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// app.js
var initDemo = function() {
console.log("Init demo called");
var canvas = document.getElementById("game-surface");
var gl = canvas.getContext("webgl");
if (!gl) {
console.log("Need to use experimental WebGL");
gl = canvas.getContext("experimental-webgl");
}
if (!gl) {
alert("Your browser does not support WebGL.");
}
// Scale the canvas to the size of the window
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
gl.viewport(0, 0, window.innerWidth, window.innerHeight);
// Initialise WebGL
gl.clearColor(.75, .85, .8, 1.0);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
gl.enable(gl.DEPTH_TEST);
gl.enable(gl.CULL_FACE);
gl.frontFace(gl.CCW);
gl.cullFace(gl.BACK);
// Create shaders
var vertexShader = gl.createShader(gl.VERTEX_SHADER);
var fragmentShader = gl.createShader(gl.FRAGMENT_SHADER);
gl.shaderSource(vertexShader, vertexShaderText);
gl.shaderSource(fragmentShader, fragmentShaderText);
gl.compileShader(vertexShader);
if (!gl.getShaderParameter(vertexShader, gl.COMPILE_STATUS)) {
console.error("ERROR compiling vertex shader:", gl.getShaderInfoLog(vertexShader));
return;
}
gl.compileShader(fragmentShader);
if (!gl.getShaderParameter(fragmentShader, gl.COMPILE_STATUS)) {
console.error("ERROR compiling fragment shader:", gl.getShaderInfoLog(fragmentShader));
return;
}
var program = gl.createProgram();
gl.attachShader(program, vertexShader);
gl.attachShader(program, fragmentShader);
gl.linkProgram(program);
if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
console.error("ERROR linking program:", gl.getProgramInfoLog(program));
return;
}
gl.validateProgram(program);
if (!gl.getProgramParameter(program, gl.VALIDATE_STATUS)) {
console.error("ERROR validating program:", gl.getProgramInfoLog(program));
return;
}
var cubeVertices = [
// X Y Z U V
// Top
-1.0, 1.0, -1.0, 0, 0,
-1.0, 1.0, 1.0, 0, 1,
1.0, 1.0, 1.0, 1, 1,
1.0, 1.0, -1.0, 1, 0,
// Left
-1.0, 1.0, 1.0, 0, 0,
-1.0, -1.0, 1.0, 1, 0,
-1.0, -1.0, -1.0, 1, 1,
-1.0, 1.0, -1.0, 0, 1,
// Right
1.0, 1.0, 1.0, 1, 1,
1.0, -1.0, 1.0, 0, 1,
1.0, -1.0, -1.0, 0, 0,
1.0, 1.0, -1.0, 1, 0,
// Front
1.0, 1.0, 1.0, 1, 1,
1.0, -1.0, 1.0, 1, 0,
-1.0, -1.0, 1.0, 0, 0,
-1.0, 1.0, 1.0, 0, 1,
// Back
1.0, 1.0, -1.0, 0, 0,
1.0, -1.0, -1.0, 0, 1,
-1.0, -1.0, -1.0, 1, 1,
-1.0, 1.0, -1.0, 1, 0,
// Bottom
-1.0, -1.0, -1.0, 1, 1,
-1.0, -1.0, 1.0, 1, 0,
1.0, -1.0, 1.0, 0, 0,
1.0, -1.0, -1.0, 0, 1,
]
var cubeIndices = [
// Top
0, 1, 2,
0, 2, 3,
// Left
5, 4, 6,
6, 4, 7,
// Right
8, 9, 10,
8, 10, 11,
// Front
13, 12, 14,
15, 14, 12,
// Back
16, 17, 18,
16, 18, 19,
// Bottom
21, 20, 22,
22, 20, 23
]
var cubeVertexBufferObject = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexBufferObject);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(cubeVertices), gl.STATIC_DRAW);
var cubeIndexBufferObject = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeIndexBufferObject);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(cubeIndices), gl.STATIC_DRAW);
var positionAttributeLocation = gl.getAttribLocation(program, "vertPosition");
gl.vertexAttribPointer(
positionAttributeLocation, // Attribute location
3, // Number of elements per attribute
gl.FLOAT, // Type of elements
gl.FALSE, // Some OpenGL thing
5 * Float32Array.BYTES_PER_ELEMENT, // Size of an individual vertex
0 // Offset from the beginning of a single vertex to this attribute
);
var texCoordAttributeLocation = gl.getAttribLocation(program, "vertTexCoord");
gl.vertexAttribPointer(
texCoordAttributeLocation, // Attribute location
2, // Number of elements per attribute,
gl.FLOAT, // Type of elements
gl.FALSE, // Some OpenGL thing
5 * Float32Array.BYTES_PER_ELEMENT, // Size of an individual vertex
3 * Float32Array.BYTES_PER_ELEMENT // Offset from the beginning of a single vertex to this attribute
);
gl.enableVertexAttribArray(positionAttributeLocation);
gl.enableVertexAttribArray(texCoordAttributeLocation);
// Create texture
var cubeTexture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, cubeTexture);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
textureElem = document.getElementById("grunge-01");
gl.texImage2D(
gl.TEXTURE_2D,
0,
gl.RGBA,
gl.RGBA,
gl.UNSIGNED_BYTE,
textureElem);
gl.bindTexture(gl.TEXTURE_2D, null);
// Tell OpenGL state machine which program should be active
gl.useProgram(program);
var matWorldUniformLocation = gl.getUniformLocation(program, "mWorld");
var matViewUniformLocation = gl.getUniformLocation(program, "mView");
var matProjUniformLocation = gl.getUniformLocation(program, "mProj");
var worldMatrix = new Float32Array(16);
var viewMatrix = new Float32Array(16);
var projMatrix = new Float32Array(16);
mat4.identity(worldMatrix);
mat4.lookAt(viewMatrix, [0, 0, -4], [0, 0, 0], [0, 1, 0]);
verticalFOV = 60;
mat4.perspective(projMatrix, glMatrix.toRadian(verticalFOV), canvas.width / canvas.height, 0.1, 1000.0);
gl.uniformMatrix4fv(matWorldUniformLocation, gl.FALSE, worldMatrix);
gl.uniformMatrix4fv(matViewUniformLocation, gl.FALSE, viewMatrix);
gl.uniformMatrix4fv(matProjUniformLocation, gl.FALSE, projMatrix);
var xRotationMatrix = new Float32Array(16);
var yRotationMatrix = new Float32Array(16);
// Main render loop
var identityMatrix = new Float32Array(16);
mat4.identity(identityMatrix);
var angle = 0;
var loop = function() {
// One full rotation every six seconds
angle = performance.now() / 1000 / 6 * 2 * Math.PI;
// Set the cube spinning on the X and Y axes
mat4.rotate(yRotationMatrix, identityMatrix, angle, [0, 1, 0]);
mat4.rotate(xRotationMatrix, identityMatrix, angle / 4, [1, 0, 0]);
mat4.mul(worldMatrix, yRotationMatrix, xRotationMatrix);
gl.uniformMatrix4fv(matWorldUniformLocation, gl.FALSE, worldMatrix);
gl.clearColor(.75, .85, .8, 1.0);
gl.clear(gl.DEPTH_BUFFER_BIT | gl.COLOR_BUFFER_BIT);
gl.bindTexture(gl.TEXTURE_2D, cubeTexture);
gl.activeTexture(gl.TEXTURE0);
gl.drawElements(gl.TRIANGLES, cubeIndices.length, gl.UNSIGNED_SHORT, 0);
requestAnimationFrame(loop);
}
requestAnimationFrame(loop);
};