Line-link puzzle example

gistfile1.txt

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class TestCollider : MonoBehaviour
{
    static bool isDragging;
    static TestCollider lastDragNode;
    static List<TestCollider> draggedNodes = new List<TestCollider>();

    public byte nodeType = 0;

    private void OnMouseDrag()
    {
        if (lastDragNode == null)
        {
            draggedNodes.Add(this);
            lastDragNode = this;
        }
    }

    private void OnMouseOver()
    {
        if (lastDragNode == null || lastDragNode == this)
            return;

        var tempLastDragNodeLayer = lastDragNode.gameObject.layer;
        lastDragNode.gameObject.layer = 2; // Set layer to ignore raycast
        var result = Physics2D.Linecast(lastDragNode.transform.position, transform.position);
        if (lastDragNode.nodeType == nodeType &&
            result.collider.gameObject == gameObject /* Check current node is not obstructed by other node types */)
        {
            lastDragNode.gameObject.layer = tempLastDragNodeLayer;
            draggedNodes.Add(this);
            lastDragNode = this;
        }
        else
        {
            lastDragNode.gameObject.layer = tempLastDragNodeLayer;
        }
    }

    private void OnMouseUp()
    {
        if (draggedNodes.Count > 1)
        {
            // Collect score
            int score = draggedNodes.Count * 10;
            Debug.Log("Score += " + score + " nodeType = " + lastDragNode.nodeType);
            // Clear all dragged nodes
            for (int i = draggedNodes.Count - 1; i >= 0; --i)
            {
                Destroy(draggedNodes[i].gameObject);
            }
        }
        draggedNodes.Clear();
        lastDragNode = null;
    }
}