// LL 2021

const count = 4; // min=1 max=10 step=1
const thickness = 4; // min=1 max=100 step=1

const iterations = 0; // min=0 max=1000 step=1
const gravity = 0.5; // min=0 max=1 step=0.001

const impulse = 0; //min=0 max=10 step=0.1

const variation = 0.08; // min=0 max=0.2 step=0.01

const seed = 35; // min=0 max=100 step=1

const offset_y = 70;
const scale = 12; // min=1 max=50 step=1
const style = 1; // min=0 max=1 step=1 (Polygons (fast),Polygons (slow))
const draw_crossing = 1; // min=0 max=1 step=1 (No, Yes)

Canvas.setpenopacity(1);

const turtle = new Turtle();

var polygons = null;

var particles = [];
var limbs_to_draw = [];

var iterations_t = iterations;

console.clear();

class Particle {
    constructor(x, y, px, py, radius, floor=0, heavy=false) {
        this.x = x;
        this.y = y;
        this.px = px;
        this.py = py;
        this.radius = radius;
        this.floor = 0;
        this.heavy = heavy;
    }
    
    dup() {
        return new Particle(this.x, this.y, this.px, this.py, this.radius, this.floor, this.heavy);
    }
    
    update() {
        var x = this.x, y = this.y, px = this.px, py = this.py;
        this.px = this.x; this.py = this.y;

        // Verlet
        const friction = 0.99;
        x += (x - px) * friction;
        y += (y - py) * friction;
        
        y += gravity / 100;
        
        const l = getDistance(x, y);
        const rx = rotX(x/l, y/l, Math.PI / 2);
        const ry = rotY(x/l, y/l, Math.PI / 2);

        var dx = x - this.x;
        var dy = y - this.y;
        const l2 = getDistance(dx, dy);
        const max_distance = 0.03;
        if (l2 > max_distance) {
            dx = dx / l2 * max_distance;
            dy = dy / l2 * max_distance;
        }
        
        this.x += dx; this.y += dy;
        
        if (this.y > this.floor - this.radius) this.y = this.floor - this.radius;
    }
}

class Limb {
    constructor(index1, index2, shaded=false) {
        this.index1 = index1;
        this.index2 = index2;
        this.shaded = shaded;
    }

    draw() {
        const astep = 1 / 50;
        const tstep = .25 / scale;

        for (var layer=0; layer<thickness; layer++) {
            const inset = (thickness-1-layer) * tstep;

            const points = [];

            const x1 = particles[this.index1].x;
            const y1 = particles[this.index1].y;
            const r1 = particles[this.index1].radius - inset;
            if (r1 < tstep*0.2) continue;

            if (this.index2 === undefined) {
                for (var a = -1; a <= 1; a += astep) {
                    const dx = rotX(1, 0, a * Math.PI);
                    const dy = rotY(1, 0, a * Math.PI);
                    var px = (x1 + r1 * dx) * scale ;
                    var py = (y1 + r1 * dy) * scale + offset_y;
                    points.push([px, py]);
                }
            } else {
                const x2 = particles[this.index2].x;
                const y2 = particles[this.index2].y;
                const r2 = particles[this.index2].radius - inset;
                if (r2 < tstep*0.2) continue;

                const l = getDistance(x1, y1, x2, y2);
                
                for (var a = -0.5; a <= 0.5; a += astep) {
                    const dx = rotX(x1 - x2, y1 - y2, a * Math.PI) / l;
                    const dy = rotY(x1 - x2, y1 - y2, a * Math.PI) / l;
                    var px = (x1 + r1 * dx) * scale ;
                    var py = (y1 + r1 * dy) * scale + offset_y;
                    points.push([px, py]);
                }
            
                for (var a = -0.5; a <= 0.5; a += astep) {
                    const dx = rotX(x2 - x1, y2 - y1, a * Math.PI) / l;
                    const dy = rotY(x2 - x1, y2 - y1, a * Math.PI) / l;
                    var px = (x2 + r2 * dx) * scale ;
                    var py = (y2 + r2 * dy) * scale + offset_y;
                    points.push([px, py]);
                }
            }
            
