ScenePartition/Editor/ScenePartitionSceneViewEditor.cs

using UnityEditor;
using UnityEngine;

namespace VertexColor.ScenePartition.Editor
{
    [InitializeOnLoad]
    public class ScenePartitionSceneViewEditor : UnityEditor.Editor
    {
        public static int cellSize = 100;

        private static ScenePartitionSO scenePartitionSO = null;

        static ScenePartitionSceneViewEditor()
        {
            SceneView.duringSceneGui += HandleDuringSceneGui;
        }

        private static void HandleDuringSceneGui(SceneView sceneView)
        {
            if (Event.current.modifiers != EventModifiers.Control) return;
            if (!ScenePartitionUtils.TryGetScenePartitionSOForActiveScene(out scenePartitionSO)) return;

            Vector3 gridPosition = CalculateGridPosition(Event.current.mousePosition);
            int gridId = SceneGrid.CalculateGridPosition(gridPosition, cellSize);

            {   // Draw Cells.
                foreach (int id in scenePartitionSO.Data.SceneGrid.Grid.Keys)
                {
                    (int x, int y) = SceneGrid.IntToIntPair(id);

                    Vector3 cellOrign = new Vector3(x * cellSize, 0, y * cellSize);
                    Vector3[] lines = new Vector3[] {
                        new Vector3(0, 0, 0) + cellOrign, new Vector3(0, 0, cellSize) + cellOrign,                  // Left Bottom -> Left Top
                        new Vector3(cellSize, 0, 0) + cellOrign, new Vector3(cellSize, 0, cellSize) + cellOrign,    // Right Bottom -> Right Top
                        new Vector3(0, 0, 0) + cellOrign, new Vector3(cellSize, 0, 0) + cellOrign,                  // Left Bottom -> Right Bottom
                        new Vector3(0, 0, cellSize) + cellOrign, new Vector3(cellSize, 0, cellSize) + cellOrign,    // Left Top -> Right Top
                    };

                    Handles.DrawLines(lines);
                }
            }

            if (!scenePartitionSO.Data.SceneGrid.Grid.ContainsKey(gridId)) return;

            {   // Draw Selection.
                int x = Mathf.FloorToInt(gridPosition.x / cellSize);
                int z = Mathf.FloorToInt(gridPosition.z / cellSize);

                Vector3 cellOrign = new Vector3(x * cellSize, 0, z * cellSize);
                Vector3[] lines = new Vector3[] {
                    new Vector3(0, 0, 0) + cellOrign, new Vector3(0, 0, cellSize) + cellOrign,                  // Left Bottom -> Left Top
                    new Vector3(cellSize, 0, 0) + cellOrign, new Vector3(cellSize, 0, cellSize) + cellOrign,    // Right Bottom -> Right Top
                    new Vector3(0, 0, 0) + cellOrign, new Vector3(cellSize, 0, 0) + cellOrign,                  // Left Bottom -> Right Bottom
                    new Vector3(0, 0, cellSize) + cellOrign, new Vector3(cellSize, 0, cellSize) + cellOrign,    // Left Top -> Right Top
                };

                Color c = Handles.color;
                Handles.color = Color.yellow;
                Handles.DrawLines(lines);
                Handles.color = c;
            }

            // Context menu to load.
            if (Event.current.button == 1 && Event.current.type == EventType.MouseDown)
            {
                GenericMenu menu = new GenericMenu();

                menu.AddItem(new GUIContent($"Load {gridId}"), false, Load, gridId);
                menu.ShowAsContext();

                Event.current.Use();
            }

            SceneView.RepaintAll();
        }

        private static Vector3 CalculateGridPosition(Vector2 mousePosition)
        {
            if (Event.current == null) return Vector3.zero;

            Ray ray = HandleUtility.GUIPointToWorldRay(mousePosition);
            Plane plane = new Plane(Vector3.up, Vector3.zero); // Horizontal plane at y = 0

            if (!plane.Raycast(ray, out float distance)) return Vector3.zero;

            Vector3 intersectionPoint = ray.GetPoint(distance);
            return intersectionPoint;
        }

        private static void Load(object gridId)
        {
            if (scenePartitionSO == null) return;
            if (gridId == null) return;
            if (gridId is not int cellId) return;

            scenePartitionSO.LoadCell(cellId);
        }
    }
}