import { vec3 } from 'gl-matrix';
import unique from '../../../common/arrayunique';
import urlWithParams from '../../../common/urlwithparams';
import { FetchDataTypeName } from '../../../common/fetchdatatype';
import { MappedData } from '../../../utils/mappeddata';
import War3Map from '../../../parsers/w3x/map';
import War3MapW3i from '../../../parsers/w3x/w3i/file';
import War3MapW3e from '../../../parsers/w3x/w3e/file';
import Corner from '../../../parsers/w3x/w3e/corner';
import War3MapDoo from '../../../parsers/w3x/doo/file';
import War3MapUnitsDoo from '../../../parsers/w3x/unitsdoo/file';
import ModelViewer from '../../viewer';
import ShaderProgram from '../../gl/program';
import Scene from '../../scene';
import Grid from '../../grid';
import { PathSolver } from '../../handlerresource';
import Texture from '../../texture';
import mdxHandler from '../mdx/handler';
import MdxModel from '../mdx/model';
import MdxModelInstance from '../mdx/modelinstance';
import getCliffVariation from './variations';
import TerrainModel from './terrainmodel';
import randomStandSequence from './standsequence';
import Unit from './unit';
import Doodad from './doodad';
import TerrainDoodad from './terraindoodad';
import groundVert from './shaders/ground.vert';
import groundFrag from './shaders/ground.frag';
import waterVert from './shaders/water.vert';
import waterFrag from './shaders/water.frag';
import cliffsVert from './shaders/cliffs.vert';
import cliffsFrag from './shaders/cliffs.frag';

const normalHeap1 = vec3.create();
const normalHeap2 = vec3.create();

export default class War3MapViewer extends ModelViewer {
  wc3PathSolver: PathSolver;
  solverParams: { tileset?: string, reforged?: boolean, hd?: boolean } = {};
  groundShader: ShaderProgram | null;
  waterShader: ShaderProgram | null;
  cliffShader: ShaderProgram | null;
  worldScene: Scene;
  waterIndex: number = 0;
  waterIncreasePerFrame: number = 0;
  waterHeightOffset: number = 0;
  waterTextures: Texture[] = [];
  maxDeepColor: Float32Array = new Float32Array(4);
  minDeepColor: Float32Array = new Float32Array(4);
  maxShallowColor: Float32Array = new Float32Array(4);
  minShallowColor: Float32Array = new Float32Array(4);
  anyReady: boolean = false;
  terrainCliffsAndWaterLoaded: boolean = false;
  terrainData: MappedData = new MappedData();
  cliffTypesData: MappedData = new MappedData();
  waterData: MappedData = new MappedData();
  terrainReady: boolean = false;
  cliffsReady: boolean = false;
  doodadsAndDestructiblesLoaded: boolean = false;
  doodadsData: MappedData = new MappedData();
  doodadMetaData: MappedData = new MappedData();
  destructableMetaData: MappedData = new MappedData();
  doodads: Doodad[] = [];
  terrainDoodads: any[] = [];
  doodadsReady: boolean = false;
  unitsAndItemsLoaded: boolean = false;
  unitsData: MappedData = new MappedData();
  unitMetaData: MappedData = new MappedData();
  units: Unit[] = [];
  unitsReady: boolean = false;
  tilesetTextures: Texture[] = [];
  cliffTextures: Texture[] = [];
  cliffModels: TerrainModel[] = [];
  mapMpq: War3Map | null = null;
  mapPathSolver: PathSolver | null = null;
  corners: Corner[][] = [];
  centerOffset: Float32Array = new Float32Array(2);
  mapSize: Int32Array = new Int32Array(2);
  tilesets: any[] = [];
  blightTextureIndex: number = -1;
  cliffTilesets: any[] = [];
  columns: number = 0;
  rows: number = 0;
  vertexBuffer: WebGLBuffer | null = null;
  faceBuffer: WebGLBuffer | null = null;
  instanceBuffer: WebGLBuffer | null = null;
  textureBuffer: WebGLBuffer | null = null;
  variationBuffer: WebGLBuffer | null = null;
  waterBuffer: WebGLBuffer | null = null;
  heightMap: WebGLTexture | null = null;
  waterHeightMap: WebGLTexture | null = null;
  cliffHeightMap: WebGLTexture | null = null;

  constructor(canvas: HTMLCanvasElement, wc3PathSolver: PathSolver) {
    super(canvas);

    let webgl = this.webgl;

    // Data textures.
    if (!webgl.ensureExtension('OES_texture_float')) {
      throw new Error('War3MapViewer: No float texture support!');
    }

