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Merge pull request #2 from AtelierArith/enjoy-with-minifb
add demoscript
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# -*- coding: utf-8 -*- | ||
using LinearAlgebra | ||
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using Plots | ||
using Distributions | ||
using MiniFB | ||
using Plots | ||
using FileIO | ||
using ImageTransformations | ||
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using GeometryObjects | ||
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const WIDTH = 600 | ||
const HEIGHT = 600 | ||
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function populate_buffer!(buffer, img) | ||
global WIDTH, HEIGHT | ||
buffer .= zero(UInt32) | ||
h, w = size(img) | ||
ratio = min(1, HEIGHT/h, WIDTH/w) | ||
nimg = imresize(img, ratio=ratio) | ||
nh, nw = size(nimg) | ||
oh = (HEIGHT-nh) ÷ 2 | ||
ow = (WIDTH-nw) ÷ 2 | ||
for i in 1:nh | ||
for j in 1:nw | ||
buffer[(oh+i-1)*WIDTH + ow+j] = mfb_rgb(nimg[i,j]) | ||
end | ||
end | ||
end | ||
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Base.@kwdef struct CollisionSystem | ||
xmin::Float64 = -4 | ||
xmax::Float64 = 4 | ||
ymin::Float64 = -4 | ||
ymax::Float64 = 4 | ||
maxT::Int = 500 | ||
num_particles::Int = 20 | ||
end | ||
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function setup_particle(sys::CollisionSystem) | ||
particles = Particle2D[] | ||
num_particles = sys.num_particles | ||
while length(particles) != num_particles | ||
θ = 2π * rand() | ||
v_abs = 0.1 | ||
v = Velocity2D(v_abs * cos(θ), v_abs * sin(θ)) | ||
m = r = rand(Uniform(0.1, 0.3)) | ||
x = rand(Uniform(sys.xmin + r, sys.xmax - r)) | ||
y = rand(Uniform(sys.ymin + r, sys.ymax - r)) | ||
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c = Particle2D( | ||
Circle2D(Point2D(x, y), r), | ||
v, | ||
m, | ||
) | ||
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c_plus_r = Particle2D( | ||
Circle2D(Point2D(x, y), r + v_abs), | ||
v, | ||
m, | ||
) | ||
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any(has_contact.(Ref(c_plus_r), particles)) && continue | ||
push!(particles, c) | ||
end | ||
return particles | ||
end | ||
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function move!(sys::CollisionSystem, pt::Point2D, v::Velocity2D, r::Real=0, Δt=1.) | ||
pt .+= Δt .* v # do not use `pt += v` | ||
if pt.y ≥ sys.ymax - r | ||
pt.y = 2(sys.ymax - r) - pt.y | ||
v.y = -v.y | ||
end | ||
if pt.y ≤ (sys.ymin + r) | ||
pt.y = 2(sys.ymin + r) - pt.y | ||
v.y = -v.y | ||
end | ||
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if pt.x ≥ (sys.xmax - r) | ||
pt.x = 2(sys.xmax - r) - pt.x | ||
v.x = -v.x | ||
end | ||
if pt.x ≤ (sys.xmin + r) | ||
pt.x = 2(sys.xmin + r) - pt.x | ||
v.x = -v.x | ||
end | ||
return pt, v | ||
end | ||
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move!(sys::CollisionSystem, p::Particle2D; Δt=1.) = move!(sys, p.c.pt, p.v, p.c.r, Δt) | ||
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dist(pt1, pt2) = sqrt((pt1.x - pt2.x)^2 + (pt1.y - pt2.y)^2) | ||
has_contact(c1::Circle2D, c2::Circle2D) = c1.r + c2.r ≥ dist(c1.pt, c2.pt) | ||
has_contact(p1::Particle2D, p2::Particle2D) = has_contact(p1.c, p2.c) | ||
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function minifb(sys::CollisionSystem) | ||
particles = setup_particle(sys) | ||
Δt = 0.1 | ||
accumΔt = 0.0 | ||
cnt = 0 | ||
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buf = IOBuffer() | ||
buffer = zeros(UInt32, HEIGHT*WIDTH) | ||
window = mfb_open_ex( | ||
"Elastic Collision 2D", | ||
WIDTH, HEIGHT, | ||
MiniFB.WF_RESIZABLE, | ||
) | ||
while true | ||
accumΔt += Δt | ||
move!.(Ref(sys), particles; Δt) | ||
# naive collision algorithm | ||
for i in 1:length(particles) | ||
for j in (i + 1):length(particles) | ||
particle1 = particles[i] | ||
particle2 = particles[j] | ||
c1 = particle1.c | ||
c2 = particle2.c | ||
# update c1.v and c2.v | ||
if has_contact(c1, c2) | ||
pt1 = c1.pt | ||
pt2 = c2.pt | ||
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v1 = particle1.v | ||
v2 = particle2.v | ||
m1 = particle1.m | ||
m2 = particle2.m | ||
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# correct position so that c1 and c2 does not contact | ||
while has_contact(c1, c2) | ||
c1.pt .-= 0.015 .* v1 | ||
c2.pt .-= 0.015 .* v2 | ||
end | ||
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# update velocity | ||
v1_next = v1 - 2m2 / (m1 + m2) * dot(v1 - v2, pt1 - pt2) * (pt1 - pt2) / dot(pt1 - pt2, pt1 - pt2) | ||
v2_next = v2 - 2m1 / (m2 + m1) * dot(v2 - v1, pt2 - pt1) * (pt2 - pt1) / dot(pt2 - pt1, pt2 - pt1) | ||
particle1.v .= v1_next | ||
particle2.v .= v2_next | ||
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end | ||
end | ||
end | ||
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if accumΔt ≥ 1. | ||
cnt += 1 | ||
s = plot( | ||
size=(WIDTH, HEIGHT), | ||
xlim=(sys.xmin, sys.xmax), ylim=(sys.ymin, sys.ymax), | ||
aspect_ratio=:equal, legend=false, | ||
grid=false, ticks=false, | ||
framestyle=:box, | ||
) | ||
plot!(s, particles) | ||
plot!(s, title="$cnt") | ||
accumΔt = zero(accumΔt) | ||
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show(buf, MIME("image/png"), s) | ||
img = buf |> load | ||
take!(buf) | ||
populate_buffer!(buffer, img) | ||
state = mfb_update(window, buffer) | ||
if state!= MiniFB.STATE_OK | ||
break | ||
end | ||
end | ||
end | ||
mfb_close(window) | ||
end | ||
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minifb(CollisionSystem(;xmin=-8, xmax=8, num_particles=20)) |