            if (style == 0) {
                turtle.jump(points[points.length-1]);
                points.forEach(p=>turtle.goto(p));
            } else {
                const p1 = polygons.create();
                p1.addPoints(...points);
                if (this.shaded) p1.addHatching(-Math.PI/4, 2);
                p1.addOutline();
                polygons.draw(turtle, p1, true);
            }
        }
    }
}

class Spring {
    constructor(index1, index2, is_weak) {
        this.index1 = index1;
        this.is_weak = is_weak;
        if (index2 !== undefined) {
            this.index2 = index2;
            this.length = getDistance(particles[index1].x, particles[index1].y, particles[index2].x, particles[index2].y);
        }
    }
    
    reset() {
        if (this.index2 !== undefined) {
            this.length = getDistance(particles[this.index1].x, particles[this.index1].y, particles[this.index2].x, particles[this.index2].y);
        }
    }
    
    update() {
        if (this.shaded === undefined && this.index2 !== undefined) {
            var x1 = particles[this.index1].x;
            var y1 = particles[this.index1].y;
            var x2 = particles[this.index2].x;
            var y2 = particles[this.index2].y;
            const l = Math.max(0.01, getDistance(x1, y1, x2, y2));
            const diff = this.length - l;
            const strength = this.is_weak ? 0.005 : 0.2;
            // if (!particles[this.index1].heavy) {
                particles[this.index1].x += (x1 - x2) / l * diff * strength;
                particles[this.index1].y += (y1 - y2) / l * diff * strength;
            // }
            // if (!particles[this.index2].heavy) {
                particles[this.index2].x += (x2 - x1) / l * diff * strength;
                particles[this.index2].y += (y2 - y1) / l * diff * strength;
            // }
        }
    }
}

class Puppet {
    constructor(x, y, size) {
        const body_radius = 0.06;
        const head_radius = 0.14;
        
        y += -body_radius * size;
        
        this.limbs = [];
        this.springs = [];
        this.particles = [];

        const start_index = particles.length;
        this.head_index         = this.addParticle(x, y, size,      0,  -1.0, head_radius);
        const neck_index        = this.addParticle(x, y, size,      0,  -0.8, body_radius);
        const belly_index       = this.addParticle(x, y, size,      0,  -0.6, body_radius);
        const bottom_index      = this.addParticle(x, y, size,      0,  -0.4, body_radius);
        const left_elbow_index  = this.addParticle(x, y, size, -0.175, -0.75, body_radius);
        const left_hand_index   = this.addParticle(x, y, size,  -0.35,  -0.6, body_radius);
        const right_elbow_index = this.addParticle(x, y, size,  0.175, -0.65, body_radius);
        const right_hand_index  = this.addParticle(x, y, size,   0.35,  -0.8, body_radius);
        const left_knee_index   = this.addParticle(x, y, size,  -0.09,  -0.2, body_radius);
        const left_foot_index   = this.addParticle(x, y, size,  -0.25,     0, body_radius);
        const right_knee_index  = this.addParticle(x, y, size,    0.2, -0.25, body_radius);
        const right_foot_index  = this.addParticle(x, y, size,    0.2,     0, body_radius);

        // Create the limbs front to back in draw order
        this.limbs.push(new Limb(right_hand_index, right_elbow_index));
        this.limbs.push(new Limb(right_elbow_index, neck_index));
        this.limbs.push(new Limb(right_foot_index, right_knee_index));
        this.limbs.push(new Limb(right_knee_index, bottom_index));
        this.limbs.push(new Limb(this.head_index)); // Just to draw the head
        this.limbs.push(new Limb(this.head_index, neck_index));
        this.limbs.push(new Limb(neck_index, belly_index));
        this.limbs.push(new Limb(belly_index, bottom_index));
        this.limbs.push(new Limb(left_knee_index, bottom_index, true));
        this.limbs.push(new Limb(left_foot_index, left_knee_index, true));
        this.limbs.push(new Limb(left_elbow_index, neck_index, true));
        this.limbs.push(new Limb(left_hand_index, left_elbow_index, true));
        
        for (var i1=0; i1<this.particles.length; i1++) {
            for (var i2=i1+1; i2<this.particles.length; i2++) {
                const is_weak = !this.isLimb(start_index+i1, start_index+i2);
                this.springs.push(new Spring(start_index+i1, start_index+i2, is_weak));
            }
        }
        