    // Optionally used for cliff renering.
    if (!webgl.ensureExtension('OES_vertex_array_object')) {
      console.warn('War3MapViewer: No vertex array object support! This might reduce performance.');
    }

    this.on('error', (target, error, reason) => console.error(target, error, reason));

    this.addHandler(mdxHandler);

    this.wc3PathSolver = wc3PathSolver;

    this.groundShader = this.webgl.createShaderProgram(groundVert, groundFrag);
    this.waterShader = this.webgl.createShaderProgram(waterVert, waterFrag);
    this.cliffShader = this.webgl.createShaderProgram(cliffsVert, cliffsFrag);

    this.worldScene = this.addScene();

    let terrain = this.loadMapGeneric('TerrainArt\\Terrain.slk', 'text');
    let cliffTypes = this.loadMapGeneric('TerrainArt\\CliffTypes.slk', 'text');
    let water = this.loadMapGeneric('TerrainArt\\Water.slk', 'text');

    this.whenLoaded([terrain, cliffTypes, water], () => {
      this.terrainCliffsAndWaterLoaded = true;
      this.terrainData.load(terrain.data);
      this.cliffTypesData.load(cliffTypes.data);
      this.waterData.load(water.data);
      this.emit('terrainloaded');
    })

    let doodads = this.loadMapGeneric('Doodads\\Doodads.slk', 'text');
    let doodadMetaData = this.loadMapGeneric('Doodads\\DoodadMetaData.slk', 'text');
    let destructableData = this.loadMapGeneric('Units\\DestructableData.slk', 'text');
    let destructableMetaData = this.loadMapGeneric('Units\\DestructableMetaData.slk', 'text');

    this.whenLoaded([doodads, doodadMetaData, destructableData, destructableMetaData], () => {
      this.doodadsAndDestructiblesLoaded = true;
      this.doodadsData.load(doodads.data);
      this.doodadMetaData.load(doodadMetaData.data);
      this.doodadsData.load(destructableData.data);
      this.destructableMetaData.load(destructableMetaData.data);
      this.emit('doodadsloaded');
    });

    let unitData = this.loadMapGeneric('Units\\UnitData.slk', 'text');
    let unitUi = this.loadMapGeneric('Units\\unitUI.slk', 'text');
    let itemData = this.loadMapGeneric('Units\\ItemData.slk', 'text');
    let unitMetaData = this.loadMapGeneric('Units\\UnitMetaData.slk', 'text');

    this.whenLoaded([unitData, unitUi, itemData, unitMetaData], () => {
      this.unitsAndItemsLoaded = true;
      this.unitsData.load(unitData.data);
      this.unitsData.load(unitUi.data);
      this.unitsData.load(itemData.data);
      this.unitMetaData.load(unitMetaData.data);
      this.emit('unitsloaded');
    });
  }

  load(src: any) {
    return super.load(src, <PathSolver>this.mapPathSolver, this.solverParams);
  }

  loadMapGeneric(path: string, dataType: FetchDataTypeName) {
    return super.loadGeneric(urlWithParams(this.wc3PathSolver(path)[0], this.solverParams), dataType);
  }

  /**
   * Load a map from a buffer.
   */
  async loadMap(buffer: ArrayBuffer) {
    let promise = this.promise();

    // Readonly mode to optimize memory usage.
    let mapMpq = new War3Map(buffer, true);

    this.mapMpq = mapMpq;

    let wc3PathSolver = this.wc3PathSolver;

    let tileset = 'A';

    let w3iFile = mapMpq.get('war3map.w3i');

    if (w3iFile) {
      let w3iBuffer = w3iFile.arrayBuffer();

      if (w3iBuffer) {
        let w3i = new War3MapW3i(w3iBuffer);

        tileset = w3i.tileset;
      } else {
        console.warn(`Attempted to load war3map.w3i but it couldn't be decoded. Using default tileset A.`);
      }
    } else {
      console.warn(`Attempted to load war3map.w3i but it's not there. Using default tileset A.`);
    }

    this.emit('maploaded');

    this.solverParams.tileset = tileset.toLowerCase();

    this.mapPathSolver = (path, params) => {
      // MPQ paths have backwards slashes...always? Don't know.
      let mpqPath = path.replace(/\//g, '\\');

      // If the file is in the map, return it.
      let file = mapMpq.get(mpqPath);
      if (file) {
        return [file.arrayBuffer(), path.substr(path.lastIndexOf('.')), false];
      }

      // Try to get the file from the server.
      return wc3PathSolver(path, params);
    };

    let w3eFile = mapMpq.get('war3map.w3e');

    if (w3eFile) {
      let w3eBuffer = w3eFile.arrayBuffer();

      if (w3eBuffer) {
        let w3e = new War3MapW3e(w3eBuffer);
        let centerOffset = w3e.centerOffset;
        let mapSize = w3e.mapSize;

        this.corners = w3e.corners;
        this.centerOffset.set(centerOffset);
        this.mapSize.set(mapSize);

