1 files changed, 272 insertions, 0 deletions
diff --git a/lib/vector.c b/lib/vector.c
new file mode 100644
index 0000000..354af2d
--- /dev/null
+++ b/lib/vector.c
@@ -0,0 +1,272 @@
+/* vector.c: vector/point operations.
+
+Copyright (C) 1992 Free Software Foundation, Inc.
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#include "config.h"
+
+#include "vector.h"
+
+
+/* Given the point COORD, return the corresponding vector.  */
+
+const vector_type
+make_vector (const real_coordinate_type c)
+{
+  vector_type v;
+
+  v.dx = c.x;
+  v.dy = c.y;
+
+  return v;
+}
+
+
+/* And the converse: given a vector, return the corresponding point.  */
+
+const real_coordinate_type
+vector_to_point (const vector_type v)
+{
+  real_coordinate_type coord;
+
+  coord.x = v.dx;
+  coord.y = v.dy;
+
+  return coord;
+}
+
+
+
+const real
+magnitude (const vector_type v)
+{
+  return hypot (v.dx, v.dy);
+}
+
+
+const vector_type
+normalize (const vector_type v)
+{
+  vector_type new_v;
+  real m = magnitude (v);
+
+  assert (m > 0.0);
+
+  new_v.dx = v.dx / m;
+  new_v.dy = v.dy / m;
+
+  return new_v;
+}
+
+
+const vector_type
+Vadd (const vector_type v1, const vector_type v2)
+{
+  vector_type new_v;
+
+  new_v.dx = v1.dx + v2.dx;
+  new_v.dy = v1.dy + v2.dy;
+
+  return new_v;
+}
+
+
+const real
+Vdot (const vector_type v1, const vector_type v2)
+{
+  return v1.dx * v2.dx + v1.dy * v2.dy;
+}
+
+
+const vector_type
+Vmult_scalar (const vector_type v, const real r)
+{
+  vector_type new_v;
+
+  new_v.dx = v.dx * r;
+  new_v.dy = v.dy * r;
+
+  return new_v;
+}
+
+
+/* Given the IN_VECTOR and OUT_VECTOR, return the angle between them in
+   degrees, in the range zero to 180.  */
+   
+const real
+Vangle (const vector_type in_vector, const vector_type out_vector)
+{
+  vector_type v1 = normalize (in_vector);
+  vector_type v2 = normalize (out_vector);
+
+  return acosd (Vdot (v2, v1));
+}
+
+
+const real_coordinate_type
+Vadd_point (const real_coordinate_type c, const vector_type v)
+{
+  real_coordinate_type new_c;
+
+  new_c.x = c.x + v.dx;
+  new_c.y = c.y + v.dy;
+  return new_c;
+}
+
+
+const real_coordinate_type
+Vsubtract_point (const real_coordinate_type c, const vector_type v)
+{
+  real_coordinate_type new_c;
+
+  new_c.x = c.x - v.dx;
+  new_c.y = c.y - v.dy;
+  return new_c;
+}
+
+
+const coordinate_type
+Vadd_int_point (const coordinate_type c, const vector_type v)
+{
+  coordinate_type a;
+  
+  a.x = ROUND ((real) c.x + v.dx);
+  a.y = ROUND ((real) c.y + v.dy);
+  return a;
+}
+
+
+const vector_type
+Vabs (const vector_type v)
+{
+  vector_type new_v;
+  
+  new_v.dx = fabs (v.dx);
+  new_v.dy = fabs (v.dy);
+  return new_v;
+}
+
+
+
+/* Operations on points.  */
+
+/* This is a macro now.  */
+#if 0
+const real_coordinate_type
+Padd (real_coordinate_type coord1, real_coordinate_type coord2)
+{
+  real_coordinate_type sum;
+
+  sum.x = coord1.x + coord2.x;
+  sum.y = coord1.y + coord2.y;
+
+  return sum;
+}
+
+
+const real_coordinate_type
+Pmult_scalar (const real_coordinate_type coord, const real r)
+{
+  real_coordinate_type answer;
+
+  answer.x = coord.x * r;
+  answer.y = coord.y * r;
+
+  return answer;
+}
+#endif /* 0 */
+
+
+const vector_type
+Psubtract (const real_coordinate_type c1, const real_coordinate_type c2)
+{
+  vector_type v;
+
+  v.dx = c1.x - c2.x;
+  v.dy = c1.y - c2.y;
+
+  return v;
+}
+
+
+
+/* Operations on integer points.  */
+
+const vector_type
+IPsubtract (const coordinate_type coord1, const coordinate_type coord2)
+{
+  vector_type v;
+
+  v.dx = coord1.x - coord2.x;
+  v.dy = coord1.y - coord2.y;
+
+  return v;
+}
+
+
+const coordinate_type
+IPsubtractP (const coordinate_type c1, const coordinate_type c2)
+{
+  coordinate_type c;
+  
+  c.x = c1.x - c2.x;
+  c.y = c1.y - c2.y;
+  
+  return c;
+}
+
+
+const coordinate_type
+IPadd (const coordinate_type c1, const coordinate_type c2)
+{
+  coordinate_type c;
+  
+  c.x = c1.x + c2.x;
+  c.y = c1.y + c2.y;
+  
+  return c;
+}
+
+
+const coordinate_type
+IPmult_scalar (const coordinate_type c, const int i)
+{
+  coordinate_type a;
+  
+  a.x = c.x * i;
+  a.y = c.y * i;
+  
+  return a;
+}
+
+
+const real_coordinate_type
+IPmult_real (const coordinate_type c, const real r)
+{
+  real_coordinate_type a;
+
+  a.x = c.x * r;
+  a.y = c.y * r;
+
+  return a;
+}
+
+
+const boolean
+IPequal (const coordinate_type c1, const coordinate_type c2)
+{
+  return c1.x == c2.x && c1.y == c2.y;
+}