glUtils.js

// augment Sylvester some
Matrix.Translation = function(v) {
  if (v.elements.length == 2) {
    var r = Matrix.I(3);
    r.elements[2][0] = v.elements[0];
    r.elements[2][1] = v.elements[1];
    return r;
  }
  
  if (v.elements.length == 3) {
    var r = Matrix.I(4);
    r.elements[0][3] = v.elements[0];
    r.elements[1][3] = v.elements[1];
    r.elements[2][3] = v.elements[2];
    return r;
  }
  
  throw "Invalid length for Translation";
}

Matrix.prototype.flatten = function() {
  var result = [];
  if (this.elements.length == 0)     
    return [];
  
  
  for (var j = 0; j < this.elements[0].length; j++) 
    for (var i = 0; i < this.elements.length; i++) 
      result.push(this.elements[i][j]);
  return result;
}

Matrix.prototype.ensure4x4 = function() {
  if (this.elements.length == 4 &&
  this.elements[0].length == 4)     
    return this;
  
  if (this.elements.length > 4 ||
  this.elements[0].length > 4)     
    return null;
  
  for (var i = 0; i < this.elements.length; i++) {
    for (var j = this.elements[i].length; j < 4; j++) {
      if (i == j) 
        this.elements[i].push(1);
      else 
        this.elements[i].push(0);
    }
  }
  
  for (var i = this.elements.length; i < 4; i++) {
    if (i == 0) 
      this.elements.push([1, 0, 0, 0]);
    else 
      if (i == 1) 
        this.elements.push([0, 1, 0, 0]);
      else 
        if (i == 2) 
          this.elements.push([0, 0, 1, 0]);
        else 
          if (i == 3) this.elements.push([0, 0, 0, 1]);
  }
  
  return this;
};

Matrix.prototype.make3x3 = function() {
  if (this.elements.length != 4 ||
  this.elements[0].length != 4)     
    return null;
  
  return Matrix.create([[this.elements[0][0], this.elements[0][1], this.elements[0][2]], [this.elements[1][0], this.elements[1][1], this.elements[1][2]], [this.elements[2][0], this.elements[2][1], this.elements[2][2]]]);
};

Vector.prototype.flatten = function() {
  return this.elements;
};

function mht(m) {
  var s = "";
  if (m.length == 16) {
    for (var i = 0; i < 4; i++) {
      s += "<span style='font-family: monospace'>[" + m[i * 4 + 0].toFixed(4) + "," + m[i * 4 + 1].toFixed(4) + "," + m[i * 4 + 2].toFixed(4) + "," + m[i * 4 + 3].toFixed(4) + "]</span><br>";
    }
  }
  else 
    if (m.length == 9) {
      for (var i = 0; i < 3; i++) {
        s += "<span style='font-family: monospace'>[" + m[i * 3 + 0].toFixed(4) + "," + m[i * 3 + 1].toFixed(4) + "," + m[i * 3 + 2].toFixed(4) + "]</font><br>";
      }
    }
    else {
      return m.toString();
    }
  return s;
}

//
// gluLookAt
//
function makeLookAt(ex, ey, ez, cx, cy, cz, ux, uy, uz) {
  var eye = $V([ex, ey, ez]);
  var center = $V([cx, cy, cz]);
  var up = $V([ux, uy, uz]);
  
  var mag;
  
  var z = eye.subtract(center).toUnitVector();
  var x = up.cross(z).toUnitVector();
  var y = z.cross(x).toUnitVector();
  
  var m = $M([[x.e(1), x.e(2), x.e(3), 0], [y.e(1), y.e(2), y.e(3), 0], [z.e(1), z.e(2), z.e(3), 0], [0, 0, 0, 1]]);
  
  var t = $M([[1, 0, 0, -ex], [0, 1, 0, -ey], [0, 0, 1, -ez], [0, 0, 0, 1]]);
  return m.x(t);
}

//
// glOrtho
//
function makeOrtho(left, right, bottom, top, znear, zfar) {
  var tx = -(right + left) / (right - left);
  var ty = -(top + bottom) / (top - bottom);
  var tz = -(zfar + znear) / (zfar - znear);
  
  return $M([[2 / (right - left), 0, 0, tx], [0, 2 / (top - bottom), 0, ty], [0, 0, -2 / (zfar - znear), tz], [0, 0, 0, 1]]);
}

//
// gluPerspective
//
function makePerspective(fovy, aspect, znear, zfar) {
  var ymax = znear * Math.tan(fovy * Math.PI / 360.0);
  var ymin = -ymax;
  var xmin = ymin * aspect;
  var xmax = ymax * aspect;
  
  return makeFrustum(xmin, xmax, ymin, ymax, znear, zfar);
}

//
// glFrustum
//
function makeFrustum(left, right, bottom, top, znear, zfar) {
  var X = 2 * znear / (right - left);
  var Y = 2 * znear / (top - bottom);
  var A = (right + left) / (right - left);
  var B = (top + bottom) / (top - bottom);
  var C = -(zfar + znear) / (zfar - znear);
  var D = -2 * zfar * znear / (zfar - znear);
  
  return $M([[X, 0, A, 0], [0, Y, B, 0], [0, 0, C, D], [0, 0, -1, 0]]);
}

//
// glOrtho
//
function makeOrtho(left, right, bottom, top, znear, zfar) {
  var tx = -(right + left) / (right - left);
  var ty = -(top + bottom) / (top - bottom);
  var tz = -(zfar + znear) / (zfar - znear);
  
  return $M([[2 / (right - left), 0, 0, tx], [0, 2 / (top - bottom), 0, ty], [0, 0, -2 / (zfar - znear), tz], [0, 0, 0, 1]]);
}