        // Override the grid based on the map.
        this.worldScene.grid = new Grid(centerOffset[0], centerOffset[1], mapSize[0] * 128 - 128, mapSize[1] * 128 - 128, 16 * 128, 16 * 128);

        this.emit('tilesetloaded');

        if (this.terrainCliffsAndWaterLoaded) {
          this.loadTerrainCliffsAndWater(w3e);
        } else {
          this.once('terrainloaded', () => this.loadTerrainCliffsAndWater(w3e));
        }
      } else {
        console.warn(`Attempted to load war3map.w3e but it couldn't be decoded. Terrain won't be rendered.`);
      }
    } else {
      console.warn(`Attempted to load war3map.w3e but it's not there. Terrain won't be rendered.`);
    }

    let modifications = this.mapMpq.readModifications();

    if (this.doodadsAndDestructiblesLoaded) {
      this.loadDoodadsAndDestructibles(modifications);
    } else {
      this.once('doodadsloaded', () => this.loadDoodadsAndDestructibles(modifications));
    }

    if (this.unitsAndItemsLoaded) {
      this.loadUnitsAndItems(modifications);
    } else {
      this.once('unitsloaded', () => this.loadUnitsAndItems(modifications));
    }

    promise.resolve();
  }

  async loadTerrainCliffsAndWater(w3e: War3MapW3e) {
    let texturesExt = this.solverParams.reforged ? '.dds' : '.blp';
    let tileset = w3e.tileset;

    for (let groundTileset of w3e.groundTilesets) {
      let row = this.terrainData.getRow(groundTileset);

      this.tilesets.push(row);
      this.tilesetTextures.push(<Texture>this.load(`${row.dir}\\${row.file}${texturesExt}`));
    }

    let blights = {
      A: 'Ashen',
      B: 'Barrens',
      C: 'Felwood',
      D: 'Cave',
      F: 'Lordf',
      G: 'Dungeon',
      I: 'Ice',
      J: 'DRuins',
      K: 'Citadel',
      L: 'Lords',
      N: 'North',
      O: 'Outland',
      Q: 'VillageFall',
      V: 'Village',
      W: 'Lordw',
      X: 'Village',
      Y: 'Village',
      Z: 'Ruins',
    };

    this.blightTextureIndex = this.tilesetTextures.length;
    this.tilesetTextures.push(<Texture>this.load(`TerrainArt\\Blight\\${blights[tileset]}_Blight${texturesExt}`));

    for (let cliffTileset of w3e.cliffTilesets) {
      let row = this.cliffTypesData.getRow(cliffTileset);

      this.cliffTilesets.push(row);
      this.cliffTextures.push(<Texture>this.load(`${row.texDir}\\${row.texFile}${texturesExt}`));
    }

    let waterRow = this.waterData.getRow(`${tileset}Sha`);

    this.waterHeightOffset = <number>waterRow.height;
    this.waterIncreasePerFrame = <number>waterRow.texRate / 60;
    this.waterTextures.length = 0;
    this.maxDeepColor.set([<number>waterRow.Dmax_R, <number>waterRow.Dmax_G, <number>waterRow.Dmax_B, <number>waterRow.Dmax_A]);
    this.minDeepColor.set([<number>waterRow.Dmin_R, <number>waterRow.Dmin_G, <number>waterRow.Dmin_B, <number>waterRow.Dmin_A]);
    this.maxShallowColor.set([<number>waterRow.Smax_R, <number>waterRow.Smax_G, <number>waterRow.Smax_B, <number>waterRow.Smax_A]);
    this.minShallowColor.set([<number>waterRow.Smin_R, <number>waterRow.Smin_G, <number>waterRow.Smin_B, <number>waterRow.Smin_A]);

    for (let i = 0, l = waterRow.numTex; i < l; i++) {
      this.waterTextures.push(<Texture>this.load(`${waterRow.texFile}${i < 10 ? '0' : ''}${i}${texturesExt}`));
    }

    await this.whenLoaded(this.tilesetTextures);

    let gl = this.gl;

    let corners = w3e.corners;
    let [columns, rows] = <Int32Array>this.mapSize;
    let centerOffset = <Float32Array>this.centerOffset;
    let instanceCount = (columns - 1) * (rows - 1);
    let cliffHeights = new Float32Array(columns * rows);
    let cornerHeights = new Float32Array(columns * rows);
    let waterHeights = new Float32Array(columns * rows);
    let cornerTextures = new Uint8Array(instanceCount * 4);
    let cornerVariations = new Uint8Array(instanceCount * 4);
    let waterFlags = new Uint8Array(instanceCount);
    let instance = 0;
    let cliffs: { [key: string]: { locations: number[], textures: number[] } } = {};

    this.columns = columns - 1;
    this.rows = rows - 1;

    for (let y = 0; y < rows; y++) {
      for (let x = 0; x < columns; x++) {
        let bottomLeft = corners[y][x];
        let index = y * columns + x;

        cliffHeights[index] = bottomLeft.groundHeight;
        cornerHeights[index] = bottomLeft.groundHeight + bottomLeft.layerHeight - 2;
        waterHeights[index] = bottomLeft.waterHeight;

        if (y < rows - 1 && x < columns - 1) {
          // Water can be used with cliffs and normal corners, so store water state regardless.
          waterFlags[instance] = this.isWater(x, y);

