VectorTile.cs

using Mapbox.Vector.Tile;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using UnityEditor;
using UnityEngine;
using UnityEngine.Networking;
using static Wander.Easing;

namespace Wander
{
    // Always multiple of 3. Each 3 form a triangle.
    public class TriangulatedPolygon
    {
        public List<Vector2> vertices;  
        public List<Vector2> mins;
        public List<Vector2> maxs;
        public List<float>   denoms;

        public void OptimizeForIsPointInTriangle()
        {
            if ( vertices == null ) return; // Non poly layers have this.

            mins   = new List<Vector2>( vertices.Count / 3 );
            maxs   = new List<Vector2>( vertices.Count / 3 );
            denoms = new List<float>( vertices.Count / 3 );

            for ( int i = 0; i < vertices.Count; i += 3 )
            {
                float minx = float.MaxValue;
                float miny = float.MaxValue;    
                if (vertices[i+0].x < minx) minx = vertices[i].x;
                if (vertices[i+0].y < miny) miny = vertices[i].y;
                if (vertices[i+1].x < minx) minx = vertices[i+1].x;
                if (vertices[i+1].y < miny) miny = vertices[i+1].y;
                if (vertices[i+2].x < minx) minx = vertices[i+2].x;
                if (vertices[i+2].y < miny) miny = vertices[i+2].y;
                mins.Add( new Vector2( minx, miny ) );

                float maxx = float.MinValue;
                float maxy = float.MinValue;
                if (vertices[i+0].x > maxx) maxx = vertices[i].x;
                if (vertices[i+0].y > maxy) maxy = vertices[i].y;
                if (vertices[i+1].x > maxx) maxx = vertices[i+1].x;
                if (vertices[i+1].y > maxy) maxy = vertices[i+1].y;
                if (vertices[i+2].x > maxx) maxx = vertices[i+2].x;
                if (vertices[i+2].y > maxy) maxy = vertices[i+2].y;
                maxs.Add( new Vector2( maxx, maxy ) );

                // float denominator = ((vertex2.y - vertex3.y) * (vertex1.x - vertex3.x) + (vertex3.x - vertex2.x) * (vertex1.y - vertex3.y));
                float denominator = ((vertices[i+1].y - vertices[i+2].y) * (vertices[i].x - vertices[i+2].x) + (vertices[i+2].x - vertices[i+1].x) * (vertices[i].y - vertices[i+2].y));
                denominator = 1.0f / denominator;
                denoms.Add( denominator );
            }
        }
    }

    public class VectorTile
    {
        public bool DownloadStarted => started;
        public bool Valid => valid;
        public bool Finished => finished;
        public bool Triangulated => triangulated;

        private bool started;
        private bool valid;
        private bool finished;
        private bool triangulated;
        private bool layersIdentified;
        private Task parseTileTask;
        private List<VectorTileLayer> layers;
        private List<List<TriangulatedPolygon>> polygonLayers;

        internal UnityWebRequest request;

        public void StartDownload()
        {
            Debug.Assert(!started);
            request.SendWebRequest();
            started = true;
        }

        public bool IsFinished()
        {
            if (finished)
                return true;

            if (!request.isDone)
                return false;

            if (request.result == UnityWebRequest.Result.Success)
            {
                if (parseTileTask == null)
                {
                    var data = request.downloadHandler.data; // call on mainthread.
                    parseTileTask = Task.Run( () =>
                    {
                        var stream = new MemoryStream( data );
                        layers = VectorTileParser.Parse( stream );
                    } );
                }
                else if (parseTileTask.IsCompleted)
                {
                    valid = parseTileTask.IsCompletedSuccessfully;
                    finished = true;
                    parseTileTask = null;
                }
            }

            return finished;
        }

        static bool IsTriangleCCW( Vector2 vertex1, Vector2 vertex2, Vector2 vertex3 )
        {
            float signedArea = (vertex2.x - vertex1.x) * (vertex3.y - vertex1.y) - (vertex3.x - vertex1.x) * (vertex2.y - vertex1.y);
            return signedArea > 0;
        }

