ThomagicRenderer/Runtime/CellLayout.cs

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

namespace Assets.ThoMagic.Renderer
{
    public class CellLayout
    {
        public Vector3 Origin;
        private readonly int _cellsX;
        private readonly int _cellsZ;
        private readonly float _cellSizeX;
        private readonly float _cellSizeZ;
        private readonly Cell[] _cells;
        private readonly Dictionary<int, Plane[]> _cameraPlanes = new Dictionary<int, Plane[]>();
        private const int _planeCount = 6;
        private int _cachedFrameId;
        private Camera _cachedCamera;
        private Plane[] _planes = new Plane[6];
        private Double3[] _absNormals = new Double3[6];
        private Double3[] _planeNormal = new Double3[6];
        private double[] _planeDistance = new double[6];

        public CellLayout(float cellSizeX, float cellSizeZ, Bounds worldBounds)
        {
            Origin = worldBounds.min;
            _cellSizeX = cellSizeX;
            _cellSizeZ = cellSizeZ;
            _cellsX = Mathf.CeilToInt(worldBounds.size.x / _cellSizeX);
            _cellsZ = Mathf.CeilToInt(worldBounds.size.z / _cellSizeZ);
            _cells = new Cell[_cellsX * _cellsZ];
            float num1 = _cellSizeX * 0.5f;
            float num2 = _cellSizeZ * 0.5f;
            for (int index1 = 0; index1 < _cellsZ; ++index1)
            {
                for (int index2 = 0; index2 < _cellsX; ++index2)
                {
                    int index3 = index1 * _cellsX + index2;
                    float num3 = (float)index2 * _cellSizeX + num1;
                    float num4 = (float)index1 * _cellSizeZ + num2;
                    _cells[index3].HeightMin = double.MaxValue;
                    _cells[index3].HeightMax = double.MinValue;
                    _cells[index3].Center = new Double3((double)num3, 0.0, (double)num4);
                    _cells[index3].Extends = new Double3((double)num1, double.NaN, (double)num2);
                }
            }
        }

        public Cell[] GetCells() => _cells;

        public int GetCellCount() => _cells.Length;

        public void OverwriteCellHeightBounds()
        {
            int length = _cells.Length;
            for (int index = 0; index < length; ++index)
                _cells[index].HeightOverwrite = true;
        }

        public void SetCellHeightBounds(int cellIndex, double min, double max)
        {
            ref Cell local = ref _cells[cellIndex];
            if (local.HeightOverwrite)
            {
                local.HeightOverwrite = false;
                local.HeightMax = max;
                local.HeightMin = min;
            }
            else
            {
                local.HeightMax = Math.Max(local.HeightMax, max);
                local.HeightMin = Math.Min(local.HeightMin, min);
            }
            local.Center = new Double3(local.Center.x, (local.HeightMax + local.HeightMin) * 0.5, local.Center.z);
            local.Extends = new Double3(local.Extends.x, (local.HeightMax + local.HeightMin) * 0.5, local.Extends.z);
        }

        public void Update(Camera camera, int frameId, bool frustumCulling)
        {
            if (camera == _cachedCamera && frameId == _cachedFrameId)
                return;
            _cachedCamera = camera;
            _cachedFrameId = frameId;
            Plane[] planes;
            if (!_cameraPlanes.TryGetValue(((object)camera).GetHashCode(), out planes))
                _cameraPlanes[((object)camera).GetHashCode()] = planes = new Plane[6];
            GeometryUtility.CalculateFrustumPlanes(camera, planes);
            SetPlanes(planes);
            double x1 = camera.transform.position.x;
            double z1 = camera.transform.position.z;
            Double3 absNormal1 = _absNormals[0];
            Double3 absNormal2 = _absNormals[1];
            Double3 absNormal3 = _absNormals[2];
            Double3 absNormal4 = _absNormals[3];
            Double3 absNormal5 = _absNormals[4];
            Double3 absNormal6 = _absNormals[5];
            Double3 double3_1 = _planeNormal[0];
            Double3 double3_2 = _planeNormal[1];
            Double3 double3_3 = _planeNormal[2];
            Double3 double3_4 = _planeNormal[3];
            Double3 double3_5 = _planeNormal[4];
            Double3 double3_6 = _planeNormal[5];
            double num1 = _planeDistance[0];
            double num2 = _planeDistance[1];
            double num3 = _planeDistance[2];
            double num4 = _planeDistance[3];
            double num5 = _planeDistance[4];
            double num6 = _planeDistance[5];
            double x2 = (double)Origin.x;
            double y = (double)Origin.y;
            double z2 = (double)Origin.z;
            int length = _cells.Length;
            for (int index = 0; index < length; ++index)
            {
                ref Cell local = ref _cells[index];
                double num7 = local.Center.x + x2;
                double num8 = local.Center.y + y;
                double num9 = local.Center.z + z2;
                Double3 extends = local.Extends;
                local.DistanceX = Math.Abs(x1 - num7);
                local.DistanceZ = Math.Abs(z1 - num9);
                if (frustumCulling && !double.IsNaN(extends.y))
                {
                    bool flag = extends.x * absNormal1.x + extends.y * absNormal1.y + extends.z * absNormal1.z + (double3_1.x * num7 + double3_1.y * num8 + double3_1.z * num9) < -num1 || extends.x * absNormal2.x + extends.y * absNormal2.y + extends.z * absNormal2.z + (double3_2.x * num7 + double3_2.y * num8 + double3_2.z * num9) < -num2 || extends.x * absNormal3.x + extends.y * absNormal3.y + extends.z * absNormal3.z + (double3_3.x * num7 + double3_3.y * num8 + double3_3.z * num9) < -num3 || extends.x * absNormal4.x + extends.y * absNormal4.y + extends.z * absNormal4.z + (double3_4.x * num7 + double3_4.y * num8 + double3_4.z * num9) < -num4 || extends.x * absNormal5.x + extends.y * absNormal5.y + extends.z * absNormal5.z + (double3_5.x * num7 + double3_5.y * num8 + double3_5.z * num9) < -num5 || extends.x * absNormal6.x + extends.y * absNormal6.y + extends.z * absNormal6.z + (double3_6.x * num7 + double3_6.y * num8 + double3_6.z * num9) < -num6;
                    local.InFrustum = !flag;
                }
                else
                    local.InFrustum = true;
            }
        }

        private void SetPlanes(Plane[] planes)
        {
            _planes = planes;
            for (int index = 0; index < 6; ++index)
            {
                Plane plane = _planes[index];
                Vector3 vector = plane.normal;
                Double3 double3 = new Double3(in vector);
                _absNormals[index] = new Double3(Math.Abs(double3.x), Math.Abs(double3.y), Math.Abs(double3.z));
                _planeNormal[index] = double3;
                _planeDistance[index] = plane.distance;
            }
        }

        public struct Cell
        {
            public double DistanceX;
            public double DistanceZ;
            public bool InFrustum;
            public Double3 Center;
            public Double3 Extends;
            public double HeightMin;
            public double HeightMax;
            public bool HeightOverwrite;
        }

        public readonly struct Double3
        {
            public readonly double x;
            public readonly double y;
            public readonly double z;

            public Double3(in Vector3 vector)
            {
                x = (double)vector.x;
                y = (double)vector.y;
                z = (double)vector.z;
            }

            public Double3(double x, double y, double z)
            {
                this.x = x;
                this.y = y;
                this.z = z;
            }
        }
    }
}