeRotation;
     myRigidbody.useGravity = false;
     myRigidbody.freezeRotation = freezeRotationOnDrag;
     yPos = myTransform.position.y;
 }
 
 function OnMouseUp () {
     canMove = false;
     myRigidbody.useGravity = gravitySetting;
     myRigidbody.freezeRotation = freezeRotationSetting;
     if (!myRigidbody.useGravity) {
         myTransform.position.y = yPos-addHeightWhenClicked;
     }
 }
 
 function OnCollisionEnter () {
     collisionCount++;
 }
 
 function OnCollisionExit () {
     collisionCount--;
 }
 
 function FixedUpdate () {
     if (!canMove) return;
    
     myRigidbody.velocity = Vector3.zero;
     myRigidbody.angularVelocity = Vector3.zero;
     myTransform.position.y = yPos;
     var mousePos = Input.mousePosition;
     var move = cam.ScreenToWorldPoint(Vector3(mousePos.x, mousePos.y, camTransform.position.y - myTransform.position.y)) - myTransform.position;
     move.y = 0.0;
     if (collisionCount > normalCollisionCount) {
         move = move.normalized*collisionMoveFactor;
     }
     else if (move.sqrMagnitude > sqrMoveLimit) {
         move = move.normalized*moveLimit;
     }
    
     myRigidbody.MovePosition(myRigidbody.position + move);
 }

I've done some translating myself first, and then got some help but we couldnt figure it out together either

Here is the translation:

 using UnityEngine;
 using System.Collections;
 
 public class Vertaling : MonoBehaviour {
 public int normalCollisionCount= 1;
 
 public float moveLimit= 0.5f;
 public float collisionMoveFactor= 0.01f;
 public float addHeightWhenClicked= 0.0f;
 public bool freezeRotationOnDrag= true;
 Camera cam;
 private Rigidbody myRigidbody;
 private Transform myTransform;
 private bool canMove= false;
 private float yPos;
 private bool  gravitySetting;
 private bool  freezeRotationSetting;
 private float sqrMoveLimit;
 private int collisionCount= 0;
 private Transform camTransform;
 
 void  Start (){
     myRigidbody = rigidbody;
     myTransform = transform;
     if (!cam) {
         cam = Camera.main;
     }
     if (!cam) {
         Debug.LogError("Can't find camera tagged MainCamera");
         return;
     }
     camTransform = cam.transform;
     sqrMoveLimit = moveLimit * moveLimit;   
 }
 
 void  OnMouseDown (){
     canMove = true;
     myTransform.Translate(Vector3.up*addHeightWhenClicked);
     gravitySetting = myRigidbody.useGravity;
     freezeRotationSetting = myRigidbody.freezeRotation;
     myRigidbody.useGravity = false;
     myRigidbody.freezeRotation = freezeRotationOnDrag;
     yPos = myTransform.position.y;
 }
 
 void  OnMouseUp (){
     canMove = false;
     myRigidbody.useGravity = gravitySetting;
     myRigidbody.freezeRotation = freezeRotationSetting;
     if (!myRigidbody.useGravity) {
         myTransform.position.y = yPos-addHeightWhenClicked;
     }
 }
 
 void  OnCollisionEnter (){
     collisionCount++;
 }
 
 void  OnCollisionExit (){
     collisionCount--;
 }
 
 void  FixedUpdate (){
     if (!canMove) return;
    
     myRigidbody.velocity = Vector3.zero;
     myRigidbody.angularVelocity = Vector3.zero;
     myTransform.position.y = yPos;
     var mousePos= Input.mousePosition;
     var move= cam.ScreenToWorldPoint(Vector3(mousePos.x, mousePos.y, camTransform.position.y - myTransform.position.y)) - myTransform.position;
     move.y = 0.0f;
     if (collisionCount > normalCollisionCount) {
         move = move.normalized*collisionMoveFactor;
     }
     else if (move.sqrMagnitude > sqrMoveLimit) {
         move = move.normalized*moveLimit;
     }
    
     myRigidbody.MovePosition(myRigidbody.position + move);
 }
 }

I hope some of you guys have the time and patience to help me. Thanks in advance!

Answer 1

Errors found:
1- You must use a new keyword before a Vector3 constructor (constants like Vector3.up don't need it);
2- You can read position.y, but not write to it. position is a property of Transform, and C# doesn't allow writing to individual components of a property - you must copy the property to an auxiliary variable, modify the component and store the variable back in the property.
Javascript takes care of these minor details for us, but C# is more cranky (too cranky for a script language, in my opinion), and its error messages claim for a Rosetta stone to be deciphered. I fixed these errors in the code below:

... void OnMouseUp (){ canMove = false; myRigidbody.useGravity = gravitySetting; myRigidbody.freezeRotation = freezeRotationSetting; if (!myRigidbody.useGravity) { // you can't set y alone in the property position: Vector3 temp = myTransform.position; temp.y = yPos-addHeightWhenClicked; myTransform.position = temp; } }

void OnCollisionEnter (){ collisionCount++; }

void OnCollisionExit (){ collisionCount--; }

void FixedUpdate (){ if (!canMove) return;

 myRigidbody.velocity = Vector3.zero;
 myRigidbody.angularVelocity = Vector3.zero;
 // the same problem here:
 Vector3 temp = myTransform.position;
 temp.y = yPos;
 myTransform.position = temp;
 var mousePos= Input.mousePosition;
 // you must use new when constructing a Vector3:
 var move= cam.ScreenToWorldPoint(new Vector3(mousePos.x, mousePos.y, camTransform.position.y - myTransform.position.y)) - myTransform.position;
 move.y = 0.0f; // move is a variable, not a property, thus this is ok
 if (collisionCount > normalCollisionCount) {
     move = move.normalized*collisionMoveFactor;
 }
 else if (move.sqrMagnitude > sqrMoveLimit) {
     move = move.normalized*moveLimit;
 }
 myRigidbody.MovePosition(myRigidbody.position + move);

} } Another common problem in C# is GetComponent: you must use GetComponent<Rigidbody>() instead of GetComponent(Rigidbody) in javascript. Javascript supports both versions, but C# only accepts the first one.

Converting a Javascript Drag and Drop script to C#

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