        particles[this.head_index].heavy = true;
        particles[this.head_index].floor = -size * 0.9;
    }
    
    pose() {
        this.particles.forEach(p => {
            p.x += variation * (rng.nextFloat() - 0.5) * 10;
            p.y += variation * (rng.nextFloat() - 0.5) * 10;
        });
        
        for (var i=0; i<10; i++) {
            this.springs.forEach(s => {
                if (s.is_weak) {
                    s.reset();
                } else s.update();
            });
        }
    }
    
    impulse() {
        this.particles.forEach(p => {
            p.px += impulse * (rng.nextFloat() - 0.5) * 10;
            p.py += impulse * (rng.nextFloat() - 0.5) * 10;
        });
    }
    
    isLimb(index1, index2) {
        var is_limb = false;
        this.limbs.forEach(l => {
            is_limb |= (l.index1==index1 && l.index2==index2);
            is_limb |= (l.index1==index2 && l.index2==index1);
        });
        return is_limb;
    }
    
    addParticle(ox, oy, size, x, y, radius) {
        var particle = new Particle(ox + x*size, oy + y*size, ox + x*size, oy + y*size, radius*size);
        this.particles.push(particle);
        particles.push(particle);
        return particles.length - 1;
    }
    
    update() {
        this.particles.forEach(p => p.update());
        this.springs.forEach(s => s.update());
    }
    
    queueDraw() {
        this.limbs.forEach(l => {
            limbs_to_draw.push(l);
        });
    }
}

function resolveCollisions() {
    for (var i1=0; i1<particles.length; i1++) {
        //if (!particles[i1].heavy) continue;
        for (var i2=i1+1; i2<particles.length; i2++) {
            //if (!particles[i2].heavy) continue;
            
            var x1 = particles[i1].x;
            var y1 = particles[i1].y;
            var r1 = particles[i1].radius;
            var x2 = particles[i2].x;
            var y2 = particles[i2].y;
            var r2 = particles[i2].radius;
            
            const l = Math.max(0.01, getDistance(x1, y1, x2, y2));
            if (l < (r1 + r2)) {
                const diff = r1 + r2 - l;
                const strength = 0.5;
                particles[i1].x += (x1 - x2) / l * diff * strength;
                particles[i1].y += (y1 - y2) / l * diff * strength;
                particles[i2].x += (x2 - x1) / l * diff * strength;
                particles[i2].y += (y2 - y1) / l * diff * strength;
            }
        }
    }
}

function rotX(x, y, a) { return Math.cos(a) * x - Math.sin(a) * y; }
function rotY(x, y, a) { return Math.sin(a) * x + Math.cos(a) * y; }

function getDistance(x1, y1, x2, y2) {
    if (x2 === undefined) x2 = 0;
    if (y2 === undefined) y2 = 0;
    const dx = x1 - x2, dy = y1 - y2;
    return Math.sqrt(dx*dx + dy*dy);
}

function drawRoad(size) {
    const points = [];
    const near = 2, far = -10, perspective = 5;
    points.push( [-size * scale, near * scale + offset_y] );
    points.push( [ size * scale, near * scale + offset_y] );
    points.push( [ size/perspective * scale, far * scale + offset_y] );
    points.push( [-size/perspective * scale, far * scale + offset_y] );

    const p1 = polygons.create();
    p1.addPoints(...points);
    p1.addHatching(-Math.PI/4, 1);
    p1.addOutline();
    polygons.draw(turtle, p1, true);
}

function drawCrossing(size) {
    const markings = 6;
    const near = 1, far = -4, perspective = 1.75;
    for (var i=0; i<markings; i++) {
        const points = [];
    
        points.push( [(-size + size * 1.8 * (i+0.0) / (markings-1)) * scale, near * scale + offset_y] );
        points.push( [(-size + size * 1.8 * (i+0.5) / (markings-1)) * scale, near * scale + offset_y] );
        points.push( [(-size + size * 1.8 * (i+0.5) / (markings-1))/perspective * scale, far * scale + offset_y] );
        points.push( [(-size + size * 1.8 * (i+0.0) / (markings-1))/perspective * scale, far * scale + offset_y] );


        
        const p1 = polygons.create();
        p1.addPoints(...points);
        p1.addOutline();
        polygons.draw(turtle, p1, true);

