• Cube.js

  • ¶

    Cube geometry generator.

  • ¶

    Parent class : geom.Geometry

  • ¶

    Example use

     var g = new Cube(1, 1, 1, 10, 10, 10);
 var mesh = new Mesh(g, new materials.SolidColor());

    var geom = require('pex-geom');
var Vec2 = geom.Vec2;
var Vec3 = geom.Vec3;
var Geometry = geom.Geometry;
  • ¶

    Cube ( sx, sy, sz, nx, ny, nz )

    sx - size x / width { Number = 1 }
    sy - size y / height { Number = 1 }
    sz - size z / depth { Number = 1 }
    nx - number of subdivisions on x axis { Number/Int = 1 }
    ny - number of subdivisions on y axis { Number/Int = 1 }
    nz - number of subdivisions on z axis { Number/Int = 1 }

    function Cube(sx, sy, sz, nx, ny, nz) {
  sx = sx != null ? sx : 1;
  sy = sy != null ? sy : sx != null ? sx : 1;
  sz = sz != null ? sz : sx != null ? sx : 1;
  nx = nx || 1;
  ny = ny || 1;
  nz = nz || 1;

  Geometry.call(this, { vertices: true, normals: true, texCoords: true, faces: true });

  var vertices = this.vertices;
  var texCoords = this.texCoords;
  var normals = this.normals;
  var faces = this.faces;

  var vertexIndex = 0;
  • ¶

    How faces are constructed:

    0-----1 . . 2       n  <----  n+1
|   / .     .       |         A
| /   .     .       V         |
3 . . 4 . . 5      n+nu --> n+nu+1
.     .     .
.     .     .
6 . . 7 . . 8

      function makePlane(u, v, w, su, sv, nu, nv, pw, flipu, flipv) {
    var vertShift = vertexIndex;
    for (var j=0; j<=nv; j++) {
      for (var i=0; i<=nu; i++) {
        vert = vertices[vertexIndex] = Vec3.create();
        vert[u] = (-su / 2 + i * su / nu) * flipu;
        vert[v] = (-sv / 2 + j * sv / nv) * flipv;
        vert[w] = pw;
        normal = normals[vertexIndex] = Vec3.create();
        normal[u] = 0;
        normal[v] = 0;
        normal[w] = pw / Math.abs(pw);
        texCoord = texCoords[vertexIndex] = Vec2.create();
        texCoord.x = i / nu;
        texCoord.y = 1.0 - j / nv;
        ++vertexIndex;
      }
    }
    for (var j=0; j<=nv-1; j++) {
      for (var i=0; i<=nu-1; i++) {
        var n = vertShift + j * (nu + 1) + i;
        faces.push([n, n + nu + 1, n + nu + 2, n + 1]);
      }
    }
  }

  makePlane('x', 'y', 'z', sx, sy, nx, ny, sz / 2, 1, -1);
  makePlane('x', 'y', 'z', sx, sy, nx, ny, -sz / 2, -1, -1);
  makePlane('z', 'y', 'x', sz, sy, nz, ny, -sx / 2, 1, -1);
  makePlane('z', 'y', 'x', sz, sy, nz, ny, sx / 2, -1, -1);
  makePlane('x', 'z', 'y', sx, sz, nx, nz, sy / 2, 1, 1);
  makePlane('x', 'z', 'y', sx, sz, nx, nz, -sy / 2, 1, -1);

  this.computeEdges();
}

Cube.prototype = Object.create(Geometry.prototype);

module.exports = Cube;