cube.html
7.96 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
<html>
<head>
<title>First very simple WebGL example...</title>
<script src="./gl-matrix-min.js" type="text/javascript"></script>
<script type="text/javascript">
var projectionMatrix, modelViewMatrix;
var rotationAxis;
var shaderProgram, shaderVertexPositionAttribute
var shaderVertexColorAttribute;
var shaderProjectionMatrixUniform, shaderModelViewMatrixUniform;
var duration = 5000; // ms
var currentTime = Date.now();
function initWebGL(canvas) {
var gl = null;
var msg = "Your browser does not support WebGL, " +
"or it is not enabled by default.";
try {
gl = canvas.getContext("experimental-webgl");
}
catch (e) {
msg = "Error creating WebGL Context!: " + e.toString();
}
if (!gl) {
alert(msg);
throw new Error(msg);
}
return gl;
}
function initViewport(gl, canvas) {
gl.viewport(0, 0, canvas.width, canvas.height);
}
// Create the vertex, color, and index data for a
// multicolored cube
function createCube(gl) {
// Vertex Data
var vertexBuffer;
vertexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
var verts = [
// Front face
-1.0, -1.0, 1.0,
1.0, -1.0, 1.0,
1.0, 1.0, 1.0,
-1.0, 1.0, 1.0,
// Back face
-1.0, -1.0, -1.0,
-1.0, 1.0, -1.0,
1.0, 1.0, -1.0,
1.0, -1.0, -1.0,
// Top face
-1.0, 1.0, -1.0,
-1.0, 1.0, 1.0,
1.0, 1.0, 1.0,
1.0, 1.0, -1.0,
// Bottom face
-1.0, -1.0, -1.0,
1.0, -1.0, -1.0,
1.0, -1.0, 1.0,
-1.0, -1.0, 1.0,
// Right face
1.0, -1.0, -1.0,
1.0, 1.0, -1.0,
1.0, 1.0, 1.0,
1.0, -1.0, 1.0,
// Left face
-1.0, -1.0, -1.0,
-1.0, -1.0, 1.0,
-1.0, 1.0, 1.0,
-1.0, 1.0, -1.0
];
gl.bufferData(
gl.ARRAY_BUFFER,
new Float32Array(verts),
gl.STATIC_DRAW);
// Color data
var colorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, colorBuffer);
var faceColors = [
[1.0, 0.0, 0.0, 1.0], // Front face
[0.0, 1.0, 0.0, 1.0], // Back face
[0.0, 0.0, 1.0, 1.0], // Top face
[1.0, 1.0, 0.0, 1.0], // Bottom face
[1.0, 0.0, 1.0, 1.0], // Right face
[0.0, 1.0, 1.0, 1.0] // Left face
];
var vertexColors = [];
for (var i in faceColors) {
var color = faceColors[i];
for (var j=0; j < 4; j++) {
vertexColors = vertexColors.concat(color);
}
}
gl.bufferData(
gl.ARRAY_BUFFER,
new Float32Array(vertexColors),
gl.STATIC_DRAW);
// Index data (defines the triangles to be drawn)
var cubeIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeIndexBuffer);
var cubeIndices = [
0, 1, 2, 0, 2, 3, // Front face
4, 5, 6, 4, 6, 7, // Back face
8, 9, 10, 8, 10, 11, // Top face
12, 13, 14, 12, 14, 15, // Bottom face
16, 17, 18, 16, 18, 19, // Right face
20, 21, 22, 20, 22, 23 // Left face
];
gl.bufferData(
gl.ELEMENT_ARRAY_BUFFER,
new Uint16Array(cubeIndices),
gl.STATIC_DRAW);
var cube = {
buffer:vertexBuffer,
colorBuffer:colorBuffer,
indices:cubeIndexBuffer,
vertSize:3,
nVerts:24,
colorSize:4,
nColors: 24,
nIndices:36,
primtype:gl.TRIANGLES};
return cube;
}
function initMatrices(canvas) {
modelViewMatrix = mat4.create();
mat4.translate(
modelViewMatrix, modelViewMatrix, [0, 0, -8]);
// Create a project matrix with 45 degree field of view
projectionMatrix = mat4.create();
mat4.perspective(projectionMatrix, Math.PI / 4,
canvas.width / canvas.height, 1, 10000);
rotationAxis = vec3.create();
vec3.normalize(rotationAxis, [1, 1, 1]);
}
function createShader(gl, id, type) {
var shader;
var str = document.getElementById(id).text;
if (type == "fragment") {
shader = gl.createShader(gl.FRAGMENT_SHADER);
} else if (type == "vertex") {
shader = gl.createShader(gl.VERTEX_SHADER);
