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index.html
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<html>
<head>
<title>Boids in WebGL</title>
<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
<script type="text/javascript" src="gl-matrix.js"></script>
<!-- <script type="text/javascript" src="glMatrix-0.9.5.min.js"></script> -->
<script type="text/javascript" src="webgl-utils.js"></script>
<script id="shader-fs" type="x-shader/x-fragment">
precision mediump float;
varying vec4 vColor;
void main(void) {
gl_FragColor = vColor;
}
</script>
<script id="shader-vs" type="x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec4 aVertexColor;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
varying vec4 vColor;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
vColor = aVertexColor;
}
</script>
<script type="text/javascript">
var gl;
var rTri = 0;
var boids = [];
var lastTime = new Date().getTime();
var minX = -2.5;
var maxX = 4;
var minY = -3.5;
var maxY = 3;
var minZ = -10;
var maxZ = -4;
// TODO: make into sliders
var NUM_BOIDS = 100;
var BOID_UNITS = 100;
var MIN_BOID_DISTANCE = 0.2;
var WIND_ITERATIONS = 30000;
var SCATTER_SIGN = 1;
var WIND_ON = true;
var BOID_VELOCITY_LIMIT = 6;
var BOID_VELOCITY_LIMIT_VEC = vec3.fromValues(BOID_VELOCITY_LIMIT, BOID_VELOCITY_LIMIT, BOID_VELOCITY_LIMIT);
var DEBUG_POSITIONS = false;
// extend vec3 for debugging
vec3.toString = function (v) {
return v[0] + ', ' + v[1] + ', ' + v[2];
};
vec3.divideByScalar = function(out, a, scalar) {
out[0] = a[0] / scalar;
out[1] = a[1] / scalar;
out[2] = a[2] / scalar;
return out;
};
function initGL(canvas) {
try {
gl = canvas.getContext("experimental-webgl");
gl.viewportWidth = canvas.width;
gl.viewportHeight = canvas.height;
} catch (e) {
}
if (!gl) {
alert("Could not initialise WebGL, sorry :-(");
}
}
function getShader(gl, id) {
var shaderScript = document.getElementById(id);
if (!shaderScript) {
return null;
}
var str = "";
var k = shaderScript.firstChild;
while (k) {
if (k.nodeType == 3) {
str += k.textContent;
}
k = k.nextSibling;
}
var shader;
if (shaderScript.type == "x-shader/x-fragment") {
shader = gl.createShader(gl.FRAGMENT_SHADER);
} else if (shaderScript.type == "x-shader/x-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;
}
var shaderProgram;
function initShaders() {
var fragmentShader = getShader(gl, "shader-fs");
var vertexShader = getShader(gl, "shader-vs");
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
alert("Could not initialise shaders");
}
gl.useProgram(shaderProgram);
shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);
shaderProgram.vertexColorAttribute = gl.getAttribLocation(shaderProgram, "aVertexColor");
gl.enableVertexAttribArray(shaderProgram.vertexColorAttribute);
shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
}
var mvMatrix = mat4.create();
var mvMatrixStack = [];
var pMatrix = mat4.create();
function mvPushMatrix() {
mvMatrixStack.push(mat4.clone(mvMatrix));
}
function mvPopMatrix() {
if (mvMatrixStack.length == 0) {
throw "Invalid popMatrix!";
}
mvMatrix = mvMatrixStack.pop();
}
function setMatrixUniforms() {
gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, pMatrix);
gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix);
}
function degToRad(degrees) {
return degrees * Math.PI / 180;
}
var triangleVertexPositionBuffer;
var triangleVertexColorBuffer;
var squareVertexPositionBuffer;
var squareVertexColorBuffer;
function initBuffers() {
triangleVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexPositionBuffer);
var vertices = [
0.0, 1.0, 0.0,
-1.0, -1.0, 0.0,
1.0, -1.0, 0.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
