Add custom grid snapping value for translation

#1823

Source/Editor/Viewport/EditorGizmoViewport.cs

@@ -4,6 +4,7 @@ using System;
 using System.Collections.Generic;
 using FlaxEditor.Gizmo;
 using FlaxEditor.GUI.ContextMenu;
+using FlaxEditor.GUI.Input;
 using FlaxEditor.SceneGraph;
 using FlaxEditor.Viewport.Cameras;
 using FlaxEditor.Viewport.Widgets;
@@ -298,9 +299,33 @@ namespace FlaxEditor.Viewport
             }
             var buttonBB = translateSnappingCM.AddButton("Bounding Box").LinkTooltip("Snaps the selection based on it's bounding volume");
             buttonBB.Tag = -1.0f;
-            translateSnappingCM.ButtonClicked += button =>
+            var buttonCustom = translateSnappingCM.AddButton("Custom");
+            buttonCustom.LinkTooltip("Custom grid size");
+            const float defaultCustomTranslateSnappingValue = 250.0f;
+            float customTranslateSnappingValue = transformGizmo.TranslationSnapValue;
+            if (customTranslateSnappingValue < 0.0f)
+                customTranslateSnappingValue = defaultCustomTranslateSnappingValue;
+            foreach (var v in TranslateSnapValues)
             {
-                var v = (float)button.Tag;
+                if (Mathf.Abs(transformGizmo.TranslationSnapValue - v) < 0.001f)
+                {
+                    customTranslateSnappingValue = defaultCustomTranslateSnappingValue;
+                    break;
+                }
+            }
+            buttonCustom.Tag = customTranslateSnappingValue;
+            var customValue = new FloatValueBox(customTranslateSnappingValue, Style.Current.FontMedium.MeasureText(buttonCustom.Text).X + 5, 2, 70.0f, 0.001f, float.MaxValue, 0.1f)
+            {
+                Parent = buttonCustom
+            };
+            customValue.ValueChanged += () =>
+            {
+                buttonCustom.Tag = customValue.Value;
+                buttonCustom.Click();
+            };
+            translateSnappingCM.ButtonClicked += b =>
+            {
+                var v = (float)b.Tag;
                 transformGizmo.TranslationSnapValue = v;
                 if (v < 0.0f)
                     translateSnapping.Text = "Bounding Box";