DiagramUtil.cs

using UnityEngine;
using System.Collections.Generic;

public class DiagramUtil
{
	
	
	public static Rect ShrinkRect (Rect rect, float dw, float dh)
	{
		return new Rect (rect.x + dw / 2, rect.y + dh / 2, rect.width - dw, rect.height - dh);
	}
	
	public static Rect ExpandRect (Rect rect, float dw, float dh)
	{
		return new Rect (rect.x - dw / 2, rect.y - dh / 2, rect.width + dw, rect.height + dh);
	}
	
	public static Rect TranslateRect(Rect rect, float dx, float dy){
		return new Rect (rect.x + dx, rect.y + dy, rect.width, rect.height);
	}
	
	public static Rect UnionRect (Rect rect, float x1, float y1)
	{
		if (x1 < rect.x) {
			rect.width += (rect.x - x1);
			rect.x = x1;
		} else {
			float right = rect.x + rect.width;
			if (x1 >= right) {
				right = x1 + 1;
				rect.width = right - rect.x;
			}
		}
		if (y1 < rect.y) {
			rect.height += (rect.y - y1);
			rect.y = y1;
		} else {
			float bottom = rect.y + rect.height;
			if (y1 >= bottom) {
				bottom = y1 + 1;
				rect.height = bottom - rect.y;
			}
		}
		return rect;

	}
	
	public static bool ContainsEdge (List<Vector2> positions, Vector2 point, int tolerance)
	{
		for (int i = 0; i< positions.Count -1; i++) {
			Vector2 position1 = positions [i];
			Vector2 position2 = positions [i + 1];
			if (ContainsSegment (position1.x,
                         position1.y, position2.x,
                         position2.y, point.x, point.y, tolerance)) {
				return true;
			}
		}          
		return false;
	}

	public static bool ContainsSegment (float x1, float y1, float x2, float y2,
               float px, float py, int tolerance)
	{
		/*
           * Point should be located inside Rectangle(x1 -+ tolerance, y1 -+
           * tolerance, x2 +- tolerance, y2 +- tolerance)
           */
		Rect lineBounds = new Rect ();
		lineBounds.width = 0;
		lineBounds.height = 0;
		lineBounds.x = x1;
		lineBounds.y = y1;
		
		lineBounds = UnionRect (lineBounds, x2, y2);
		
		lineBounds = ExpandRect (lineBounds, tolerance, tolerance);
		if (!lineBounds.Contains (new Vector2 (px, py))) {
			return false;
		}

		/*
           * If this is horizontal, vertical line or dot then the distance between
           * specified point and segment is not more then tolerance (due to the
           * lineBounds check above)
           */
		if (x1 == x2 || y1 == y2) {
			return true;
		}

		/*
           * Calculating square distance from specified point to this segment
           * using formula for Dot product of two vectors.
           */
		float v1x = x2 - x1;
		float v1y = y2 - y1;
		float v2x = px - x1;
		float v2y = py - y1;
		float numerator = v2x * v1y - v1x * v2y;
		float denominator = v1x * v1x + v1y * v1y;
		float squareDistance = numerator * numerator / denominator;
		return squareDistance <= tolerance * tolerance;
	}


}