ref: f5f4fb16ed24308c78ba1fdc5e84cbcaba53c51c
author: phil9 <telephil9@gmail.com>
date: Fri Dec 23 02:18:23 EST 2022
initial import
--- /dev/null
+++ b/README.md
@@ -1,0 +1,1 @@
+Some graphical algorithms implemented using ![slug]{https://github.com/telephil9/slug}.--- /dev/null
+++ b/marching-squares
@@ -1,0 +1,70 @@
+#!/bin/slug
+
+-- Implementation of the marching squares algorithm
+-- see https://en.wikipedia.org/wiki/Marching_squares
+
+ROWS = 100
+COLS = 100
+mt = {}+
+function b(a, b, c, d)
+ return a*8 + b*4 + c*2 + d
+end
+
+function setup()
+ size(1000, 1000)
+ background(235)
+ stroke(0)
+ strokeWeight(1)
+ for y = 1, ROWS+1 do
+ mt[y] = {}+ for x = 1, COLS+1 do
+ v = 0
+ if math.random() >= 0.5 then v = 1 end
+ mt[y][x] = v
+ end
+ end
+
+ cx = width / ROWS
+ cy = height / COLS
+ for y = 0, ROWS-1 do
+ for x = 0, COLS-1 do
+ n = b(mt[y+1][x+1], mt[y+1][x+2], mt[y+2][x+2], mt[y+2][x+1])
+ if n == 1 then
+ line(x*cx, (y+0.5)*cy, (x+0.5)*cx, (y+1)*cy)
+ elseif n == 2 then
+ line((x+1)*cx, (y+0.5)*cy, (x+0.5)*cx, (y+1)*cy)
+ elseif n == 3 then
+ line(x*cx, (y+0.5)*cy, (x+1)*cx, (y+0.5)*cy)
+ elseif n == 4 then
+ line((x+0.5)*cx, (y+0)*cy, (x+1)*cx, (y+0.5)*cy)
+ elseif n == 5 then
+ line((x)*cx, (y+0.5)*cy, (x+0.5)*cx, (y)*cy)
+ line((x+0.5)*cx, (y+1)*cy, (x+1)*cx, (y+0.5)*cy)
+ elseif n == 6 then
+ line((x+0.5)*cx, y*cy, (x+0.5)*cx, (y+1)*cy)
+ elseif n == 7 then
+ line(x*cx, (y+0.5)*cy, (x+0.5)*cx, y*cy)
+ elseif n == 8 then
+ line(x*cx, (y+0.5)*cy, (x+0.5)*cx, y*cy)
+ elseif n == 9 then
+ line((x+0.5)*cx, y*cy, (x+0.5)*cx, (y+1)*cy)
+ elseif n == 10 then
+ line((x+0.5)*cx, (y+0)*cy, (x+1)*cx, (y+0.5)*cy)
+ line(x*cx, (y+0.5)*cy, (x+0.5)*cx, (y+1)*cy)
+ elseif n == 11 then
+ line((x+0.5)*cx, (y+0)*cy, (x+1)*cx, (y+0.5)*cy)
+ elseif n == 12 then
+ line(x*cx, (y+0.5)*cy, (x+1)*cx, (y+0.5)*cy)
+ elseif n == 13 then
+ line((x+1)*cx, (y+0.5)*cy, (x+0.5)*cx, (y+1)*cy)
+ elseif n == 14 then
+ line(x*cx, (y+0.5)*cy, (x+0.5)*cx, (y+1)*cy)
+ end
+ end
+ end
+end
+
+function draw()
+ noLoop()
+end
--- /dev/null
+++ b/sierpinski-chaos
@@ -1,0 +1,51 @@
+#!/bin/slug
+
+-- Sierpinski triangle generation using the chaos game algorithm
+-- see https://en.wikipedia.org/wiki/Sierpi%C5%84ski_triangle#Chaos_game
+
+x0 = 0
+y0 = 0
+x1 = 0
+y1 = 0
+x2 = 0
+y2 = 0
+x = 0
+y = 0
+
+function setup()
+ size(800, 800)
+ x0 = width/2
+ y0 = 0
+ x1 = 0
+ y1 = height
+ x2 = width
+ y2 = height
+ x = math.floor(math.random(width))
+ y = math.floor(math.random(height))
+ background(0)
+ strokeWeight(2)
+ strokeCap(ROUND)
+end
+
+function draw()
+ for i = 1, 10 do
+ r = math.floor(math.random(3)) - 1
+ if r == 0 then
+ stroke(255, 0, 0)
+ x = math.floor(0.5 + math.lerp(x, x0, 0.5))
+ y = math.floor(0.5 + math.lerp(y, y0, 0.5))
+ circle(x, y, 1)
+ elseif r == 1 then
+ stroke(0, 255, 0)
+ x = math.floor(0.5 + math.lerp(x, x1, 0.5))
+ y = math.floor(0.5 + math.lerp(y, y1, 0.5))
+ circle(x, y, 1)
+ elseif r == 2 then
+ stroke(0, 0, 255)
+ x = math.floor(0.5 + math.lerp(x, x2, 0.5))
+ y = math.floor(0.5 + math.lerp(y, y2, 0.5))
+ circle(x, y, 1)
+ end
+ end
+end
+
--- /dev/null
+++ b/sierpinski-lsystem
@@ -1,0 +1,59 @@
+#!/bin/slug
+
+-- Sierpinski triangle generation using an L-System
+-- see https://en.wikipedia.org/wiki/L-system#Example_5:_Sierpinski_triangle
+
+gen = 0
+start = "F-G-G"
+rules = { F="F-G+F+G-F", G="GG" }+angle = 120
+len = 50
+current = start
+x = 0
+y = 0
+
+function setup()
+ size(1600, 1400)
+end
+
+function evolve()
+ gen = gen + 1
+ next = ""
+ for i = 1, #current do
+ c = string.sub(current, i, i)
+ r = rules[c]
+ if r ~= nil then
+ next = next .. r
+ else
+ next = next .. c
+ end
+ end
+ current = next
+end
+
+function draw()
+ if gen == 6 then
+ noLoop()
+ return
+ end
+ evolve()
+ background(0)
+ stroke(255)
+ strokeWeight(1)
+ x = width / 2
+ y = height-10
+ for i = 1, #current do
+ c = string.sub(current, i, i)
+ if c == "F" or c == "G" then
+ nx = math.floor(0.5 + x + len * math.cos(radians(angle)))
+ ny = math.floor(0.5 + y + len * math.sin(radians(angle)))
+ line(x, y, nx, ny)
+ x = nx
+ y = ny
+ elseif c == "+" then
+ angle = angle - 120
+ elseif c == "-" then
+ angle = angle + 120
+ end
+ end
+end