Building an Atlas Slicer

alright, following difficulty with converting slices sprites to textures, I decided to build an editor window to do this.
So far, I have a way to load up a texture, display divider lines, and set how many textures there are in the atlas.

I've hit a bit of a snag. When I set the texture count greater than the x axis dimensions, the display just continues adding tiles to the right, and I can't work out how to get it to drop down, so I can get the other rows.

This is kind of difficult to explain so I'm just going to attach my script below.

I believe this bug is on line 246, but I can't work out for the life of me how to fix it. I've tried many combinations of calculations for the Rect locations and can't work it out.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEditor;
5. using System;
6.  
7. public class ArcaneAtlasSlicer : EditorWindow
8. {
9.     private Vector2 _scrollPosition;
10.     private Vector2 _scrollPosition2;
11.  
12.     bool debugSect;
13.     bool texSect;
14.  
15.     private List<Texture2D> slicedTextures;
16.  
17.     Color headerColor = new Color(0.65f, 0.65f, 0.65f, 1);
18.  
19.     GUIStyle btnSmall;
20.  
21.     Texture2D activeTexture;
22.     Vector2 atlasDimensions = new Vector2(1f, 1f);
23.     int atlasTextureCnt;
24.     Color debugLineColor = Color.white;
25.     bool debugLines = true;
26.     Color debugTexColor = new Color(1f, 0.5f, 0.5f, 1.0f);
27.     bool debugTexs = true;
28.  
29.     bool example;
30.  
31.     [MenuItem("Arcane Engine/Atlas Slicer", false, 102)]
32.     public static void Init()
33.     {
34.         EditorWindow arcaneSlicer = GetWindow(typeof(ArcaneAtlasSlicer), false, "Arc Slicer");
35.         arcaneSlicer.Show();
36.     }
37.  
38.     void OnInspectorUpdate()
39.     {
40.         Repaint();
41.     }
42.  
43.     void OnGUI()
44.     {
45.         #region setup
46.         Rect texRect = new Rect((position.width / 4) / 2, (position.height - ((position.width / 4) * 2)) / 2, (position.width / 4) * 2, (position.width / 4) * 2);
47.  
48.         btnSmall = new GUIStyle("ShurikenModuleTitle");
49.         btnSmall.fixedHeight = 20;
50.         btnSmall.fixedWidth = 20;
51.         btnSmall.padding = new RectOffset(-10, 0, 0, 0);
52.         btnSmall.margin = new RectOffset(0, 4, 2, 0);
53.         #endregion
54.  
55.         Vector2 tmpDimensions = new Vector2((float)Math.Truncate(atlasDimensions.x), (float)Math.Truncate(atlasDimensions.y));
56.         if (tmpDimensions.x < 1)
57.         {
58.             tmpDimensions.x = 1;
59.         }
60.         if (tmpDimensions.y < 1)
61.         {
62.             tmpDimensions.y = 1;
63.         }
64.  
65.         atlasDimensions = tmpDimensions;
66.  
67.         if (atlasTextureCnt < 1)
68.         {
69.             atlasTextureCnt = 1;
70.         }
71.         if (atlasTextureCnt > tmpDimensions.x * tmpDimensions.y)
72.         {
73.             atlasTextureCnt = (int)(tmpDimensions.x * tmpDimensions.y);
74.         }
75.  
76.         if (!EditorGUIUtility.isProSkin)
77.         {
78.             headerColor = new Color(165 / 255f, 165 / 255f, 165 / 255f, 1);
79.             //backgroundColor = new Color(193 / 255f, 193 / 255f, 193 / 255f, 1);
80.         }
81.         else
82.         {
83.             headerColor = new Color(41 / 255f, 41 / 255f, 41 / 255f, 1);
84.             //backgroundColor = new Color(56 / 255f, 56 / 255f, 56 / 255f, 1);
85.         }
86.  
87.         GUIStyle labelCentred = new GUIStyle("Label");
88.         labelCentred.alignment = TextAnchor.MiddleCenter;
89.  
90.         GUIStyle bigLabelCentre = new GUIStyle("Label");
91.         bigLabelCentre.alignment = TextAnchor.MiddleCenter;
92.         bigLabelCentre.fontSize = 20;
93.         bigLabelCentre.stretchHeight = true;
94.         bigLabelCentre.stretchWidth = true;
95.  
96.         Texture2D backg = new Texture2D(1, 1, TextureFormat.RGBA32, false);
97.         backg.SetPixel(0, 0, new Color(0.30f, 0.30f, 0.30f, 1.0f));
98.         backg.Apply();
99.  
100.         Texture2D debugBg = new Texture2D(1, 1, TextureFormat.RGBA32, false);
101.         debugBg.SetPixel(0, 0, debugTexColor);
102.         debugBg.Apply();
103.  
