rojs/lib/render/gat.ts

import { mat4, vec3, vec4 } from "gl-matrix";

import { Corner, GAT, Tile } from "../format/gat";
import { createProgram, createShader, ShaderType } from "../util/render";

/* @ts-ignore */
import fragmentSource from "./gat.frag";
/* @ts-ignore */
import vertexSource from "./gat.vert";

const ORIGIN = vec4.fromValues(0, 0, 0, 1);
const UP = vec3.fromValues(0, 1, 0);

const printMat4 = (name: string, m: mat4) => {
  console.log(name);
  console.log([m[0], m[4], m[8], m[12]]);
  console.log([m[1], m[5], m[9], m[13]]);
  console.log([m[2], m[6], m[10], m[11]]);
  console.log([m[3], m[7], m[14], m[15]]);
};

// Function to download data to a file
function download(data: BlobPart, filename: string, type: string) {
  var file = new Blob([data], { type: type });
  // Others
  var a = document.createElement("a"),
    url = URL.createObjectURL(file);
  a.href = url;
  a.download = filename;
  document.body.appendChild(a);
  a.click();
  setTimeout(function () {
    document.body.removeChild(a);
    window.URL.revokeObjectURL(url);
  }, 0);
}

const exportObj = (vertices: number[]): string => {
  let obj = "";
  for (let i = 0; i < vertices.length / 3; ++i) {
    obj += `v ${vertices[i]} ${vertices[i + 1]} ${vertices[i + 2]}\n`;
  }
  for (let i = 0; i < vertices.length / (3 * 2); ++i) {
    obj += `f ${i + 1} ${i + 2} ${i + 3}\n`;
    obj += `f ${i + 4} ${i + 5} ${i + 6}\n`;
  }
  return obj;
};

export const renderGAT = (gl: WebGLRenderingContext, gat: GAT) => {
  console.log("gat", gat);

  const fragmentShader = createShader(gl, ShaderType.FRAGMENT, fragmentSource);
  const vertexShader = createShader(gl, ShaderType.VERTEX, vertexSource);
  const program = createProgram(gl, vertexShader, fragmentShader);

  gl.useProgram(program);
  gl.enable(gl.DEPTH_TEST);

  const maxAltitude = getMaxAltitude(gat);
  console.log("altitude", maxAltitude);

  const camera = vec3.fromValues(
    gat.width / 2,
    maxAltitude + 10,
    gat.height / 2
  );
  console.log("camera", camera);

  const centerX = Math.floor(gat.width / 2);
  const centerZ = Math.floor(gat.height / 2);
  const centerTile = gat.tiles[gat.width * centerZ + centerX];
  const center = vec3.fromValues(centerX, avgTileHeight(centerTile), centerZ);
  console.log("center", center);

  const model = mat4.create();
  mat4.translate(
    model,
    model,
    vec3.fromValues(-camera[0], -camera[1], -camera[2])
  );

  const view = mat4.create();
  mat4.rotateX(view, view, -Math.PI / 2);
  // mat4.lookAt(view, camera, center, UP);

  const modelview = model;
  mat4.multiply(modelview, view, model);

  const perspective = mat4.create();
  const aspect = gl.canvas.clientWidth / gl.canvas.clientHeight;
  mat4.perspective(perspective, Math.PI / 4, aspect, -0.5, 1000);

  const matrix = mat4.create();
  mat4.multiply(matrix, modelview, perspective);

  const matrixLoc = gl.getUniformLocation(program, "u_matrix");
  gl.uniformMatrix4fv(matrixLoc, false, matrix);

  printMat4("model", model);
  printMat4("view", view);
  printMat4("view * model", modelview);
  printMat4("projection", perspective);
  printMat4("projection * view * model", matrix);

  const origin = vec4.create();
  vec4.transformMat4(origin, ORIGIN, model);
  console.log("origin (model)", origin);
  vec4.transformMat4(origin, ORIGIN, modelview);
  console.log("origin (modelview)", origin);
  vec4.transformMat4(origin, ORIGIN, matrix);
  console.log("origin (projection)", origin);

  const vertices: number[] = [];

  gat.tiles.forEach((tile, i) => {
    const x = i % gat.width;
    const z = Math.floor(i / gat.width);

    const topLeft = [x, tile.altitude[Corner.TOP_LEFT], z];
    const topRight = [x + 1, tile.altitude[Corner.TOP_RIGHT], z];
    const bottomLeft = [x, tile.altitude[Corner.BOTTOM_LEFT], z + 1];
    const bottomRight = [x + 1, tile.altitude[Corner.BOTTOM_RIGHT], z + 1];

    vertices.push(
      ...topLeft,
      ...bottomLeft,
      ...topRight,
      ...topRight,
      ...bottomLeft,
      ...bottomRight
    );
  });

  console.log("# vertices", vertices.length / 3);

  // download(exportObj(vertices), "heightmap.obj", "text/plain");

  let failCount = 0;
  for (let i = 0; i < vertices.length / 3; ++i) {
    const vec = vec4.fromValues(
      vertices[i],
      vertices[i + 1],
      vertices[i + 2],
      1
    );
    const result = checkPixelCoord(vec, matrix);
    if (result) {
      if (failCount < 10) {
        console.log("vertex clipped, (pre-xform)", vec, "(post-xform)", result);
      }
      failCount++;
    }
  }
  console.log("clipCount", failCount);
  console.log("totalCount", vertices.length / 3);

  const vertexBuffer = gl.createBuffer();
  gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);

  const positionLoc = gl.getAttribLocation(program, "a_position");
  gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
  gl.vertexAttribPointer(positionLoc, 3, gl.FLOAT, false, 0, 0);
  gl.enableVertexAttribArray(positionLoc);

  gl.clearColor(0, 0, 0, 1);
  gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
  gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);

  gl.drawArrays(gl.TRIANGLES, 0, vertices.length / 3);
};

const checkPixelCoord = (x: vec4, mat: mat4): vec4 | null => {
  const vec = vec4.create();
  vec4.transformMat4(vec, x, mat);
  for (let i = 0; i < vec.length; ++i) {
    if (Math.abs(vec[i]) >= 1) {
      return vec;
    }
  }
  return null;
};

const getMaxAltitude = (gat: GAT): number =>
  gat.tiles.reduce(
    (max, tile) =>
      Object.values(tile.altitude).reduce(
        (max1, altitude) => Math.max(max1, altitude),
        max
      ),
    0
  );

const avgTileHeight = (tile: Tile): number => {
  const heights = [...Object.values(tile.altitude)];
  const s = heights.reduce((x, y) => x + y, 0);
  return s / heights.length;
};