triangleVertexPositionBuffer.itemSize = 3;
triangleVertexPositionBuffer.numItems = 3;
triangleVertexColorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexColorBuffer);
var colors = [
1.0, 0.0, 0.0, 1.0,
0.0, 1.0, 0.0, 1.0,
0.0, 0.0, 1.0, 1.0,
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW);
triangleVertexColorBuffer.itemSize = 4;
triangleVertexColorBuffer.numItems = 3;
squareVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
vertices = [
1.0, 1.0, 0.0,
-1.0, 1.0, 0.0,
1.0, -1.0, 0.0,
-1.0, -1.0, 0.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
squareVertexPositionBuffer.itemSize = 3;
squareVertexPositionBuffer.numItems = 4;
squareVertexColorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexColorBuffer);
colors = []
for (var i=0; i < 4; i++) {
colors = colors.concat([0.5, 0.5, 1.0, 1.0]);
}
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW);
squareVertexColorBuffer.itemSize = 4;
squareVertexColorBuffer.numItems = 4;
}
function randPos(scale) {
scale = scale || 1;
return vec3.random(vec3.create(), scale);
}
function drawScene() {
gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
mat4.perspective(pMatrix, 45, gl.viewportWidth / gl.viewportHeight, 0.1, 100.0);
gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, triangleVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexColorBuffer);
gl.vertexAttribPointer(shaderProgram.vertexColorAttribute, triangleVertexColorBuffer.itemSize, gl.FLOAT, false, 0, 0);
for (var i = 0; i < NUM_BOIDS; i++) {
mat4.identity(mvMatrix);
mat4.translate(mvMatrix, mvMatrix, boids[i].position);
mat4.scale(mvMatrix, mvMatrix, [0.08, 0.08, 0.08]);
mvPushMatrix();
//mat4.rotate(mvMatrix, degToRad(rTri), [0, 1, 0]);
setMatrixUniforms();
gl.drawArrays(gl.TRIANGLES, 0, triangleVertexPositionBuffer.numItems);
mvPopMatrix();
}
}
function animate() {
var timeNow = new Date().getTime();
var v1, v2, v3, boid;
var half = NUM_BOIDS / 2;
if (lastTime != 0) {
var elapsed = timeNow - lastTime;
var dt = elapsed / 1000;
for (var i = 0; i < NUM_BOIDS; i++) {
boid = boids[i]
v1 = rule1(boid, i);
v2 = rule2(boid, i);
v3 = rule3(boid, i);
vec3.multiply(v1, v1, vec3.fromValues(SCATTER_SIGN, SCATTER_SIGN, SCATTER_SIGN));
vec3.add(boid.velocity, boid.velocity, v1);
vec3.add(boid.velocity, boid.velocity, v2);
vec3.add(boid.velocity, boid.velocity, v3);
// try to simulate boids leading a pack
// ideally we would want to only move those on the leading end:w
if (WIND_ON && i < 10) {
vec3.add(boid.velocity, boid.velocity, strong_wind(boid));
}
vec3.add(boid.velocity, boid.velocity, bound_position(boid));
vec3.multiply(boid.velocity, boid.velocity, vec3.fromValues(dt, dt, dt));
limit_velocity(boid);
vec3.add(boids[i].position, boids[i].position, boids[i].velocity);
if (i === 0 && DEBUG_POSITIONS) {
console.log(vec3.toString(boids[0].position));
}
}
rTri += (90 * elapsed) / 1000.0;
}
lastTime = timeNow;
}
function initBoids() {
boids.length = 0;
var r, p = vec3.fromValues(-1.5, 0.0, -7.0);
for (var i = 0; i < NUM_BOIDS; i++) {
// they all start around one point
r = randPos(10);
boids[i] = {position: vec3.add(r, r, p), velocity: vec3.create()};
}
}
// Boids rule 1
// Boids try to fly towards the centre of mass of neighbouring boids
function rule1 (boid, boidIdx) {
// sum of all other boids' positions
var pcj = vec3.create();
for (var i = 0; i < NUM_BOIDS; i++) {
if (boidIdx !== i) {
pcj = vec3.add(pcj, pcj, boids[i].position);
}
}
vec3.divideByScalar(pcj, pcj, NUM_BOIDS - 1);
vec3.subtract(pcj, pcj, boid.position);
return vec3.divideByScalar(pcj, pcj, BOID_UNITS);
}
// Boids rule 2
// Boids try to keep a small distance away from other objects (including other boids).