          // Is this a cliff, or a normal corner?
          if (this.isCliff(x, y)) {
            let bottomLeftLayer = bottomLeft.layerHeight;
            let bottomRightLayer = corners[y][x + 1].layerHeight;
            let topLeftLayer = corners[y + 1][x].layerHeight;
            let topRightLayer = corners[y + 1][x + 1].layerHeight;
            let base = Math.min(bottomLeftLayer, bottomRightLayer, topLeftLayer, topRightLayer);
            let fileName = this.cliffFileName(bottomLeftLayer, bottomRightLayer, topLeftLayer, topRightLayer, base);

            if (fileName !== 'AAAA') {
              let cliffTexture = bottomLeft.cliffTexture;

              /// ?
              if (cliffTexture === 15) {
                cliffTexture = 1;
              }

              let cliffRow = this.cliffTilesets[cliffTexture];
              let dir = cliffRow.cliffModelDir;
              let path = `Doodads\\Terrain\\${dir}\\${dir}${fileName}${getCliffVariation(dir, fileName, bottomLeft.cliffVariation)}.mdx`;

              if (!cliffs[path]) {
                cliffs[path] = { locations: [], textures: [] };
              }

              cliffs[path].locations.push((x + 1) * 128 + centerOffset[0], y * 128 + centerOffset[1], (base - 2) * 128);
              cliffs[path].textures.push(cliffTexture);
            }
          } else {
            let bottomLeftTexture = this.cornerTexture(x, y);
            let bottomRightTexture = this.cornerTexture(x + 1, y);
            let topLeftTexture = this.cornerTexture(x, y + 1);
            let topRightTexture = this.cornerTexture(x + 1, y + 1);
            let textures = unique([bottomLeftTexture, bottomRightTexture, topLeftTexture, topRightTexture]).sort();
            let texture = textures[0];

            cornerTextures[instance * 4] = texture + 1;
            cornerVariations[instance * 4] = this.getVariation(texture, bottomLeft.groundVariation);

            textures.shift();

            for (let i = 0, l = textures.length; i < l; i++) {

              let bitset = 0;

              texture = textures[i];

              if (bottomRightTexture === texture) {
                bitset |= 0b0001;
              }

              if (bottomLeftTexture === texture) {
                bitset |= 0b0010;
              }

              if (topRightTexture === texture) {
                bitset |= 0b0100;
              }

              if (topLeftTexture === texture) {
                bitset |= 0b1000;
              }

              cornerTextures[instance * 4 + 1 + i] = texture + 1;
              cornerVariations[instance * 4 + 1 + i] = bitset;
            }
          }

          instance += 1;
        }
      }
    }

    this.vertexBuffer = this.gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([0, 0, 1, 0, 0, 1, 1, 1]), gl.STATIC_DRAW);

    this.faceBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.faceBuffer);
    gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint8Array([0, 1, 2, 1, 3, 2]), gl.STATIC_DRAW);

    this.cliffHeightMap = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, this.cliffHeightMap);
    this.webgl.setTextureMode(gl.CLAMP_TO_EDGE, gl.CLAMP_TO_EDGE, gl.NEAREST, gl.NEAREST);
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.ALPHA, columns, rows, 0, gl.ALPHA, gl.FLOAT, cliffHeights);

    this.heightMap = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, this.heightMap);
    this.webgl.setTextureMode(gl.CLAMP_TO_EDGE, gl.CLAMP_TO_EDGE, gl.NEAREST, gl.NEAREST);
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.ALPHA, columns, rows, 0, gl.ALPHA, gl.FLOAT, cornerHeights);

    this.waterHeightMap = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, this.waterHeightMap);
    this.webgl.setTextureMode(gl.CLAMP_TO_EDGE, gl.CLAMP_TO_EDGE, gl.NEAREST, gl.NEAREST);
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.ALPHA, columns, rows, 0, gl.ALPHA, gl.FLOAT, waterHeights);

    this.instanceBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, this.instanceBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(instanceCount).map((currentValue, index, array) => index), gl.STATIC_DRAW);

    this.textureBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, this.textureBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, cornerTextures, gl.STATIC_DRAW);

    this.variationBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, this.variationBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, cornerVariations, gl.STATIC_DRAW);

    this.waterBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, this.waterBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, waterFlags, gl.STATIC_DRAW);

    this.terrainReady = true;
    this.anyReady = true;

    let cliffShader = <ShaderProgram>this.cliffShader;

    let cliffPromises = Object.entries(cliffs).map(async (cliff) => {
      let path = cliff[0];
      let { locations, textures } = cliff[1];
      let resource = this.loadMapGeneric(path, 'arrayBuffer');

      await resource.whenLoaded();

      return new TerrainModel(this, resource.data, locations, textures, cliffShader);
    });

    this.cliffModels = await Promise.all(cliffPromises);
    this.cliffsReady = true;
  }

  loadDoodadsAndDestructibles(modifications: any) {
    let mpq = <War3Map>this.mapMpq;
    let dooFile = mpq.get('war3map.doo');

    if (!dooFile) {
      console.warn(`Attempted to load war3map.doo but it's not there`);

      return;
    }

    let dooBuffer = dooFile.arrayBuffer();

    if (!dooBuffer) {
      console.warn(`Attempted to load war3map.doo but it couldn't be decoded`);

      return;
    }

    this.applyModificationFile(this.doodadsData, this.doodadMetaData, modifications.w3d);
    this.applyModificationFile(this.doodadsData, this.destructableMetaData, modifications.w3b);

    let doo = new War3MapDoo(dooBuffer);