   }
   
   drawRoad(size * 1.2);
}

function walk(i, t) {
    if (i==0) {
        iterations_t = iterations * t;
        rng = new RNG(seed);
        particles = [];
        strings_to_draw = [];
        polygons = new Polygons();
        const puppets = [];
        for (var c=0; c<count; c++) {
            const size = 5;
            const x = (c - (count-1) * 0.5) * size * 0.8;
            //const x = (c / Math.max(0.5, count-1) - 0.5) * size;
            const y = 0;
            var puppet = new Puppet(x, 0, 5);

            puppet.pose();

            puppets.push(puppet);
        }
        
        for (var it=0; it<iterations_t; it++) {
            puppets.forEach(puppet => {
                if ((it%10) == 0) puppet.impulse();
                puppet.update();
                resolveCollisions();
            });
        }
            
        puppets.forEach(puppet => {
            puppet.queueDraw();
            // puppet.springs.forEach(s => {
            //     if (s.is_weak) {
            //         turtle.jump(particles[s.index1].x * scale, particles[s.index1].y * scale + offset_y);
            //         turtle.goto(particles[s.index2].x * scale, particles[s.index2].y * scale + offset_y);
            //     }
            // });
        });
    }
    
    if (limbs_to_draw.length < 1) {
        if (style == 1 && draw_crossing) drawCrossing(20);
        return false;
    }

    limbs_to_draw.shift().draw();

    return true;
}

////

function sleep(milliseconds) {
  const date = Date.now();
  let currentDate = null;
  do {
    currentDate = Date.now();
  } while (currentDate - date < milliseconds);
}

//// Random with seed

function RNG(_seed) {
  // LCG using GCC's constants
  this.m = 0x80000000; // 2**31;
  this.a = 1103515245;
  this.c = 12345;

  this.state = _seed ? _seed : Math.floor(Math.random() * (this.m - 1));
}
RNG.prototype.nextFloat = function() {
  // returns in range [0,1]
  this.state = (this.a * this.state + this.c) % this.m;
  return this.state / (this.m - 1);
}

var rng = new RNG(seed);

////////////////////////////////////////////////////////////////
// Polygon Clipping utility code - Created by Reinder Nijhoff 2019
// https://turtletoy.net/turtle/a5befa1f8d
////////////////////////////////////////////////////////////////

function Polygons() {
	const polygonList = [];
	const Polygon = class {
		constructor() {
			this.cp = [];       // clip path: array of [x,y] pairs
			this.dp = [];       // 2d lines [x0,y0],[x1,y1] to draw
			this.aabb = [];     // AABB bounding box
		}
		addPoints(...points) {
		    // add point to clip path and update bounding box
		    let xmin = 1e5, xmax = -1e5, ymin = 1e5, ymax = -1e5;
			(this.cp = [...this.cp, ...points]).forEach( p => {
				xmin = Math.min(xmin, p[0]), xmax = Math.max(xmax, p[0]);
				ymin = Math.min(ymin, p[1]), ymax = Math.max(ymax, p[1]);
			});
		    this.aabb = [(xmin+xmax)/2, (ymin+ymax)/2, (xmax-xmin)/2, (ymax-ymin)/2];
		}
		addSegments(...points) {
		    // add segments (each a pair of points)
		    points.forEach(p => this.dp.push(p));
		}
		addOutline() {
			for (let i = 0, l = this.cp.length; i < l; i++) {
				this.dp.push(this.cp[i], this.cp[(i + 1) % l]);
			}
		}
		draw(t) {
			for (let i = 0, l = this.dp.length; i < l; i+=2) {
				t.jump(this.dp[i]), t.goto(this.dp[i + 1]);
			}
		}
		addHatching(a, d) {
			const tp = new Polygon();
			tp.cp.push([-1e5,-1e5],[1e5,-1e5],[1e5,1e5],[-1e5,1e5]);
			const dx = Math.sin(a) * d,   dy = Math.cos(a) * d;
			const cx = Math.sin(a) * 200, cy = Math.cos(a) * 200;
			for (let i = 0.5; i < 150 / d; i++) {
				tp.dp.push([dx * i + cy,   dy * i - cx], [dx * i - cy,   dy * i + cx]);
				tp.dp.push([-dx * i + cy, -dy * i - cx], [-dx * i - cy, -dy * i + cx]);
			}
			tp.boolean(this, false);
			this.dp = [...this.dp, ...tp.dp];
		}
		inside(p) {
			let int = 0; // find number of i ntersection points from p to far away
			for (let i = 0, l = this.cp.length; i < l; i++) {
				if (this.segment_intersect(p, [0.1, -1000], this.cp[i], this.cp[(i + 1) % l])) {
					int++;
				}
			}
			return int & 1; // if even your outside
		}
		boolean(p, diff = true) {
		    // bouding box optimization by ge1doot.
		    if (Math.abs(this.aabb[0] - p.aabb[0]) - (p.aabb[2] + this.aabb[2]) >= 0 &&
				Math.abs(this.aabb[1] - p.aabb[1]) - (p.aabb[3] + this.aabb[3]) >= 0) return this.dp.length > 0;
				
