-
Notifications
You must be signed in to change notification settings - Fork 2
/
image_atlas.html
264 lines (215 loc) · 7.54 KB
/
image_atlas.html
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
<!-- vim: sw=4 ts=4 expandtab smartindent ft=javascript
-->
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title>WebGL Demo</title>
<style> document, body { margin: 0px; padding: 0px; overflow: hidden; } </style>
</head>
<body>
<canvas id="glcanvas"></canvas>
<script>
const canvas = document.getElementById('glcanvas');
const gl = canvas.getContext('webgl2', {antialias: true});
if (!gl) { alert('Failed to initialize WebGL'); }
(window.onresize = () => {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
/* account for e.g. high-retina macbook screens */
if (window.devicePixelRatio > 1) {
canvas.style.width = `${canvas.width}px`;
canvas.style.height = `${canvas.height}px`;
canvas.width *= window.devicePixelRatio;
canvas.height *= window.devicePixelRatio;
}
gl.viewport(
0,
0,
canvas.width,
canvas.height
);
})();
const geo_vbuf_pos = gl.createBuffer();
const geo_vbuf_uv = gl.createBuffer();
const geo_ibuf = gl.createBuffer();
let shaders;
/* compile shaders */
{
const vs_geo = `
attribute vec3 a_pos;
attribute vec2 a_uv;
varying vec2 v_uv;
void main() {
gl_Position = vec4(a_pos.xyz, 1);
v_uv = a_uv;
}`;
const fs_geo = `
precision mediump float;
uniform sampler2D u_texture;
varying vec2 v_uv;
void main() {
gl_FragColor = texture2D(u_texture, v_uv);
}`;
function createProgram(gl, vertexSource, fragmentSource) {
function createShader(gl, type, source) {
const shader = gl.createShader(type);
gl.shaderSource(shader, source);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
throw new Error(gl.getShaderInfoLog(shader));
}
return shader;
}
const program = gl.createProgram();
const vertexShader = createShader(gl, gl.VERTEX_SHADER, vertexSource);
const fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, fragmentSource);
gl.attachShader(program, vertexShader);
gl.attachShader(program, fragmentShader);
gl.linkProgram(program);
if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
throw new Error(gl.getProgramInfoLog(program));
}
const wrapper = {program};
const numAttributes = gl.getProgramParameter(program, gl.ACTIVE_ATTRIBUTES);
for (let i = 0; i < numAttributes; i++) {
const attribute = gl.getActiveAttrib(program, i);
wrapper[attribute.name] = gl.getAttribLocation(program, attribute.name);
}
const numUniforms = gl.getProgramParameter(program, gl.ACTIVE_UNIFORMS);
for (let i = 0; i < numUniforms; i++) {
const uniform = gl.getActiveUniform(program, i);
wrapper[uniform.name] = gl.getUniformLocation(program, uniform.name);
}
return wrapper;
}
shaders = {
geo: createProgram(gl, vs_geo, fs_geo)
}
}
let atlas = gl.createTexture();
const ATLAS_SIZE = 2; /* in emoji */
const EMOJI_SIZE = 256;
{
const canvas = document.createElement("canvas");
canvas.width = canvas.height = ATLAS_SIZE * EMOJI_SIZE;
const ctx = canvas.getContext("2d");
{
const atlas = ['⭐️', '💫', '✨', '🪐'];
const PAD = EMOJI_SIZE*0.2;
ctx.font = (EMOJI_SIZE - PAD*2) + 'px sans-serif';
let i = 0;
for (const char of atlas) {
const x = ( i % ATLAS_SIZE ) * EMOJI_SIZE;
const y = (Math.floor(i / ATLAS_SIZE)) * EMOJI_SIZE;
ctx.fillText(
char,
x + PAD,
y + EMOJI_SIZE - PAD
);
i++;
}
}
gl.bindTexture(gl.TEXTURE_2D, atlas);
gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, true);
gl.texImage2D(
/* target */ gl.TEXTURE_2D,
/* level */ 0,
/* internalformat */ gl.RGBA,
/* width */ canvas.width,
/* height */ canvas.height,
/* border, */ 0,
/* format, */ gl.RGBA,
/* type, */ gl.UNSIGNED_BYTE,
/* data */ canvas
);
gl.generateMipmap(gl.TEXTURE_2D);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_LINEAR);
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);
}
const geo = {
idx: [],
pos: [],
uv : [],
};
{
function drawBox(x, y, size, atlas_index) {
/* generate UVs from atlas_index */
{
const u = ( atlas_index % ATLAS_SIZE );
const v = (Math.floor(atlas_index / ATLAS_SIZE));
geo.uv.push(
(u+1)/ATLAS_SIZE, (v+1)/ATLAS_SIZE,
(u+0)/ATLAS_SIZE, (v+1)/ATLAS_SIZE,
(u+0)/ATLAS_SIZE, (v+0)/ATLAS_SIZE,
(u+1)/ATLAS_SIZE, (v+0)/ATLAS_SIZE
);
}
/* generate position + index */
{
const vbuf_i = geo.pos.length / 3;
const ar = window.innerWidth / window.innerHeight;
geo.pos.push(x+size, y-size*ar, 0.1);
geo.pos.push(x-size, y-size*ar, 0.1);
geo.pos.push(x-size, y+size*ar, 0.1);
geo.pos.push(x+size, y+size*ar, 0.1);
geo.idx.push(
vbuf_i + 0,
vbuf_i + 1,
vbuf_i + 2,
vbuf_i + 2,
vbuf_i + 3,
vbuf_i + 0
);
}
}
for (let x = -1; x <= 1; x += 0.1) {
for (let y = -1; y <= 1; y += 0.1) {
drawBox(
x + (0.5 - Math.random())*0.1,
y + (0.5 - Math.random())*0.1,
0.005 + Math.random()*0.01,
~~(Math.random()*4)
);
}
}
}
requestAnimationFrame(function frame(timestamp) {
requestAnimationFrame(frame);
{
/* set up premultiplied alpha */
gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
gl.enable(gl.BLEND);
/* clear all */
gl.clearColor(1, 1, 1, 1);
gl.clear(gl.COLOR_BUFFER_BIT);
/* geo pass */
{
gl.useProgram(shaders.geo.program);
gl.enableVertexAttribArray(shaders.geo.a_pos);
gl.enableVertexAttribArray(shaders.geo.a_uv);
/* upload/bind atlas */
{
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, atlas);
gl.uniform1i(shaders.geo.u_texture, 0);
}
/* upload/bind geometry */
{
gl.bindBuffer(gl.ARRAY_BUFFER, geo_vbuf_pos);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(geo.pos), gl.STATIC_DRAW);
gl.vertexAttribPointer(shaders.geo.a_pos, 3, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, geo_vbuf_uv);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(geo.uv), gl.STATIC_DRAW);
gl.vertexAttribPointer(shaders.geo.a_uv, 2, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, geo_ibuf);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(geo.idx), gl.STATIC_DRAW);
}
gl.drawElements(gl.TRIANGLES, geo.idx.length, gl.UNSIGNED_SHORT, 0);
}
}
})
</script>
</body>
</html>