    // Doodads and destructibles.
    for (let doodad of doo.doodads) {
      let row = this.doodadsData.getRow(doodad.id);
      let file = <string>row.file;
      let numVar = <number>row.numVar;

      if (file.endsWith('.mdl')) {
        file = file.slice(0, -4);
      }

      let fileVar = file;

      file += '.mdx';

      if (numVar > 1) {
        fileVar += Math.min(doodad.variation, numVar - 1);
      }

      fileVar += '.mdx';

      // First see if the model is local.
      // Doodads refering to local models may have invalid variations, so if the variation doesn't exist, try without a variation.
      let mpqFile = mpq.get(fileVar) || mpq.get(file);
      let model;

      if (mpqFile) {
        model = <MdxModel>this.load(mpqFile.name);
      } else {
        model = <MdxModel>this.load(fileVar);
      }

      this.doodads.push(new Doodad(this, model, row, doodad))
    }

    // Cliff/Terrain doodads.
    for (let doodad of doo.terrainDoodads) {
      let row = this.doodadsData.getRow(doodad.id);
      let model = <MdxModel>this.load(`${row.file}.mdx`);

      this.terrainDoodads.push(new TerrainDoodad(this, model, row, doodad));

      // let pathTexture = <Texture>this.load(row.pathTex);

      // pathTexture.whenLoaded(() => {
      //   let startx = doodad.location[0];
      //   let starty = doodad.location[1];
      //   let endx = startx + pathTexture.width / 4;
      //   let endy = starty + pathTexture.height / 4;

      //   for (let x = startx; x < endx; x++) {
      //     for (let y = starty; y < endy; y++) {

      //     }
      //   }
      // });
    }

    this.doodadsReady = true;
    this.anyReady = true;
  }

  loadUnitsAndItems(modifications: any) {
    let mpq = <War3Map>this.mapMpq;
    let dooFile = mpq.get('war3mapUnits.doo');

    if (!dooFile) {
      console.warn(`Attempted to load war3mapUnits.doo but it's not there`);

      return;
    }

    let dooBuffer = dooFile.arrayBuffer();

    if (!dooBuffer) {
      console.warn(`Attempted to load war3mapUnits.doo but it couldn't be decoded`);

      return;
    }

    this.applyModificationFile(this.unitsData, this.unitMetaData, modifications.w3u);
    this.applyModificationFile(this.unitsData, this.unitMetaData, modifications.w3t);

    let unitsDoo = new War3MapUnitsDoo(dooBuffer);

    // Collect the units and items data.
    for (let unit of unitsDoo.units) {
      let row;
      let path;

      // Hardcoded?
      if (unit.id === 'sloc') {
        path = 'Objects\\StartLocation\\StartLocation.mdx';
      } else {
        row = this.unitsData.getRow(unit.id);

        path = <string>row.file;

        if (path.endsWith('.mdl')) {
          path = path.slice(0, -4);
        }

        path += '.mdx';
      }

      if (path) {
        let model = <MdxModel>this.load(path);

        this.units.push(new Unit(this, model, row, unit));
      } else {
        console.log('Unknown unit ID', unit.id, unit);
      }
    }

    this.unitsReady = true;
    this.anyReady = true;
  }

  /**
   * Update the map.
   */
  update() {
    if (this.anyReady) {
      this.waterIndex += this.waterIncreasePerFrame;

      if (this.waterIndex >= this.waterTextures.length) {
        this.waterIndex = 0;
      }

      super.update();

      let instances = <MdxModelInstance[]>this.worldScene.instances;

      for (let instance of instances) {
        if (instance.sequenceEnded || instance.sequence === -1) {
          randomStandSequence(instance);
        }
      }
    }
  }

  /**
   * Render the map.
   */
  render() {
    if (this.anyReady) {
      let worldScene = this.worldScene;

      worldScene.startFrame();
      this.renderGround();
      this.renderCliffs();
      worldScene.renderOpaque();
      this.renderWater();
      worldScene.renderTranslucent();
    }
  }

  renderGround() {
    if (this.terrainReady) {
      let gl = this.gl;
      let webgl = this.webgl;
      let instancedArrays = <ANGLE_instanced_arrays>webgl.extensions.ANGLE_instanced_arrays
      let shader = <ShaderProgram>this.groundShader;
      let uniforms = shader.uniforms;
      let attribs = shader.attribs;
      let tilesetTextures = this.tilesetTextures;
      let instanceAttrib = attribs.a_InstanceID;
      let positionAttrib = attribs.a_position;
      let texturesAttrib = attribs.a_textures;
      let variationsAttrib = attribs.a_variations;
      let tilesetCount = tilesetTextures.length; // This includes the blight texture.

