Adding some (commented out) support for generating iso surfaces.

[aweather] / src / marching.h

diff --git a/src/marching.h b/src/marching.h
new file mode 100644 (file)
index 0000000..b1186f5
--- /dev/null
+++ b/src/marching.h
@@ -0,0 +1,80 @@
+/**
+ * Copyright (c) 2002 Jamie Zawinski <jwz@jwz.org>
+ * Copyright (c) 2009 Andy Spencer <andy753421@gmail.com>
+ *
+ * Utility functions to create "marching cubes" meshes from 3d fields.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation.  No representations are made about the suitability of this
+ * software for any purpose.  It is provided "as is" without express or 
+ * implied warranty.
+ */
+
+#ifndef __MARCHING_H__
+#define __MARCHING_H__
+
+typedef struct {
+       double x;
+       double y;
+       double z;
+} XYZ;
+
+typedef struct {
+   XYZ p[3];
+} TRIANGLE;
+
+typedef struct {
+   XYZ p[8];
+   double val[8];
+} GRIDCELL;
+
+int march_one_cube(GRIDCELL grid, double isolevel, TRIANGLE *triangles);
+
+void do_function_normal (double x, double y, double z,
+               double (*compute_fn) (double x, double y, double z,
+                       void *closure),
+               void *c);
+
+XYZ calc_normal (XYZ p, XYZ p1, XYZ p2);
+
+void do_normal(float x1, float y1, float z1,
+               float x2, float y2, float z2,
+               float x3, float y3, float z3);
+
+
+/* Given a function capable of generating a value at any XYZ position,
+   creates OpenGL faces for the solids defined.
+
+   init_fn is called at the beginning for initial, and returns an object.
+   free_fn is called at the end.
+
+   compute_fn is called for each XYZ in the specified grid, and returns
+   the double value of that coordinate.  If smoothing is on, then
+   compute_fn will also be called twice more for each emitted vertex,
+   in order to calculate vertex normals (so don't assume it will only
+   be called with values falling on the grid boundaries.)
+
+   Points are inside an object if the are less than `isolevel', and
+   outside otherwise.
+
+   If polygon_count is specified, the number of faces generated will be
+   returned there.
+*/
+extern void
+marching_cubes (int grid_size,     /* density of the mesh */
+                double isolevel,   /* cutoff point for "in" versus "out" */
+                int wireframe_p,   /* wireframe, or solid */
+                int smooth_p,      /* smooth, or faceted */
+
+                void * (*init_fn)    (double grid_size, void *closure1),
+                double (*compute_fn) (double x, double y, double z,
+                                      void *closure2),
+                void   (*free_fn)    (void *closure2),
+                void *closure1,
+
+                unsigned long *polygon_count);
+
+#endif /* __MARCHING_H__ */