PolyhedronGeometry constructor

PolyhedronGeometry(dynamic vertices, dynamic indices, [ dynamic radius = 1, dynamic detail = 0, ])

Implementation

PolyhedronGeometry(vertices, indices, [radius = 1, detail = 0]) : super() {
  type = "PolyhedronGeometry";
  // default buffer data
  List<double> vertexBuffer = [];
  List<double> uvBuffer = [];

  // helper functions ----------------- start
  void pushVertex(vertex) {
    vertexBuffer.addAll([vertex.x, vertex.y, vertex.z]);
  }

  void subdivideFace(Vector3 a, Vector3 b, Vector3 c, detail) {
    var cols = detail + 1;

    // we use this multidimensional array as a data structure for creating the subdivision

    List<List<Vector3>> v = List<List<Vector3>>.filled(cols + 1, []);

    // construct all of the vertices for this subdivision

    for (var i = 0; i <= cols; i++) {
      var aj = a.clone().lerp(c, i / cols);
      var bj = b.clone().lerp(c, i / cols);

      var rows = cols - i;

      v[i] = List<Vector3>.filled(rows + 1, Vector3.init());

      for (var j = 0; j <= rows; j++) {
        if (j == 0 && i == cols) {
          v[i][j] = aj;
        } else {
          v[i][j] = aj.clone().lerp(bj, j / rows);
        }
      }
    }

    // construct all of the faces

    for (var i = 0; i < cols; i++) {
      for (var j = 0; j < 2 * (cols - i) - 1; j++) {
        int k = Math.floor(j / 2).toInt();

        if (j % 2 == 0) {
          pushVertex(v[i][k + 1]);
          pushVertex(v[i + 1][k]);
          pushVertex(v[i][k]);
        } else {
          pushVertex(v[i][k + 1]);
          pushVertex(v[i + 1][k + 1]);
          pushVertex(v[i + 1][k]);
        }
      }
    }
  }

  void getVertexByIndex(index, vertex) {
    var stride = index * 3;

    vertex.x = vertices[stride + 0].toDouble();
    vertex.y = vertices[stride + 1].toDouble();
    vertex.z = vertices[stride + 2].toDouble();
  }

  void subdivide(detail) {
    var a = Vector3.init();
    var b = Vector3.init();
    var c = Vector3.init();

    // iterate over all faces and apply a subdivison with the given detail value

    for (var i = 0; i < indices.length; i += 3) {
      // get the vertices of the face

      getVertexByIndex(indices[i + 0], a);
      getVertexByIndex(indices[i + 1], b);
      getVertexByIndex(indices[i + 2], c);

      // perform subdivision

      subdivideFace(a, b, c, detail);
    }
  }

  void applyRadius(radius) {
    var vertex = Vector3.init();

    // iterate over the entire buffer and apply the radius to each vertex

    for (var i = 0; i < vertexBuffer.length; i += 3) {
      vertex.x = vertexBuffer[i + 0];
      vertex.y = vertexBuffer[i + 1];
      vertex.z = vertexBuffer[i + 2];

      vertex.normalize().multiplyScalar(radius);

      vertexBuffer[i + 0] = vertex.x.toDouble();
      vertexBuffer[i + 1] = vertex.y.toDouble();
      vertexBuffer[i + 2] = vertex.z.toDouble();
    }
  }

  void correctUV(uv, stride, vector, azimuth) {
    if ((azimuth < 0) && (uv.x == 1)) {
      uvBuffer[stride] = uv.x - 1;
    }

    if ((vector.x == 0) && (vector.z == 0)) {
      uvBuffer[stride] = azimuth / 2 / Math.pi + 0.5;
    }
  }

  // Angle around the Y axis, counter-clockwise when looking from above.

  azimuth(vector) {
    return Math.atan2(vector.z, -vector.x);
  }

  // Angle above the XZ plane.

  inclination(vector) {
    return Math.atan2(-vector.y, Math.sqrt((vector.x * vector.x) + (vector.z * vector.z)));
  }

  correctUVs() {
    var a = Vector3.init();
    var b = Vector3.init();
    var c = Vector3.init();

    var centroid = Vector3.init();

    var uvA = Vector2(null, null);
    var uvB = Vector2(null, null);
    var uvC = Vector2(null, null);

    for (var i = 0, j = 0; i < vertexBuffer.length; i += 9, j += 6) {
      a.set(vertexBuffer[i + 0], vertexBuffer[i + 1], vertexBuffer[i + 2]);
      b.set(vertexBuffer[i + 3], vertexBuffer[i + 4], vertexBuffer[i + 5]);
      c.set(vertexBuffer[i + 6], vertexBuffer[i + 7], vertexBuffer[i + 8]);

      uvA.set(uvBuffer[j + 0], uvBuffer[j + 1]);
      uvB.set(uvBuffer[j + 2], uvBuffer[j + 3]);
      uvC.set(uvBuffer[j + 4], uvBuffer[j + 5]);

      centroid.copy(a).add(b).add(c).divideScalar(3);

      var azi = azimuth(centroid);

      correctUV(uvA, j + 0, a, azi);
      correctUV(uvB, j + 2, b, azi);
      correctUV(uvC, j + 4, c, azi);
    }
  }

  correctSeam() {
    // handle case when face straddles the seam, see #3269

    for (var i = 0; i < uvBuffer.length; i += 6) {
      // uv data of a single face

      var x0 = uvBuffer[i + 0];
      var x1 = uvBuffer[i + 2];
      var x2 = uvBuffer[i + 4];

      var max = Math.max3(x0, x1, x2);
      var min = Math.min3(x0, x1, x2);

      // 0.9 is somewhat arbitrary

      if (max > 0.9 && min < 0.1) {
        if (x0 < 0.2) uvBuffer[i + 0] += 1;
        if (x1 < 0.2) uvBuffer[i + 2] += 1;
        if (x2 < 0.2) uvBuffer[i + 4] += 1;
      }
    }
  }

  generateUVs() {
    var vertex = Vector3.init();

    for (var i = 0; i < vertexBuffer.length; i += 3) {
      vertex.x = vertexBuffer[i + 0];
      vertex.y = vertexBuffer[i + 1];
      vertex.z = vertexBuffer[i + 2];

      var u = azimuth(vertex) / 2 / Math.pi + 0.5;
      double v = inclination(vertex) / Math.pi + 0.5;
      uvBuffer.addAll([u, 1 - v]);
    }

    correctUVs();

    correctSeam();
  }

  // helper functions ----------------- end

  parameters = {"vertices": vertices, "indices": indices, "radius": radius, "detail": detail};

  // the subdivision creates the vertex buffer data

  subdivide(detail);

  // all vertices should lie on a conceptual sphere with a given radius

  applyRadius(radius);

  // finally, create the uv data

  generateUVs();

  // build non-indexed geometry

  setAttribute('position', Float32BufferAttribute(Float32Array.from(vertexBuffer), 3, false));
  setAttribute('normal', Float32BufferAttribute(Float32Array.from(slice<double>(vertexBuffer, 0)), 3, false));
  setAttribute('uv', Float32BufferAttribute(Float32Array.from(uvBuffer), 2, false));

  if (detail == 0) {
    computeVertexNormals(); // flat normals

  } else {
    normalizeNormals(); // smooth normals

  }
}