      gl.enable(gl.BLEND);
      gl.blendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA);

      webgl.useShaderProgram(shader);

      gl.uniformMatrix4fv(uniforms.u_VP, false, this.worldScene.camera.viewProjectionMatrix);
      gl.uniform2fv(uniforms.u_offset, <Float32Array>this.centerOffset);
      gl.uniform2f(uniforms.u_size, this.columns, this.rows);
      gl.uniform1i(uniforms.u_heightMap, 15);

      gl.activeTexture(gl.TEXTURE15);
      gl.bindTexture(gl.TEXTURE_2D, this.heightMap);

      gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
      gl.vertexAttribPointer(positionAttrib, 2, gl.FLOAT, false, 0, 0);

      gl.bindBuffer(gl.ARRAY_BUFFER, this.instanceBuffer);
      gl.vertexAttribPointer(instanceAttrib, 1, gl.FLOAT, false, 0, 0);
      instancedArrays.vertexAttribDivisorANGLE(instanceAttrib, 1);

      gl.bindBuffer(gl.ARRAY_BUFFER, this.textureBuffer);
      gl.vertexAttribPointer(texturesAttrib, 4, gl.UNSIGNED_BYTE, false, 0, 0);
      instancedArrays.vertexAttribDivisorANGLE(texturesAttrib, 1);

      gl.bindBuffer(gl.ARRAY_BUFFER, this.variationBuffer);
      gl.vertexAttribPointer(variationsAttrib, 4, gl.UNSIGNED_BYTE, false, 0, 0);
      instancedArrays.vertexAttribDivisorANGLE(variationsAttrib, 1);

      gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.faceBuffer);

      gl.uniform1f(uniforms.u_baseTileset, 0);

      for (let i = 0, l = Math.min(tilesetCount, 15); i < l; i++) {
        let isExtended = tilesetTextures[i].width > tilesetTextures[i].height ? 1 : 0;

        gl.uniform1f(uniforms[`u_extended[${i}]`], isExtended);
        gl.uniform1i(uniforms[`u_tilesets[${i}]`], i);

        tilesetTextures[i].bind(i);
      }

      instancedArrays.drawElementsInstancedANGLE(gl.TRIANGLES, 6, gl.UNSIGNED_BYTE, 0, this.rows * this.columns);

      if (tilesetCount > 15) {
        gl.uniform1f(uniforms.u_baseTileset, 15);

        for (let i = 0, l = tilesetCount - 15; i < l; i++) {
          let isExtended = tilesetTextures[i + 15].width > tilesetTextures[i + 15].height ? 1 : 0;

          gl.uniform1f(uniforms[`u_extended[${i}]`], isExtended);

          tilesetTextures[i + 15].bind(i);
        }

        instancedArrays.drawElementsInstancedANGLE(gl.TRIANGLES, 6, gl.UNSIGNED_BYTE, 0, this.rows * this.columns);
      }

      instancedArrays.vertexAttribDivisorANGLE(texturesAttrib, 0);
      instancedArrays.vertexAttribDivisorANGLE(variationsAttrib, 0);
      instancedArrays.vertexAttribDivisorANGLE(instanceAttrib, 0);
    }
  }

  renderWater() {
    if (this.terrainReady) {
      let gl = this.gl;
      let webgl = this.webgl;
      let instancedArrays = <ANGLE_instanced_arrays>webgl.extensions.ANGLE_instanced_arrays
      let shader = <ShaderProgram>this.waterShader;
      let uniforms = shader.uniforms;
      let attribs = shader.attribs;
      let instanceAttrib = attribs.a_InstanceID;
      let positionAttrib = attribs.a_position;
      let isWaterAttrib = attribs.a_isWater;

      gl.depthMask(false);

      gl.enable(gl.BLEND);
      gl.blendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA);

      webgl.useShaderProgram(shader);

      gl.uniformMatrix4fv(uniforms.u_VP, false, this.worldScene.camera.viewProjectionMatrix);
      gl.uniform2fv(uniforms.u_offset, <Float32Array>this.centerOffset);
      gl.uniform2f(uniforms.u_size, this.columns, this.rows);
      gl.uniform1i(uniforms.u_heightMap, 0);
      gl.uniform1i(uniforms.u_waterHeightMap, 1);
      gl.uniform1i(uniforms.u_waterTexture, 2);
      gl.uniform1f(uniforms.u_offsetHeight, this.waterHeightOffset);
      gl.uniform4fv(uniforms.u_maxDeepColor, this.maxDeepColor);
      gl.uniform4fv(uniforms.u_minDeepColor, this.minDeepColor);
      gl.uniform4fv(uniforms.u_maxShallowColor, this.maxShallowColor);
      gl.uniform4fv(uniforms.u_minShallowColor, this.minShallowColor);

      gl.activeTexture(gl.TEXTURE0);
      gl.bindTexture(gl.TEXTURE_2D, this.heightMap);

      gl.activeTexture(gl.TEXTURE1);
      gl.bindTexture(gl.TEXTURE_2D, this.waterHeightMap);

      this.waterTextures[this.waterIndex | 0].bind(2);

      gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
      gl.vertexAttribPointer(positionAttrib, 2, gl.FLOAT, false, 8, 0);

      gl.bindBuffer(gl.ARRAY_BUFFER, this.instanceBuffer);
      gl.vertexAttribPointer(instanceAttrib, 1, gl.FLOAT, false, 4, 0);
      instancedArrays.vertexAttribDivisorANGLE(instanceAttrib, 1);

      gl.bindBuffer(gl.ARRAY_BUFFER, this.waterBuffer);
      gl.vertexAttribPointer(isWaterAttrib, 1, gl.UNSIGNED_BYTE, false, 1, 0);
      instancedArrays.vertexAttribDivisorANGLE(isWaterAttrib, 1);

      gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.faceBuffer);
      instancedArrays.drawElementsInstancedANGLE(gl.TRIANGLES, 6, gl.UNSIGNED_BYTE, 0, this.rows * this.columns);

      instancedArrays.vertexAttribDivisorANGLE(isWaterAttrib, 0);
      instancedArrays.vertexAttribDivisorANGLE(instanceAttrib, 0);
    }
  }

  renderCliffs() {
    if (this.cliffsReady) {
      let gl = this.gl;
      let webgl = this.webgl;
      let instancedArrays = <ANGLE_instanced_arrays>webgl.extensions.ANGLE_instanced_arrays
      let vertexArrayObject = <OES_vertex_array_object>webgl.extensions.OES_vertex_array_object;
      let shader = <ShaderProgram>this.cliffShader;
      let attribs = shader.attribs;
      let uniforms = shader.uniforms;

      gl.disable(gl.BLEND);

      shader.use();

      gl.uniformMatrix4fv(uniforms.u_VP, false, this.worldScene.camera.viewProjectionMatrix);
      gl.uniform1i(uniforms.u_heightMap, 0);
      gl.uniform2f(uniforms.u_pixel, 1 / (this.columns + 1), 1 / (this.rows + 1));
      gl.uniform2fv(uniforms.u_centerOffset, <Float32Array>this.centerOffset);
      gl.uniform1i(uniforms.u_texture1, 1);
      gl.uniform1i(uniforms.u_texture2, 2);

      gl.activeTexture(gl.TEXTURE0);
      gl.bindTexture(gl.TEXTURE_2D, this.cliffHeightMap);

      gl.activeTexture(gl.TEXTURE1);
      gl.bindTexture(gl.TEXTURE_2D, this.cliffTextures[0].webglResource);

      if (this.cliffTextures.length > 1) {
        gl.activeTexture(gl.TEXTURE2);
        gl.bindTexture(gl.TEXTURE_2D, this.cliffTextures[1].webglResource);
      }

      // Set instanced attributes.
      if (!vertexArrayObject) {
        instancedArrays.vertexAttribDivisorANGLE(attribs.a_instancePosition, 1);
        instancedArrays.vertexAttribDivisorANGLE(attribs.a_instanceTexture, 1);
      }

      // Render the cliffs.
      for (let cliff of this.cliffModels) {
        cliff.render(shader);
      }

      // Clear instanced attributes.
      if (!vertexArrayObject) {
        instancedArrays.vertexAttribDivisorANGLE(attribs.a_instancePosition, 0);
        instancedArrays.vertexAttribDivisorANGLE(attribs.a_instanceTexture, 0);
      }
    }
  }

  cliffFileName(bottomLeftLayer: number, bottomRightLayer: number, topLeftLayer: number, topRightLayer: number, base: number) {
    return String.fromCharCode(65 + bottomLeftLayer - base) +
      String.fromCharCode(65 + topLeftLayer - base) +
      String.fromCharCode(65 + topRightLayer - base) +
      String.fromCharCode(65 + bottomRightLayer - base);
  }

  getVariation(groundTexture: number, variation: number) {
    let texture = this.tilesetTextures[groundTexture];

    // Extended?
    if (texture.width > texture.height) {
      if (variation < 16) {
        return 16 + variation;
      } else if (variation === 16) {
        return 15;
      } else {
        return 0;
      }
    } else {
      if (variation === 0) {
        return 0;
      } else {
        return 15;
      }
    }
  }

  /**
   * Is the corner at the given column and row a cliff?
   */
  isCliff(column: number, row: number) {
    if (column < 1 || column > this.columns - 1 || row < 1 || row > this.rows - 1) {
      return false;
    }

    let corners = this.corners;
    let bottomLeft = corners[row][column].layerHeight;
    let bottomRight = corners[row][column + 1].layerHeight;
    let topLeft = corners[row + 1][column].layerHeight;
    let topRight = corners[row + 1][column + 1].layerHeight;

    return bottomLeft !== bottomRight || bottomLeft !== topLeft || bottomLeft !== topRight;
  }

  /**
   * Is the tile at the given column and row water?
   */
  isWater(column: number, row: number) {
    let corners = this.corners;

    return corners[row][column].water || corners[row][column + 1].water || corners[row + 1][column].water || corners[row + 1][column + 1].water;
  }