function rule2 (boid, boidIdx) {
var c = vec3.create();
for (var i = 0; i < NUM_BOIDS; i++) {
if (boidIdx !== i) {
if (vec3.distance(boids[i].position, boid.position) < MIN_BOID_DISTANCE) {
vec3.subtract(c, c, vec3.subtract(vec3.create(), boids[i].position, boid.position));
}
}
}
return c;
}
// Boids rule 3
// Boids try to match velocity with near boids.
function rule3 (boid, boidIdx) {
var pvj = vec3.create();
for (var i = 0; i < NUM_BOIDS; i++) {
if (boidIdx !== i) {
pvj = vec3.add(pvj, pvj, boids[i].velocity);
}
}
vec3.divideByScalar(pvj, pvj, NUM_BOIDS - 1);
vec3.subtract(pvj, pvj, boid.velocity);
return vec3.divideByScalar(pvj, pvj, VELOCITY_DIVISOR);
}
var winds = 0;
var lastWind;
function strong_wind (boid) {
if (!lastWind) {
lastWind = randPos(0.5);
}
else if (winds++ > WIND_ITERATIONS) {
lastWind = randPos(0.3);
winds = 0;
document.querySelector('#winddir').innerText = 'Wind direction: ' + vec3.toString(lastWind);
}
return lastWind;
}
function bound_position (boid) {
var v = vec3.create();
if (boid.position[0] > maxX) {
v[0] = -10;
}
else if (boid.position[0] < minX) {
v[0] = 10;
}
if (boid.position[1] > maxY) {
v[1] = -10;
}
else if (boid.position[1] < minY) {
v[1] = 10;
}
if (boid.position[2] > maxZ) {
v[2] = -10;
}
else if (boid.position[2] < minZ) {
v[2] = 10;
}
return v;
}
// apply velocity speed limit to a boid
function limit_velocity (boid) {
var v = vec3.create();
if (vec3.length(boid.velocity) > BOID_VELOCITY_LIMIT) {
vec3.divide(boid.velocity, boid.velocity, vec3.length(boid.velocity));
vec3.multiply(boid.velocity, boid.velocity, BOID_VELOCITY_LIMIT_VEC);
}
}
function scatter() {
SCATTER_SIGN = -1;
setTimeout(function () {
SCATTER_SIGN = 1;
}, 3000);
}
function updateParams() {
var nboids = parseInt(document.querySelector('#boids').value, 10);
MIN_BOID_DISTANCE = parseFloat(document.querySelector('#mindist').value, 10);
BOID_UNITS = parseInt(document.querySelector('#units').value, 10);
VELOCITY_DIVISOR = parseInt(document.querySelector('#rule3div').value, 10);
WIND_ON = document.querySelector('#wind').checked;
document.querySelector('#boidsv').innerText = nboids;
document.querySelector('#mindistv').innerText = MIN_BOID_DISTANCE;
document.querySelector('#unitsv').innerText = BOID_UNITS;
document.querySelector('#velv').innerText = VELOCITY_DIVISOR;
if (nboids !== NUM_BOIDS) {
NUM_BOIDS = nboids;
initBoids();
}
}
function tick() {
requestAnimFrame(tick);
drawScene();
animate();
}
function webGLStart() {
var canvas = document.getElementById("lesson03-canvas");
initGL(canvas);
initShaders()
initBuffers();
updateParams();
initBoids();
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.enable(gl.DEPTH_TEST);
tick();
}
</script>
</head>
<body onload="webGLStart();">
<div>
<canvas id="lesson03-canvas" style="border: none;" width="800" height="800"></canvas>
</div>
<span id="winddir"></span><br/>
<label for="boids">Boids count</label>
<input id=boids type=range min=10 max=1000 step=10 value=100 onchange="updateParams(value)"><span id=boidsv></span><br>
<label for="min dist">Min distance</label>
<input id=mindist type=range min=0.01 max=1 step=0.05 value=0.2 onchange="updateParams(value)"><span id=mindistv></span><br>
<label for="boid units">Boid units</label>
<input id=units type=range min=1 max=10 step=1 value=10 onchange="updateParams(value)"><span id=unitsv></span><br>
<label for="velocity div">Velocity divisor</label>
<input id=rule3div type=range min=1 max=100 step=1 value=8 onchange="updateParams(value)"><span id=velv></span><br>
<input id=wind type="checkbox" checked onchange="updateParams()"> Wind<br>
<input type="button" value="Scatter" onclick="scatter()"/>
</body>
</html>