        // Number of failed polys to triangulate are returned.
        public int Triangulate()
        {
            if (triangulated )
                return 0;
            int numFailedPolys = 0;
            polygonLayers = new List<List<TriangulatedPolygon>>();
            List<double> vertices = new List<double>();
            List<int> holeIndices = new List<int>();
            for ( int i =0; i < layers.Count; i++ )
            {
                var features = layers[i].VectorTileFeatures;
                var polygons = new List<TriangulatedPolygon>();
                for (int j = 0; j< features.Count; j++)
                {
                    polygons.Add( new TriangulatedPolygon() ); // Add empty to ensure list(layer) of lists(features) match.
                    if (features[j].GeometryType != Tile.GeomType.Polygon)
                    {
                        continue;
                    }
                    vertices.Clear();
                    holeIndices.Clear();
                    var rings = features[j].Geometry;
                    for (int k = 0;k < rings.Count;k++)
                    {
                        if (k != 0) // if is not first ring, this is a hole
                        {
                            holeIndices.Add( vertices.Count / 2 );
                        }
                        var ring = rings[k];
                        for (int q = 0;q < ring.Count;q++)
                        {
                            vertices.Add( ring[q].X );
                            vertices.Add( ring[q].Y );
                        }
                    }
                    try
                    {
                        var indices = EarcutNet.Earcut.Tessellate( vertices, holeIndices );
                        TriangulatedPolygon poly = new TriangulatedPolygon();
                        poly.vertices = new List<Vector2>( indices.Count );
                        for (int k = 0;k < indices.Count; k++)
                        {
                            double x = vertices[indices[k]*2];
                            double y = vertices[indices[k]*2+1];
                            poly.vertices.Add( new Vector2( (float)x, (float)y ) );
                        }
                        //for ( int k = 0; k < indices.Count; k += 3)
                        //{
                        //    if ( !IsTriangleCCW( poly.vertices[k], poly.vertices[k+1], poly.vertices[k+2] ))
                        //    {
                        //        var t = poly.vertices[k];
                        //        poly.vertices[k] = poly.vertices[k+2];
                        //        poly.vertices[k+2] = t;
                        //    }
                        //}
                        polygons[polygons.Count-1] = poly;
                        Debug.Assert( poly.vertices.Count % 3 == 0 );
                    }
                    catch (Exception)
                    {
                        numFailedPolys++;
                    }
                }
                polygonLayers.Add( polygons );
            }
            triangulated = true;
            return numFailedPolys;
        }

        public void OptimizeForPointIsInsideTriangle()
        {
            for (int i = 0;i < polygonLayers.Count;i++)
                for (int j = 0;j < polygonLayers[i].Count;j++)
                    polygonLayers[i][j].OptimizeForIsPointInTriangle();
        }

        // Identify feature by specifying a (unique) index based on some criteria. This can very per
        // vector tile provider. 
        public void IdentifyLayers( Func<VectorTileLayer, List<KeyValuePair<string, object>>, int> selectionCallback,
                                    Func<VectorTileLayer, List<KeyValuePair<string, object>>, int> relativeHeightCallback )
        {
            for (int l = 0;l < layers.Count;l++)
            {
                var layer  = layers[l];
                for (int f = 0;f < layer.VectorTileFeatures.Count;f++)
                {
                    var feature = layer.VectorTileFeatures[f];
                    feature.SelectedLayerIdx = 254;

                    int uniqueId = selectionCallback( layer, feature.Attributes );
                    if (uniqueId > -1)
                    {
                        feature.SelectedLayerIdx = uniqueId;
                    }
                    uniqueId = relativeHeightCallback( layer, feature.Attributes );
                    feature.RelativeHeight = uniqueId;
                }
            }
            layersIdentified = true;
        }

        // Calls callback(x, y, channel) for each raster position (256 channels) where each value represents a single channel.
        // If no polygon was hit, 255 is called.
        // If polygon was hit, but no feature was matched, 254 is called.
        // Returns a list of failed to match pixels. This can be due to geometry not exactly matching or a layer not being found.
        // Also out puts a remap of layer indices. For instance for a specific tile, only layerIdx 1, 6 and 3 are used.
        // Then this a remapping of 1->0, 6->1, 3->2. So that in the shader only 3 textures are needed starting from 0, 1.. etc.
        public byte[] RenderToTextureSingle(
            int resolution,
            out Dictionary<byte, byte> remappedLayerIndices,     
            out List<Vector3Int> failedPixels,
            bool? cancelToken )
        {
            Debug.Assert( triangulated, "First call Triangulate." );
            Debug.Assert( layersIdentified, "Identify layers first." );
            Debug.Assert( resolution > 1, "Must be at least 2." );

            byte [] texture = new byte[resolution*resolution];
            failedPixels = new List<Vector3Int>();
            remappedLayerIndices = new Dictionary<byte, byte>();
            float oneOverRes = 1.0f / resolution;

            int cachedTriIdx  = 0;
            int cachedLyrIdx  = 0;
            int cachedFtrIdx  = 0;