  /**
   * Given a cliff index, get its ground texture index.
   * This is an index into the tilset textures.
   */
  cliffGroundIndex(whichCliff: number) {
    let whichTileset = this.cliffTilesets[whichCliff].groundTile;
    let tilesets = this.tilesets;

    for (let i = 0, l = tilesets.length; i < l; i++) {
      if (tilesets[i].tileID === whichTileset) {
        return i;
      }
    }
  }

  /**
   * Get the ground texture of a corner, whether it's normal ground, a cliff, or a blighted corner.
   */
  cornerTexture(column: number, row: number) {
    let corners = this.corners;
    let columns = this.columns;
    let rows = this.rows;

    for (let y = -1; y < 1; y++) {
      for (let x = -1; x < 1; x++) {
        if (column + x > 0 && column + x < columns - 1 && row + y > 0 && row + y < rows - 1) {
          if (this.isCliff(column + x, row + y)) {
            let texture = corners[row + y][column + x].cliffTexture;

            if (texture === 15) {
              texture = 1;
            }

            return this.cliffGroundIndex(texture);
          }
        }
      }
    }

    let corner = corners[row][column];

    // Is this corner blighted?
    if (corner.blight) {
      return this.blightTextureIndex;
    }

    return corner.groundTexture;
  }

  applyModificationFile(dataMap: MappedData, metadataMap: MappedData, modificationFile: any) {
    if (modificationFile) {
      // Modifications to built-in objects
      this.applyModificationTable(dataMap, metadataMap, modificationFile.originalTable);

      // Declarations of user-defined objects
      this.applyModificationTable(dataMap, metadataMap, modificationFile.customTable);
    }
  }

  applyModificationTable(dataMap: MappedData, metadataMap: MappedData, modificationTable: any) {
    for (let modificationObject of modificationTable.objects) {
      let row;

      if (modificationObject.newId !== '') {
        row = dataMap.getRow(modificationObject.newId);

        if (!row) {
          row = { ...dataMap.getRow(modificationObject.oldId) };

          dataMap.setRow(modificationObject.newId, row);
        }
      } else {
        row = dataMap.getRow(modificationObject.oldId);
      }

      for (let modification of modificationObject.modifications) {
        let metadata = metadataMap.getRow(modification.id);

        if (metadata) {
          row[<string>metadata.field] = modification.value;
        } else {
          console.warn('Unknown modification ID', modification);
        }
      }
    }
  }

  groundNormal(out: vec3, x: number, y: number) {
    let centerOffset = <Float32Array>this.centerOffset;
    let mapSize = <Int32Array>this.mapSize;

    x = (x - centerOffset[0]) / 128;
    y = (y - centerOffset[1]) / 128;

    let cellX = x | 0;
    let cellY = y | 0;

    // See if this coordinate is in the map
    if (cellX >= 0 && cellX < mapSize[0] - 1 && cellY >= 0 && cellY < mapSize[1] - 1) {
      // See http://gamedev.stackexchange.com/a/24574
      let corners = this.corners;
      let bottomLeft = corners[cellY][cellX].groundHeight;
      let bottomRight = corners[cellY][cellX + 1].groundHeight;
      let topLeft = corners[cellY + 1][cellX].groundHeight;
      let topRight = corners[cellY + 1][cellX + 1].groundHeight;
      let sqX = x - cellX;
      let sqY = y - cellY;

      if (sqX + sqY < 1) {
        vec3.set(normalHeap1, 1, 0, bottomRight - bottomLeft);
        vec3.set(normalHeap2, 0, 1, topLeft - bottomLeft);
      } else {
        vec3.set(normalHeap1, -1, 0, topRight - topLeft);
        vec3.set(normalHeap2, 0, 1, topRight - bottomRight);
      }

      vec3.normalize(out, vec3.cross(out, normalHeap1, normalHeap2));
    } else {
      vec3.set(out, 0, 0, 1);
    }

    return out;
  }
}

/*
  heightAt(location) {
    let heightMap = this.heightMap,
      offset = this.offset,
      x = (location[0] / 128) + offset[0],
      y = (location[1] / 128) + offset[1];

    let minY = Math.floor(y),
      maxY = Math.ceil(y),
      minX = Math.floor(x),
      maxX = Math.ceil(x);

    // See if this coordinate is in the map
    if (maxY > 0 && minY < heightMap.length - 1 && maxX > 0 && minX < heightMap[0].length - 1) {
      // See http://gamedev.stackexchange.com/a/24574
      let triZ0 = heightMap[minY][minX],
        triZ1 = heightMap[minY][maxX],
        triZ2 = heightMap[maxY][minX],
        triZ3 = heightMap[maxY][maxX],
        sqX = x - minX,
        sqZ = y - minY,
        height;

      if ((sqX + sqZ) < 1) {
        height = triZ0 + (triZ1 - triZ0) * sqX + (triZ2 - triZ0) * sqZ;
      } else {
        height = triZ3 + (triZ1 - triZ3) * (1 - sqZ) + (triZ2 - triZ3) * (1 - sqX);
      }

      return height * 128;
    }

    return 0;
  }
  */