I have been thru it many times and it seems correct, but can't be :-(
[/code]
set display mode 1920,1080,32
sync on :sync rate 60
autocam off
r1#=125.0
r2#=125.0
m1#=10.0
m2#=10.0
a1#=90.0
a2#=90.0
a1_v# = 0.0
a2_v# = 0.0
`a1_a# = 1
`a2_a# = 1
g# = 1.0
px2# = -1.0
py2# = -1.0
`````````````````````````````````
do
cls
inc delay
ink rgb(0,200,0)
`text 20,20,str$(screen fps())+" "+str$(a)+" "+str$(1920/120)
num1# = -g# * (m1# + m2# * 2) * sin(a1#)
num2# = -m2# * g# * sin(a1#-2 * a2#)
num3# = -2 * sin(a1# - a2#) * m2#
num4# = (a2_v# * a2_v#) * r2# + (a1_v# * a1_v#) * r1# * cos(a1# - a2#)
den# = r1# * (2 *m1# + m2# - m2# * cos(2 * a1# - 2 * a2#))
a1_a# = (num1# + num2# + num3# * num4#) / den#
num11# = 2 * sin(a1# - a2#)
num21# = ((a1_v# * a1_v#) * r1# * (m1# + m2#))
num31# = g# * (m1# + m2#) * cos(a1#)
num41# = a2_v# * a2_v# * r2# * m2# * cos(a1# - a2#)
den1# = r2# * (2 * m1# + m2# - m2# * cos(2 * a1# - 2 * a2#))
a2_a# = (num11# * (num21# + num31# + num41#)) / den1#
remstart
let num1 = -g * (2 * m1 + m2) * sin(a1);
let num2 = -m2 * g * sin(a1 - 2 * a2);
let num3 = -2 * sin(a1 - a2) * m2;
let num4 = a2_v * a2_v * r2 + a1_v * a1_v * r1 * cos(a1 - a2);
let den = r1 * (2 * m1 + m2 - m2 * cos(2 * a1 - 2 * a2));
let a1_a = (num1 + num2 + num3 * num4) / den;
num1 = 2 * sin(a1 - a2);
num2 = (a1_v * a1_v * r1 * (m1 + m2));
num3 = g * (m1 + m2) * cos(a1);
num4 = a2_v * a2_v * r2 * m2 * cos(a1 - a2);
den = r2 * (2 * m1 + m2 - m2 * cos(2 * a1 - 2 * a2));
let a2_a = (num1 * (num2 + num3 + num4)) / den;
remend
` translate(cx, cy);
` stroke(0);
` strokeWeight(2);
x1# =960 + r1# * sin(a1#)
y1# =250 + r1# * cos(a1#)
x2# = x1# + r2# * sin(a2#)
y2# = y1# + r2# * cos(a2#)
line 960,250,x1#,y1#
line x1#,y1#,x2#,y2#
a1_v# = a1_v#+a1_a#
a2_v# = a2_v#+a2_a#
a1# = a1# +a1_v#
a2# = a2# +a2_v#
` a1_v# = a1_v# *0.9995
` a2_v# = a2_v# *0.9995
` px2# = x2#
` py2# = y2#
ttt:
if inkey$()=" " then goto ttt
sync
loop
[code lang=dbp]
Original code...
// Daniel Shiffman
// https://thecodingtrain.com/CodingChallenges/093-double-pendulum.html
// https://youtu.be/uWzPe_S-RVE
let r1 = 125;
let r2 = 125;
let m1 = 10;
let m2 = 10;
let a1 = 0;
let a2 = 0;
let a1_v = 0;
let a2_v = 0;
let g = 1;
let px2 = -1;
let py2 = -1;
let cx, cy;
let buffer;
function setup() {
createCanvas(500, 300);
//Issue with wrong rendering on a retina Mac. See issue: https://github.com/CodingTrain/website/issues/574
pixelDensity(1);
a1 = PI / 2;
a2 = PI / 2;
cx = width / 2;
cy = 50;
buffer = createGraphics(width, height);
buffer.background(175);
buffer.translate(cx, cy);
}
function draw() {
background(175);
imageMode(CORNER);
image(buffer, 0, 0, width, height);
let num1 = -g * (2 * m1 + m2) * sin(a1);
let num2 = -m2 * g * sin(a1 - 2 * a2);
let num3 = -2 * sin(a1 - a2) * m2;
let num4 = a2_v * a2_v * r2 + a1_v * a1_v * r1 * cos(a1 - a2);
let den = r1 * (2 * m1 + m2 - m2 * cos(2 * a1 - 2 * a2));
let a1_a = (num1 + num2 + num3 * num4) / den;
num1 = 2 * sin(a1 - a2);
num2 = (a1_v * a1_v * r1 * (m1 + m2));
num3 = g * (m1 + m2) * cos(a1);
num4 = a2_v * a2_v * r2 * m2 * cos(a1 - a2);
den = r2 * (2 * m1 + m2 - m2 * cos(2 * a1 - 2 * a2));
let a2_a = (num1 * (num2 + num3 + num4)) / den;
translate(cx, cy);
stroke(0);
strokeWeight(2);
let x1 = r1 * sin(a1);
let y1 = r1 * cos(a1);
let x2 = x1 + r2 * sin(a2);
let y2 = y1 + r2 * cos(a2);
line(0, 0, x1, y1);
fill(0);
ellipse(x1, y1, m1, m1);
line(x1, y1, x2, y2);
fill(0);
ellipse(x2, y2, m2, m2);
a1_v += a1_a;
a2_v += a2_a;
a1 += a1_v;
a2 += a2_v;
// a1_v *= 0.99;
// a2_v *= 0.99;
buffer.stroke(0);
if (frameCount > 1) {
buffer.line(px2, py2, x2, y2);
}
px2 = x2;
py2 = y2;
}