			// polygon diff algorithm (narrow phase)
			const ndp = [];
			for (let i = 0, l = this.dp.length; i < l; i+=2) {
				const ls0 = this.dp[i];
				const ls1 = this.dp[i + 1];
				// find all intersections with clip path
				const int = [];
				for (let j = 0, cl = p.cp.length; j < cl; j++) {
					const pint = this.segment_intersect(ls0, ls1, p.cp[j], p.cp[(j + 1) % cl]);
					if (pint !== false) {
						int.push(pint);
					}
				}
				if (int.length === 0) {
					// 0 intersections, inside or outside?
					if (diff === !p.inside(ls0)) {
						ndp.push(ls0, ls1);
					}
				} else {
					int.push(ls0, ls1);
					// order intersection points on line ls.p1 to ls.p2
					const cmpx = ls1[0] - ls0[0];
					const cmpy = ls1[1] - ls0[1];
					int.sort( (a,b) =>  (a[0] - ls0[0]) * cmpx + (a[1] - ls0[1]) * cmpy - 
					                    (b[0] - ls0[0]) * cmpx - (b[1] - ls0[1]) * cmpy);
					 
					for (let j = 0; j < int.length - 1; j++) {
						if ((int[j][0] - int[j+1][0])**2 + (int[j][1] - int[j+1][1])**2 >= 0.001) {
							if (diff === !p.inside([(int[j][0]+int[j+1][0])/2,(int[j][1]+int[j+1][1])/2])) {
								ndp.push(int[j], int[j+1]);
							}
						}
					}
				}
			}
			return (this.dp = ndp).length > 0;
		}
		//port of http://paulbourke.net/geometry/pointlineplane/Helpers.cs
		segment_intersect(l1p1, l1p2, l2p1, l2p2) {
			const d   = (l2p2[1] - l2p1[1]) * (l1p2[0] - l1p1[0]) - (l2p2[0] - l2p1[0]) * (l1p2[1] - l1p1[1]);
			if (d === 0) return false;
			const n_a = (l2p2[0] - l2p1[0]) * (l1p1[1] - l2p1[1]) - (l2p2[1] - l2p1[1]) * (l1p1[0] - l2p1[0]);
			const n_b = (l1p2[0] - l1p1[0]) * (l1p1[1] - l2p1[1]) - (l1p2[1] - l1p1[1]) * (l1p1[0] - l2p1[0]);
			const ua = n_a / d;
			const ub = n_b / d;
			if (ua >= 0 && ua <= 1 && ub >= 0 && ub <= 1) {
				return [l1p1[0] + ua * (l1p2[0] - l1p1[0]), l1p1[1] + ua * (l1p2[1] - l1p1[1])];
			}
			return false;
		}
	};
	return {
		list: () => polygonList,
		create: () => new Polygon(),
		draw: (turtle, p, addToVisList=true) => {
			for (let j = 0; j < polygonList.length && p.boolean(polygonList[j]); j++);
			p.draw(turtle);
			if (addToVisList) polygonList.push(p);
		}
	};
}