my 1st turtle
nice page! let the turtle run...
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// created by florian berger (flockaroo) - 2018 // License Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. // my 1st turtle... // turtle torus // You can find the Turtle API reference here: https://turtletoy.net/syntax Canvas.setpenopacity(.25); // Global code will be evaluated once. const turtle = new Turtle(); const nth=16; const nph=32; // The walk function will be called until it returns false. function walk(i) { p0=getTorusPoint(i, 50,20,nph,nth); p1=getTorusPoint(i+1, 50,20,nph,nth); p2=getTorusPoint(i+nth, 50,20,nph,nth); p3=getTorusPoint(i+1+nth,50,20,nph,nth); p0=rotX(1.,p0); p1=rotX(1.,p1); p2=rotX(1.,p2); p3=rotX(1.,p3); p0=project(p0); p1=project(p1); p2=project(p2); p3=project(p3); turtle.penup(); turtle.goto(p1); turtle.pendown(); turtle.goto(p0); turtle.goto(p2); // draw front faces 3 times - not very efficent (at least for the turtle) if(vec3_cross(vec3_sub(p1,p0),vec3_sub(p2,p0))[2]>0.0) { turtle.goto(p3); turtle.goto(p1); turtle.goto(p3); turtle.goto(p2); turtle.goto(p0); turtle.goto(p1); } return i < nph*nth; } function project(p) { p[2]+=180; return [p[0]/p[2]*180.,p[1]/p[2]*180.,p[2]]; } function getTorusPoint(i,R,r,nph,nth) { th=i/nth*Math.PI*2.0; ph=th/nph; return[(R+r*mcos(th))*mcos(ph),(R+r*mcos(th))*msin(ph),r*msin(th)]; } function mcos(x) { return Math.cos(x); } function msin(x) { return Math.sin(x); } function vec3_add(a,b) { return [a[0]+b[0],a[1]+b[1],a[2]+b[2]]; } function vec3_sub(a,b) { return [a[0]-b[0],a[1]-b[1],a[2]-b[2]]; } function vec3_cross(a,b) { return [ a[1]*b[2]-b[1]*a[2], a[2]*b[0]-b[2]*a[0], a[0]*b[1]-b[0]*a[1] ]; } function rotX(ph,v) { return [ v[0],v[1]*mcos(ph)+v[2]*msin(ph), v[2]*mcos(ph)-v[1]*msin(ph) ]; }