104.         EditorGUILayout.BeginHorizontal(); //Begin Whole Window
105.  
106.         #region Sidebar
107.         EditorGUILayout.BeginVertical(GUILayout.Width(position.width / 4)); //Begin Sidebar
108.         _scrollPosition2 = GUILayout.BeginScrollView(_scrollPosition2);
109.  
110.         GUI.DrawTexture(new Rect(0, 0, position.width / 4, position.height), backg, ScaleMode.StretchToFill);
111.  
112.         EditorGUILayout.BeginHorizontal(EditorStyles.toolbar, GUILayout.ExpandWidth(true));
113.         {
114.             GUILayout.Label("Menu", labelCentred);
115.         }
116.         EditorGUILayout.EndHorizontal();
117.  
118.         //Texture
119.         GUILayout.Label("Atlas", EditorStyles.boldLabel);
120.         activeTexture = (Texture2D)EditorGUILayout.ObjectField("Atlas Texture", activeTexture, typeof(Texture2D), true);
121.         using (new EditorGUILayout.HorizontalScope())
122.         {
123.             GUI.backgroundColor = Color.red;
124.             if (GUILayout.Button("Clear Atlas Texture"))
125.             {
126.                 activeTexture = null;
127.             }
128.             GUI.backgroundColor = Color.white;
129.         }
130.  
131.         EditorGUILayout.Space();
132.  
133.         //Settings
134.         GUILayout.Label("Atlas Settings", EditorStyles.boldLabel);
135.         atlasDimensions = EditorGUILayout.Vector2Field("Atlas Dimensions", atlasDimensions);
136.  
137.         using (new EditorGUILayout.HorizontalScope())
138.         {
139.             GUILayout.Label("");
140.             if (GUILayout.Button(new GUIContent("+", "x + 1")))
141.             {
142.                 atlasDimensions.x++;
143.             }
144.             if (GUILayout.Button(new GUIContent("-", "x - 1")))
145.             {
146.                 atlasDimensions.x--;
147.             }
148.             GUILayout.Label("");
149.             if (GUILayout.Button(new GUIContent("+", "y + 1")))
150.             {
151.                 atlasDimensions.y++;
152.             }
153.             if (GUILayout.Button(new GUIContent("-", "y - 1")))
154.             {
155.                 atlasDimensions.y--;
156.             }
157.         }
158.         EditorGUILayout.HelpBox("The dimensions the atlas will be divided by. 4 images in a 2x2 grid would be x2 y2 (use whole numbers).", MessageType.None);
159.         atlasTextureCnt = EditorGUILayout.IntField("Atlas Texture Count", atlasTextureCnt);
160.  
161.         using (new EditorGUILayout.HorizontalScope())
162.         {
163.             GUILayout.Label("");
164.             if (GUILayout.Button(new GUIContent("+", "Texture count + 1")))
165.             {
166.                 atlasTextureCnt++;
167.             }
168.             if (GUILayout.Button(new GUIContent("-", "Texture count - 1")))
169.             {
170.                 atlasTextureCnt--;
171.             }
172.         }
173.         EditorGUILayout.HelpBox("The total number of individual textures in the atlas (allows blank spaces to be ignored).", MessageType.None);
174.  
175.         EditorGUILayout.Space();
176.  
177.         debugSect = Foldout("Debug", debugSect);
178.         if (debugSect)
179.         {
180.             debugLines = EditorGUILayout.Toggle("Debug Lines", debugLines);
181.             debugLineColor = EditorGUILayout.ColorField("Line Color", debugLineColor);
182.             debugTexs = EditorGUILayout.Toggle("Debug Textures", debugTexs);
183.             debugTexColor = EditorGUILayout.ColorField("Texture Color", debugTexColor);
184.         }
185.  
186.         //Build sliced Images
187.         texSect = Foldout("Textures", texSect);
188.         if(texSect)
189.         {
190.             if(slicedTextures.Count <= 0)
191.             {
192.                 GUILayout.Label("No sliced textures available.");
193.             }
194.             for(int i = 0; i < atlasTextureCnt; i++)
195.             {
196.                 slicedTextures[i] = (Texture2D)EditorGUILayout.ObjectField(i.ToString() + " Sliced", slicedTextures[i], typeof(Texture2D), true);
197.                 slicedTextures[i] = activeTexture;
198.             }
199.             if(slicedTextures.Count > 0)
200.             {
201.                 GUI.backgroundColor = Color.green;
202.                 if(GUILayout.Button("Export Textures"))
203.                 {
204.  
205.                 }
206.                 GUI.backgroundColor = Color.white;
207.             }
208.         }
209.  