            // For each pixel.
            for (int y = 0;y < resolution ;y++)
            {
                for (int x = 0;x < resolution && !cancelToken.Value ;x++)
                {
                    bool hit  = false;

                    // For each layer, check triangle intersections.
                    for (int l = 0;l < layers.Count && !cancelToken.Value;l++)
                    {
                        var lIdx  = (l+cachedLyrIdx) % layers.Count; // Try last layer/feature/triangle first.
                        var layer = layers[lIdx];
                        float fx  = layer.Extent * oneOverRes;
                        Vector2 p = new Vector2(fx*x+0.5f, fx*y+0.5f);

                        for (int f = 0;f < layer.VectorTileFeatures.Count;f++)
                        {
                            var ftrIdx  = (f + cachedFtrIdx) % layer.VectorTileFeatures.Count;
                            var feature = layer.VectorTileFeatures[ftrIdx];

                            if (feature.GeometryType != Tile.GeomType.Polygon)
                                continue;

                            var polygons = polygonLayers[lIdx][ftrIdx];
                            if (polygons.vertices.Count == 0)
                                continue;

                            if (feature.SelectedLayerIdx == 254)
                                continue;

                            if (feature.RelativeHeight > 0)
                                continue;

                            var poly     = polygonLayers[lIdx][ftrIdx];
                            var mins     = poly.mins;
                            var maxs     = poly.maxs;
                            var denoms   = poly.denoms;
                            var vertices = poly.vertices;
                            var triCount = vertices.Count/3;
                            for (int t = 0; t < triCount;t++)
                            {
                                int triIdx = (t+cachedTriIdx) % triCount;
                                if (p.x < mins[triIdx].x || p.x > maxs[triIdx].x) continue;
                                if (p.y < mins[triIdx].y || p.y > maxs[triIdx].y) continue;
                                hit = GeomUtil.PointIsInsideTriangle2( p, vertices[triIdx*3], vertices[triIdx*3+1], vertices[triIdx*3+2], denoms[triIdx] );
                                if (hit)
                                {
                                    cachedTriIdx = triIdx;
                                    cachedLyrIdx = lIdx;
                                    cachedFtrIdx = ftrIdx;
                                    texture[(resolution - y -1)*resolution+x] = (byte)feature.SelectedLayerIdx;
                                    break;
                                }
                            }

                            if (hit) break;

                            cachedTriIdx += 1;
                            if(cachedTriIdx == triCount) cachedTriIdx = 0;
                        }

                        if (hit) break;

                        cachedFtrIdx = 0;
                    }

                    if (!hit)
                    {
                        cachedLyrIdx = 0;
                        texture[(resolution - y -1)*resolution+x] = 255;
                        failedPixels.Add( new Vector3Int( x, y, 255 ) );
                    }
                }
            }

            // Determine number of different layers. For instance, if only layer 3, 8, 14 and 15 are used, we select
            // a material that only uses 4 textures and put 3 -> Albedo_0 -> 8 to Albedo_1, etc. in the shader.
            byte cachedPixel = 255;
            int remappedIndexCounter = -1;
            byte remappedPixel = 255;
            int addr = 0;
            for (int y = 0;y < resolution && !cancelToken.Value;y++)
            {
                for (int x = 0;x < resolution;x++)
                {
                    byte pixel = texture[addr];
                    if (pixel < 254)
                    {
                        if (pixel != cachedPixel)
                        {
                            if (!remappedLayerIndices.TryGetValue( pixel, out remappedPixel ))
                            {
                                if (remappedIndexCounter < 253) // 254 is reserved for no layer match, 255 is ray hit with triangle.
                                {
                                    remappedIndexCounter++;
                                    remappedPixel = (byte)remappedIndexCounter;
                                    remappedLayerIndices.Add( pixel, remappedPixel );
                                }
                                else remappedPixel = 0;
                            }
                            cachedPixel = pixel;
                        }
                        texture[addr] = remappedPixel;
                    } // leave unfound or unhit pixels on their original value.
                    addr++;
                }
            }

            Debug.Assert(remappedIndexCounter <= 254, "Exceeded layer count." );
            return texture;
        }
    }

    public static class VectorTileLoader
    {
        public static VectorTile LoadFromUrl( string url, bool autoStart=true )
        {
            VectorTile tile = new VectorTile();
            tile.request = UnityWebRequest.Get( url );
            if (autoStart)
            {
                tile.StartDownload();
            }
            return tile;
        }
    }
}