/Demo/glUtils.js

  1// augment Sylvester some
  2Matrix.Translation = function (v)
  3{
  4  if (v.elements.length == 2) {
  5    var r = Matrix.I(3);
  6    r.elements[2][0] = v.elements[0];
  7    r.elements[2][1] = v.elements[1];
  8    return r;
  9  }
 10
 11  if (v.elements.length == 3) {
 12    var r = Matrix.I(4);
 13    r.elements[0][3] = v.elements[0];
 14    r.elements[1][3] = v.elements[1];
 15    r.elements[2][3] = v.elements[2];
 16    return r;
 17  }
 18
 19  throw "Invalid length for Translation";
 20}
 21
 22Matrix.prototype.flatten = function ()
 23{
 24    var result = [];
 25    if (this.elements.length == 0)
 26        return [];
 27
 28
 29    for (var j = 0; j < this.elements[0].length; j++)
 30        for (var i = 0; i < this.elements.length; i++)
 31            result.push(this.elements[i][j]);
 32    return result;
 33}
 34
 35Matrix.prototype.ensure4x4 = function()
 36{
 37    if (this.elements.length == 4 &&
 38        this.elements[0].length == 4)
 39        return this;
 40
 41    if (this.elements.length > 4 ||
 42        this.elements[0].length > 4)
 43        return null;
 44
 45    for (var i = 0; i < this.elements.length; i++) {
 46        for (var j = this.elements[i].length; j < 4; j++) {
 47            if (i == j)
 48                this.elements[i].push(1);
 49            else
 50                this.elements[i].push(0);
 51        }
 52    }
 53
 54    for (var i = this.elements.length; i < 4; i++) {
 55        if (i == 0)
 56            this.elements.push([1, 0, 0, 0]);
 57        else if (i == 1)
 58            this.elements.push([0, 1, 0, 0]);
 59        else if (i == 2)
 60            this.elements.push([0, 0, 1, 0]);
 61        else if (i == 3)
 62            this.elements.push([0, 0, 0, 1]);
 63    }
 64
 65    return this;
 66};
 67
 68Matrix.prototype.make3x3 = function()
 69{
 70    if (this.elements.length != 4 ||
 71        this.elements[0].length != 4)
 72        return null;
 73
 74    return Matrix.create([[this.elements[0][0], this.elements[0][1], this.elements[0][2]],
 75                          [this.elements[1][0], this.elements[1][1], this.elements[1][2]],
 76                          [this.elements[2][0], this.elements[2][1], this.elements[2][2]]]);
 77};
 78
 79Vector.prototype.flatten = function ()
 80{
 81    return this.elements;
 82};
 83
 84function mht(m) {
 85    var s = "";
 86    if (m.length == 16) {
 87        for (var i = 0; i < 4; i++) {
 88            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>";
 89        }
 90    } else if (m.length == 9) {
 91        for (var i = 0; i < 3; i++) {
 92            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>";
 93        }
 94    } else {
 95        return m.toString();
 96    }
 97    return s;
 98}
 99
100//
101// gluLookAt
102//
103function makeLookAt(ex, ey, ez,
104                    cx, cy, cz,
105                    ux, uy, uz)
106{
107    var eye = $V([ex, ey, ez]);
108    var center = $V([cx, cy, cz]);
109    var up = $V([ux, uy, uz]);
110
111    var mag;
112
113    var z = eye.subtract(center).toUnitVector();
114    var x = up.cross(z).toUnitVector();
115    var y = z.cross(x).toUnitVector();
116
117    var m = $M([[x.e(1), x.e(2), x.e(3), 0],
118                [y.e(1), y.e(2), y.e(3), 0],
119                [z.e(1), z.e(2), z.e(3), 0],
120                [0, 0, 0, 1]]);
121
122    var t = $M([[1, 0, 0, -ex],
123                [0, 1, 0, -ey],
124                [0, 0, 1, -ez],
125                [0, 0, 0, 1]]);
126    return m.x(t);
127}
128
129//
130// glOrtho
131//
132function makeOrtho(left, right,
133                   bottom, top,
134                   znear, zfar)
135{
136    var tx = -(right+left)/(right-left);
137    var ty = -(top+bottom)/(top-bottom);
138    var tz = -(zfar+znear)/(zfar-znear);
139
140    return $M([[2/(right-left), 0, 0, tx],
141               [0, 2/(top-bottom), 0, ty],
142               [0, 0, -2/(zfar-znear), tz],
143               [0, 0, 0, 1]]);
144}
145
146//
147// gluPerspective
148//
149function makePerspective(fovy, aspect, znear, zfar)
150{
151    var ymax = znear * Math.tan(fovy * Math.PI / 360.0);
152    var ymin = -ymax;
153    var xmin = ymin * aspect;
154    var xmax = ymax * aspect;
155
156    return makeFrustum(xmin, xmax, ymin, ymax, znear, zfar);
157}
158
159//
160// glFrustum
161//
162function makeFrustum(left, right,
163                     bottom, top,
164                     znear, zfar)
165{
166    var X = 2*znear/(right-left);
167    var Y = 2*znear/(top-bottom);
168    var A = (right+left)/(right-left);
169    var B = (top+bottom)/(top-bottom);
170    var C = -(zfar+znear)/(zfar-znear);
171    var D = -2*zfar*znear/(zfar-znear);
172
173    return $M([[X, 0, A, 0],
174               [0, Y, B, 0],
175               [0, 0, C, D],
176               [0, 0, -1, 0]]);
177}
178
179//
180// glOrtho
181//
182function makeOrtho(left, right, bottom, top, znear, zfar)
183{
184    var tx = - (right + left) / (right - left);
185    var ty = - (top + bottom) / (top - bottom);
186    var tz = - (zfar + znear) / (zfar - znear);
187
188    return $M([[2 / (right - left), 0, 0, tx],
189           [0, 2 / (top - bottom), 0, ty],
190           [0, 0, -2 / (zfar - znear), tz],
191           [0, 0, 0, 1]]);
192}
193