210.         GUILayout.EndScrollView();
211.         EditorGUILayout.EndVertical(); //End Sidebar
212.         #endregion
213.  
214.         #region Main Window
215.         EditorGUILayout.BeginVertical(); //Begin Main Window
216.         _scrollPosition = GUILayout.BeginScrollView(_scrollPosition);
217.  
218.         EditorGUILayout.BeginHorizontal(EditorStyles.toolbar, GUILayout.ExpandWidth(true));
219.         {
220.             GUILayout.Label("Arcane Engine Atlas Slicer", labelCentred);
221.         }
222.         EditorGUILayout.EndHorizontal();
223.  
224.         if (activeTexture == null)
225.         {
226.             //Display Error
227.             GUILayout.Label("No Atlas Selected", bigLabelCentre);
228.         }
229.         else
230.         {
231.             //Display Texture
232.             GUI.DrawTexture(texRect, activeTexture);
233.  
234.             //Draw Bounding Lines
235.             Handles.BeginGUI();
236.  
237.             //Generate Debugs
238.             if (debugTexs)
239.             {
240.                 for (int i = 0; i < atlasTextureCnt; i++)
241.                 {
242.                     GUIStyle tmpTex = new GUIStyle("Label");
243.                     tmpTex.fontSize = 15;
244.                     tmpTex.contentOffset = new Vector2(texRect.xMin, texRect.yMin + texRect.height / atlasDimensions.y * i);
245.  
246.                     GUI.DrawTexture(new Rect(texRect.x + texRect.width / atlasDimensions.x * i, texRect.y, texRect.width / atlasDimensions.x, texRect.height / atlasDimensions.y), debugBg, ScaleMode.StretchToFill);
247.                 }
248.             }
249.  
250.             Handles.color = debugLineColor;
251.             Handles.DrawLine(new Vector3(texRect.xMin - 20, texRect.yMin), new Vector3(texRect.xMax + 20, texRect.yMin));   //Top Horizontal
252.             Handles.DrawLine(new Vector3(texRect.xMax, texRect.yMin - 20), new Vector3(texRect.xMax, texRect.yMax + 20));   //Bottom Horizontal
253.             Handles.DrawLine(new Vector3(texRect.xMin, texRect.yMin - 20), new Vector3(texRect.xMin, texRect.yMax + 20));   //Left Vertical
254.             Handles.DrawLine(new Vector3(texRect.xMin - 20, texRect.yMax), new Vector3(texRect.xMax + 20, texRect.yMax));   //Right Vertical
255.  
256.             if (debugLines)
257.             {
258.                 //Draw Vertical Dimension Handles
259.                 for (int i = 1; i < atlasDimensions.x; i++)
260.                 {
261.                     Handles.DrawLine(new Vector3(texRect.xMin + texRect.width / atlasDimensions.x * i, texRect.yMin), new Vector3(texRect.xMin + texRect.width / atlasDimensions.x * i, texRect.yMax));
262.                 }
263.                 //Draw Horizontal Dimension Handles
264.                 for (int i = 1; i < atlasDimensions.y; i++)
265.                 {
266.                     Handles.DrawLine(new Vector3(texRect.xMin, texRect.yMin + texRect.height / atlasDimensions.y * i), new Vector3(texRect.xMax, texRect.yMin + texRect.height / atlasDimensions.y * i));
267.                 }
268.             }
269.  
270.             Handles.EndGUI();
271.         }
272.  
273.         GUILayout.EndScrollView();
274.         EditorGUILayout.EndVertical(); //End Main Window
275.         #endregion
276.         EditorGUILayout.EndHorizontal(); //End Whole Window
277.     }
278.  
279.     public static bool Foldout(string title, bool display)
280.     {
281.         var style = new GUIStyle("ShurikenModuleTitle");
282.         style.font = new GUIStyle(EditorStyles.label).font;
283.         style.border = new RectOffset(15, 7, 4, 4);
284.         style.fixedHeight = 22;
285.         style.contentOffset = new Vector2(20f, -2f);
286.  
287.         var rect = GUILayoutUtility.GetRect(16f, 22f, style);
288.         GUI.Box(rect, title, style);
289.  
290.         var e = Event.current;
291.  
292.         var toggleRect = new Rect(rect.x + 4f, rect.y + 2f, 13f, 13f);
293.         if (e.type == EventType.Repaint)
294.         {
295.             EditorStyles.foldout.Draw(toggleRect, false, false, display, false);
296.         }
297.  
298.         if (e.type == EventType.MouseDown && rect.Contains(e.mousePosition))
299.         {
300.             display = !display;
301.             e.Use();
302.         }
303.  
304.         return display;
305.     }
306. }