Created
September 17, 2012 10:37
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Simple blods algorithm used to make strange generative patters. By Tim Holman
@twholman
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<canvas id='c'></canvas> |
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var width = window.innerWidth - 8, height = window.innerHeight - 8, timerID = 0, c2 = document.getElementById('c'), ctx = c2.getContext('2d'); | |
ctx.globalCompositeOperation = 'source-over'; | |
c2.width = width; | |
c2.height = height; | |
var speed = 10; | |
var size = 1; | |
var boids = []; | |
var points = new Array(); | |
var totalBoids = 7; | |
var pointCount = 0; | |
var init = function(){ | |
for (var i = 0; i < totalBoids; i++) { | |
boids.push({ | |
x: Math.random() * width, | |
y: Math.random() * height, | |
v: { | |
x: Math.random() * 2 - 1, | |
y: Math.random() * 2 - 1 | |
} | |
}); | |
} | |
setInterval(update, 40); | |
} | |
var calculateDistance = function(v1, v2){ | |
x = Math.abs(v1.x - v2.x); | |
y = Math.abs(v1.y - v2.y); | |
return Math.sqrt((x * x) + (y * y)); | |
} | |
var checkWallCollisions = function(index){ | |
if (boids[index].x > width) { | |
boids[index].x = 0; | |
} | |
else | |
if (boids[index].x < 0) { | |
boids[index].x = width; | |
} | |
if (boids[index].y > height) { | |
boids[index].y = 0; | |
} | |
else | |
if (boids[index].y < 0) { | |
boids[index].y = height; | |
} | |
} | |
var addForce = function(index, force){ | |
boids[index].v.x += force.x; | |
boids[index].v.y += force.y; | |
magnitude = calculateDistance({ | |
x: 0, | |
y: 0 | |
}, { | |
x: boids[index].v.x, | |
y: boids[index].v.y | |
}); | |
boids[index].v.x = boids[index].v.x / magnitude; | |
boids[index].v.y = boids[index].v.y / magnitude; | |
} | |
//This should be in multiple functions, but this will | |
//save tons of looping - Gross! | |
var applyForces = function(index){ | |
percievedCenter = { | |
x: 0, | |
y: 0 | |
}; | |
flockCenter = { | |
x: 0, | |
y: 0 | |
}; | |
percievedVelocity = { | |
x: 0, | |
y: 0 | |
}; | |
count = 0; | |
for (var i = 0; i < boids.length; i++) { | |
if (i != index) { | |
//Allignment | |
dist = calculateDistance(boids[index], boids[i]); | |
//console.log(dist); | |
if (dist > 0 && dist < 50) { | |
count++; | |
//Alignment | |
percievedCenter.x += boids[i].x; | |
percievedCenter.y += boids[i].y; | |
//Cohesion | |
percievedVelocity.x += boids[i].v.x; | |
percievedVelocity.y += boids[i].v.y; | |
//Seperation | |
if (calculateDistance(boids[i], boids[index]) < 10) { | |
flockCenter.x -= (boids[i].x - boids[index].x); | |
flockCenter.y -= (boids[i].y - boids[index].y); | |
} | |
} | |
} | |
} | |
if (count > 0) { | |
percievedCenter.x = percievedCenter.x / count; | |
percievedCenter.y = percievedCenter.y / count; | |
percievedCenter.x = (percievedCenter.x - boids[index].x) / 400; | |
percievedCenter.y = (percievedCenter.y - boids[index].y) / 400; | |
percievedVelocity.x = percievedVelocity.x / count; | |
percievedVelocity.y = percievedVelocity.y / count; | |
flockCenter.x /= count; | |
flockCenter.y /= count; | |
} | |
addForce(index, percievedCenter); | |
addForce(index, percievedVelocity); | |
addForce(index, flockCenter); | |
} | |
var update = function(){ | |
for (var i = 0; i < boids.length; i++) { | |
var d, dx, dy,j; | |
//Draw boid | |
ctx.strokeStyle = "rgba(0, 0 , 0, 0.5)"; | |
ctx.lineWidth = size; | |
ctx.beginPath(); | |
ctx.moveTo(boids[i].x, boids[i].y); | |
boids[i].x += boids[i].v.x * speed; | |
boids[i].y += boids[i].v.y * speed; | |
applyForces(i); | |
ctx.lineTo(boids[i].x, boids[i].y); | |
ctx.stroke(); | |
points.push( [ boids[i].x, boids[i].y ] ); | |
//Web | |
ctx.strokeStyle = "rgba(0, 0 , 0, 0.1)"; | |
for (j = 0; j < points.length; j++) | |
{ | |
dx = points[j][0] - points[pointCount][0]; | |
dy = points[j][1] - points[pointCount][1]; | |
d = dx * dx + dy * dy; | |
if (d < 2500 && Math.random() > 0.9) | |
{ | |
ctx.beginPath(); | |
ctx.moveTo( points[pointCount][0], points[pointCount][1]); | |
ctx.lineTo( points[j][0], points[j][1]); | |
ctx.stroke(); | |
} | |
} | |
pointCount++; | |
checkWallCollisions(i); | |
} | |
} | |
//Gui uses this to clear the canvas | |
var clearCanvas = function(){ | |
ctx.fillStyle = 'rgba(255, 255, 255, 1.0)'; | |
ctx.beginPath(); | |
ctx.rect(0, 0, width, height); | |
ctx.closePath(); | |
ctx.fill(); | |
} | |
init(); |
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