X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=reprap-play.git;a=blobdiff_plain;f=funcs.scad.cpp;h=5857c933a837f888bf22faedda5b455e6df0e973;hp=29d5a1e6dd2ab9bc0a103ad28203d98e20a7dd29;hb=f1824fce4c0b4420e0ba377d8d8a4e43e42e4a7d;hpb=f57afd91759a049296c6d454b2e3a2b46a5560f7

diff --git a/funcs.scad.cpp b/funcs.scad.cpp
index 29d5a1e..5857c93 100644
--- a/funcs.scad.cpp
+++ b/funcs.scad.cpp
@@ -1,14 +1,63 @@
 // -*- C -*-
 
-function dist(a,b) =
+function vecdiff2d(a,b) = [b[0]-a[0], b[1]-a[1]];
+function vecdiff(a,b)   = [b[0]-a[0], b[1]-a[1], b[2]-a[2]];
+
 #define dsq(i) (a[i]-b[i])*(a[i]-b[i])
-	       sqrt(dsq(0) + dsq(1));
+function dist2d(a,b) = sqrt(dsq(0) + dsq(1));
+function dist(a,b)   = sqrt(dsq(0) + dsq(1) + dsq(2));
 #undef dsq
 
+#define vsq(i) (v[i]*v[i])
+function vectorlen2d(v) = sqrt(vsq(0) + vsq(1));
+function vectorlen(v)   = sqrt(vsq(0) + vsq(1) + vsq(2));
+#undef vsq
+
+function unitvector2d(v) = v / vectorlen2d(v);
+function unitvector(v)   = v / vectorlen(v);
+
+function atan2vector(v) = atan2(v[1], v[0]);
+
+// | m[0][0] m[0][1] |
+// | m[1][0] m[1][1] |
+function determinant2(m) = (m[0][0] * m[1][1] - m[0][1] * m[1][0]);
+
+function clockwise2d(v) = [v[1], -v[0]];
+
+// intersection of lines p1..p2 and p3..p4
+function line_intersection_2d(p1,p2,p3,p4) = [
+  // from https://en.wikipedia.org/wiki/Line%E2%80%93line_intersection#Given_two_points_on_each_line
+  #define XY12 determinant2([p1,p2])
+  #define XY34 determinant2([p3,p4])
+  #define XU12 QU(0,1,2)
+  #define XU34 QU(0,3,4)
+  #define YU12 QU(1,1,2)
+  #define YU34 QU(1,3,4)
+  #define QU(c,i,j) determinant2([[ p##i[c], 1 ], \
+				 [ p##j[c], 1 ]])
+  #define DENOM \
+   determinant2([[ XU12, YU12 ], \
+		 [ XU34, YU34 ]])
+   //----
+   determinant2([[ XY12, XU12 ],
+		 [ XY34, XU34 ]]) / DENOM,
+   determinant2([[ XY12, YU12 ],
+		 [ XY34, YU34 ]]) / DENOM,
+   ];
+  #undef XY12
+  #undef XY34
+  #undef XU12
+  #undef XU34
+  #undef YU12
+  #undef YU34
+  #undef QU
+  #undef DENOM
+
+
 function circle_point(c, r, alpha) = [ c[0] + r * cos(alpha),
 				       c[1] + r * sin(alpha) ];
 
-#define d     (dist(a,c))
+#define d     (dist2d(a,c))
 #define alpha (atan2(a[1]-c[1],a[0]-c[0]))
 #define gamma (asin(r / d))
 #define beta  (alpha + 90 - gamma)
@@ -23,5 +72,12 @@ function tangent_intersect_b(c,r,a) =
 #undef gamma
 #undef beta
 
+function tangents_intersect_beta(cbig,rbig,csmall,rsmall) =
+        tangent_intersect_beta(cbig,rbig-rsmall,csmall);
+
 function reflect_in_y(p) = [-p[0], p[1]];
 
+function angle_map_range(in,base) =
+  in <  base       ? in + 360 :
+  in >= base + 360 ? in - 360 :
+  in;