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Copy pathAnti-Aliasing Test Jitter.html
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Anti-Aliasing Test Jitter.html
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<html>
<head>
<title>Raytracing Coffee</title>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<style>
td {
width: 4px;
height: 4px;
}
</style>
</head>
<body>
<table cellspacing="0" cellpadding="0"></table>
</body>
<script type="text/coffeescript">
len = (u) ->
Math.sqrt(dot(u, u))
dot = (u, v) ->
v[0] * u[0] + v[1] * u[1] + v[2] * u[2]
sub = (u, v) ->
[u[0] - v[0], u[1] - v[1], u[2] - v[2]]
add = (u, v) ->
[v[0] + u[0], v[1] + u[1], v[2] + u[2]]
mul = (s, v) ->
[s * v[0], s * v[1], s * v[2]]
normalize = (v) ->
length = Math.sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2])
[v[0] / length, v[1] / length, v[2] / length]
scale = (s, v) ->
[s * v[0], s * v[1], s * v[2]]
class Sphere
constructor: (@center, @radius) ->
intersect: (g, d) ->
# g is the ray origin
# d is the ray direction
c = sub(@center, g)
s = dot(c, d)
discr = (@radius * @radius) - dot(c, c) + s*s
console.log(g, d, c, s, discr) if debug
if discr < 0
return Infinity
return s - Math.sqrt(discr)
normal: (poi) ->
normalize(sub(poi, @center))
class Plane
constructor: (@n, @d) -> #n is the normal vector
@n = normalize(@n)
intersect: (g, d) ->
#@d is referring to the distance from the origin
# distance to the point of intersection on the plane
(dot(g, @n) + @d) / dot(d, @n)
normal: (poi) ->
@n
light = [100, 100, -100]
shapes = []
shapes.push new Plane [0, 1, 0], -1.2
shapes.push new Sphere [0, 0, 5], 1
# g is the origin of the ray (can be the poi or the eye)
# d is the direction
findNearestObject = (g, d) ->
near = t: Infinity
for shape in shapes
# t is the distance to shape
t = shape.intersect(g, d)
#console.log t, eye, dir
if t > 1e-7 && t < near.t
near.t = t
near.shape = shape
near
# What color is pixel x,y?
pixel = (x, y) ->
eye = [0, 0, 0]
dir = normalize([x, y, 3]) #controls field of view
#scale(255, dir)
near = findNearestObject(eye, dir)
if near.t < Infinity
# poi = eye + near.t * dir
poi = add(eye, mul(near.t, dir))
#computes the normal vector for the closest shape given a point of intersection
n = near.shape.normal(poi)
#computes the vector from the point of intersection to the light
# we normalize the light because we want to think of the light infinitely back
l = normalize(sub(light, poi))
shadow = findNearestObject(poi, l)
bright = 0
if shadow.t == Infinity
# dot product gives us the brightness
bright = dot(l, n)
console.log(dir, near, l, n, bright) if debug
# if we hit something with a ray then we return a color
return [255 * bright, 0, 0]
return [0, 0, 255]
r = 2
w = 80 # w is the resolution
n = 1 # n is the number of rays shot through each pixel
debug = false
if debug
console.log pixel 1, .4
else
for v in [-w...w]
tr = "<tr>"
for u in [-w...w]
accum = [0, 0, 0] #The initial value of the accumulator before averaging all the rays
for k in [1..n]
randX = (Math.random() * 2) - 1
randY = (Math.random() * 2) - 1
color = pixel((u / w) + randX / 10, -(v / w) + randY / 10)
accum = add(accum, color)
averageColor = mul(1.0 / n, accum)
tr += '<td style = "background:rgb('+Math.floor(averageColor[0]) + ',' + Math.floor(averageColor[1]) + ',' + Math.floor(averageColor[2]) + ')"></td>'
tr += "</tr>"
jQuery('table').append(tr)
</script>
<!-- Coffeescript compiling link -->
<script src="https://cdn.rawgit.com/jashkenas/coffeescript/1.11.1/extras/coffee-script.js"></script>
</html>