From ade18af430afeed44b6e75b3104ffa9ea5e082e5 Mon Sep 17 00:00:00 2001
From: Justin Lin <caterpillar@openhome.cc>
Date: Sat, 10 Aug 2019 10:15:21 +0800
Subject: [PATCH] add forest

---
 examples/forest.scad | 105 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 examples/forest.scad

diff --git a/examples/forest.scad b/examples/forest.scad
new file mode 100644
index 00000000..d19ee699
--- /dev/null
+++ b/examples/forest.scad
@@ -0,0 +1,105 @@
+include <line2d.scad>;
+include <turtle/turtle2d.scad>;
+
+style = "MIRROR"; // [TREES, INVERTED, MIRROR]
+trunk_angle = 86; // [1:90]
+max_trunk_length = 400;
+min_trunk_length = 2;
+width = 1.5;
+k1 = 1.5;
+k2 = 1.0;
+
+// Style: TREES, INVERTED, MIRROR
+module forest(trunk_angle, max_trunk_length, min_trunk_length, style = "TREES", k1 = 1.5, k2 = 1.0, width = 1) {
+	k = 1.0 / (k1 + 2 *  k2 + 2 * (k1 +  k2) * cos(trunk_angle));
+	
+    function forward(t, leng) = turtle2d("forward", t, leng);
+    function turn(t, ang) = turtle2d("turn", t, ang);
+    function pt(t) = turtle2d("pt", t);
+    
+	module trunk(t, length) {
+        if (length > min_trunk_length) {
+		    // baseline
+			if(style != "INVERTED") {
+			    line2d(t[0], pt(forward(t, length)), width);
+			} else {
+			    inverted_trunk(t, length);
+			}
+			
+			if(style == "MIRROR") {
+				 mirror([0, 1, 0]) inverted_trunk(t, length);
+			} 
+			
+			trunk(t, k * k1 * length);
+			
+			// left side of "k * k1 * length" trunks
+			t1 = turn(
+			    forward(t, k * k1 * length),
+				trunk_angle
+			);			
+			trunk(t1, k * k1 * length);
+			
+			// right side of "k * k1 * length" trunks
+			t2 = turn(
+			    forward(t1, k * k1 * length), 
+				-2 * trunk_angle
+			);
+			trunk(t2, k * k1 * length);
+			
+			// "k * length" trunks
+			t3 = turn(
+			    forward(t2, k * k1 * length), 
+				trunk_angle
+			);
+			trunk(t3, k * length);
+			
+			// left side of "k *  k2 * length" trunks
+			t4 = turn(
+			    forward(t3, k * length), trunk_angle
+			);
+			trunk(t4, k *  k2 * length);
+			
+			// right side of "k *  k2 * length" trunks
+			t5 = turn(
+			    forward(t4, k *  k2 * length), -2 * trunk_angle
+		    );
+			trunk(t5, k *  k2 * length);
+		
+		    // "k *  k2 * length" trunks
+			trunk(
+			    turn(
+				    forward(t5, k *  k2 * length), 
+					trunk_angle
+				), 
+				k *  k2 * length
+			);
+        }
+	}
+	 
+	module inverted_trunk(t, length) {
+	    
+		if(k * k1 * length > min_trunk_length) {
+			t1 = forward(t, k * k1 * length);
+			t2 = forward(turn(t1, trunk_angle), k * k1 * length);
+			t3 = forward(turn(t2, -2 * trunk_angle), k * k1 * length);
+			offset(r = width * 0.25) polygon([t1[0], t2[0], t3[0]]);
+			
+			if(k * length > min_trunk_length && k * k2 * length > min_trunk_length) {
+				t4 = forward(turn(t3, trunk_angle), k * length);				
+				t5 = forward(turn(t4, trunk_angle), k * k2 * length);
+				t6 = forward(turn(t5, -2 * trunk_angle), k * k2 * length);
+				offset(r = width * 0.25) polygon([t4[0], t5[0], t6[0]]);
+		        
+			}
+		}
+	}
+	
+    trunk(turtle2d("create", 0, 0, 0), max_trunk_length);
+	
+	if(style == "INVERTED") {
+	    line2d([0, 0], [max_trunk_length, 0], width);
+	}
+}
+
+
+forest(trunk_angle, max_trunk_length, min_trunk_length, style, k1, k2, width);