From f1fd2797a4a0c956a4bf0adff2959c103b38d78a Mon Sep 17 00:00:00 2001
From: Justin Lin <justin.sdk@gmail.com>
Date: Thu, 23 Jun 2022 18:36:25 +0800
Subject: [PATCH] add foliage_scroll

---
 src/experimental/foliage_scroll.scad | 140 +++++++++++++++++++++++++++
 1 file changed, 140 insertions(+)
 create mode 100644 src/experimental/foliage_scroll.scad

diff --git a/src/experimental/foliage_scroll.scad b/src/experimental/foliage_scroll.scad
new file mode 100644
index 00000000..43e42f68
--- /dev/null
+++ b/src/experimental/foliage_scroll.scad
@@ -0,0 +1,140 @@
+TAU = 360;
+
+MAX_ANGLE = 720;
+
+function vt(center, r, startAngle, angleSign, angle) = 
+    let(
+        a = angle * angleSign + startAngle,
+        s = (MAX_ANGLE - angle) / MAX_ANGLE
+    )
+    [
+        center.x + r * cos(a) * s, 
+        center.y + r * sin(a) * s
+    ];
+
+function spiral(center, r, startAngle, angleSign = 1, angle = 0, path) = 
+[
+    center, 
+    r, 
+    startAngle,
+    angleSign,
+    angle,
+    is_undef(path) ? [vt(center, r, startAngle, angleSign, angle)] :  path
+];
+
+function spiral_center(spiral) = spiral[0];
+function spiral_r(spiral) = spiral[1];
+function spiral_startAngle(spiral) = spiral[2];
+function spiral_angleSign(spiral) = spiral[3];
+function spiral_angle(spiral) = spiral[4];
+function spiral_path(spiral) = spiral[5];
+
+function spiral_step(spiral, angleStep) = 
+    let(    
+        c = spiral_center(spiral),
+        r = spiral_r(spiral),
+        sa = spiral_startAngle(spiral),
+        as = spiral_angleSign(spiral),
+        a = spiral_angle(spiral) + angleStep
+        
+    )
+    spiral(
+        c,
+        r,
+        sa,
+        as,
+        a,
+        [each spiral_path(spiral), vt(c, r, sa, as, a)]
+    );
+    
+
+function foliage_scroll(width, height, spirals, maxSpirals, minR, done = 0) =
+    let(
+        more_spirals = try_add_spiral(width, height, spirals, maxSpirals, minR, done),
+        nx_spirals = [
+            for(i = 0; i < len(more_spirals); i = i + 1)
+            if(i < done) more_spirals[i] else spiral_step(more_spirals[i], angleStep)
+        ],
+        nx_done = count(nx_spirals, function(s) spiral_angle(s) > 630)
+    )
+    nx_done < len(nx_spirals)? foliage_scroll(width, height, nx_spirals, maxSpirals, minR, nx_done) : nx_spirals;
+
+function try_add_spiral(width, height, spirals, maxSpirals, minR, done) = 
+    let(
+        leng = len(spirals),
+        more_spirals = [
+            each spirals,
+            each [
+                for(i = done; i < leng; i = i + 1) 
+                let(maybeSpiral = try_create_spiral(width, height, spirals, i, minR))
+                if(!is_undef(maybeSpiral)) maybeSpiral
+            ]
+        ],
+        leng_more_spirals = len(more_spirals)
+    )
+    leng_more_spirals > maxSpirals ? [for(i = [0:maxSpirals - 1]) more_spirals[i]] : more_spirals;
+    
+function try_create_spiral(width, height, spirals, i, minR) = 
+    let(spiral = spirals[i])
+    spiral_angle(spiral) <= 270 ? undef :
+    let(
+        r = spiral_r(spiral),
+        cr = r * rands(0.5, 1.75, 1)[0]
+    )
+    cr < minR ? undef : 
+    let(
+        offAngle = rands(0, 270, 1)[0],
+        offR = r * (MAX_ANGLE - offAngle) / MAX_ANGLE + cr,
+        angleSign = spiral_angleSign(spiral),
+        ca = offAngle * angleSign + spiral_startAngle(spiral) + 180,
+        center = spiral_center(spiral),
+        cx = center.x + offR * cos(ca - 180),
+        cy = center.y + offR * sin(ca - 180)
+    )
+    out_size(width, height, cx, cy, cr) || overlapped(spirals, i, cx, cy, cr) ? undef : spiral([cx, cy], cr, ca, -angleSign);
+
+function out_size(width, height, cx, cy, cr) =
+    cx < -width / 2 + cr || cx > width / 2 - cr || cy < -height / 2 + cr || cy > height / 2 - cr;
+    
+function overlapped(spirals, i, cx, cy, cr, j = 0) = 
+    j == len(spirals) ? false :
+    j == i ? overlapped(spirals, i, cx, cy, cr, j + 1) :
+    let(
+        spiral = spirals[j],
+        leng = norm(spiral_center(spiral) - [cx, cy]),
+        sa = startAngle(cx, cy, spiral),
+        d = cr * 1.5,
+        r = spiral_r(spiral)
+    )
+    dist(leng, r, sa) <  d || dist(leng, r, sa + 360) < d || overlapped(spirals, i, cx, cy, cr, j + 1);
+    
+function startAngle(cx, cy, spiral) = 
+    let(
+        center = spiral_center(spiral),
+        sa = (atan2((cy - center.y), (cx - center.x)) - spiral_startAngle(spiral)) % 360
+    )
+    abs((sa + spiral_angleSign(spiral) * 360) % 360);
+    
+function dist(leng, r, a) = abs(leng - r * (MAX_ANGLE - a) / MAX_ANGLE);
+
+use <polyline_join.scad>
+use <util/count.scad>
+
+width = 400;
+height = 400;
+maxSpirals = 100; 
+angleStep = 10; 
+minR = 10; 
+
+r = rands(minR * 2, minR * 4, 1)[0];
+
+spirals = [
+    spiral([r, 0], r, 180),
+    spiral([-r, 0], r, 0)
+];
+
+ss = foliage_scroll(width, height, spirals, maxSpirals, minR);
+for(s = ss) {
+    polyline_join(spiral_path(s))
+        circle(minR / 5);
+}
\ No newline at end of file