} else {
return null;
}
gl.shaderSource(shader, str);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
alert(gl.getShaderInfoLog(shader));
return null;
}
return shader;
}
function initShader(gl, vertex, fragment) {
// load and compile the fragment and vertex shader
var fragmentShader = createShader(gl, fragment, "fragment");
var vertexShader = createShader(gl, vertex, "vertex");
// link them together into a new program
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
// get pointers to the shader params
shaderVertexPositionAttribute = gl.getAttribLocation(
shaderProgram, "vertexPos");
gl.enableVertexAttribArray(shaderVertexPositionAttribute);
shaderVertexColorAttribute = gl.getAttribLocation(
shaderProgram, "vertexColor");
gl.enableVertexAttribArray(shaderVertexColorAttribute);
shaderProjectionMatrixUniform = gl.getUniformLocation(
shaderProgram, "projectionMatrix");
shaderModelViewMatrixUniform = gl.getUniformLocation(
shaderProgram, "modelViewMatrix");
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
alert("Could not initialise shaders");
}
}
function draw(gl, obj) {
// clear the background (transparent)
gl.clearColor(0.0, 0.0, 0.0, 0.0);
// // clear the background (black)
// gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.enable(gl.DEPTH_TEST);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// set the shader to use
gl.useProgram(shaderProgram);
// connect up the shader parameters: vertex position,
// color, and projection/model matrices
// set up the buffers
gl.bindBuffer(gl.ARRAY_BUFFER, obj.buffer);
gl.vertexAttribPointer(shaderVertexPositionAttribute,
obj.vertSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, obj.colorBuffer);
gl.vertexAttribPointer(shaderVertexColorAttribute,
obj.colorSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, obj.indices);
gl.uniformMatrix4fv(shaderProjectionMatrixUniform, false,
projectionMatrix);
gl.uniformMatrix4fv(shaderModelViewMatrixUniform, false,
modelViewMatrix);
// draw the object
gl.drawElements(
obj.primtype, obj.nIndices, gl.UNSIGNED_SHORT, 0);
}
function animate() {
var now = Date.now();
var deltat = now - currentTime;
currentTime = now;
var fract = deltat / duration;
var angle = Math.PI * 2 * fract;
mat4.rotate(
modelViewMatrix, modelViewMatrix, angle, rotationAxis);
}
function run(gl, cube) {
requestAnimationFrame(function() { run(gl, cube); });
draw(gl, cube);
animate();
}
function startGl() {
// Get A WebGL context
var canvas = document.getElementById("cube");
var gl = initWebGL(canvas);
var obj = createCube(gl);
initViewport(gl, canvas);
initMatrices(canvas);
initShader(
gl,
"cube-vertex-shader",
"cube-fragment-shader");
run(gl, obj);
}
</script>
<script id="cube-vertex-shader" type="x-shader/x-vertex">
attribute vec3 vertexPos;
attribute vec4 vertexColor;
uniform mat4 modelViewMatrix;
uniform mat4 projectionMatrix;
varying vec4 vColor;
void main(void) {
// Return the transformed and projected vertex value
gl_Position =
projectionMatrix * modelViewMatrix * vec4(vertexPos, 1.0);
// Output the vertexColor in vColor
vColor = vertexColor;
}
</script>
<script id="cube-fragment-shader" type="x-shader/x-fragment">
precision mediump float;
varying vec4 vColor;
void main(void) {
// Return the pixel color: always output white
gl_FragColor = vColor;
}
</script>
</head>
<body onLoad="startGl()">
<canvas id="cube" width="200" height="200"></canvas>
</body>
</html>
<!-- vim: set ts=4 sw=4: -->