* First commit merging 2.4-based sim_physics in to volume25 branch.

Integration is still very rough around the edges and WIP, but it works, and can render smoke (using new Smoke format in Voxel Data texture) --> http://vimeo.com/6030983

More to come, but this makes things much easier to work on for me :)

1 files changed, 299 insertions, 0 deletions

diff --git a/source/blender/blenlib/intern/voxel.c b/source/blender/blenlib/intern/voxel.c
new file mode 100644
index 00000000000..b5b2ae793f9
--- /dev/null
+++ b/source/blender/blenlib/intern/voxel.c
@@ -0,0 +1,299 @@
+/**
+ *
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * 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
+ * of the License, 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ *
+ * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
+ * All rights reserved.
+ *
+ * The Original Code is: all of this file.
+ *
+ * Contributor(s): Matt Ebb, Raul Fernandez Hernandez (Farsthary).
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+#include <math.h>
+
+#include "BLI_voxel.h"
+
+#include "BKE_utildefines.h"
+
+
+#if defined( _MSC_VER ) && !defined( __cplusplus )
+# define inline __inline
+#endif // defined( _MSC_VER ) && !defined( __cplusplus )
+
+static inline float D(float *data,  int *res, int x, int y, int z)
+{
+	CLAMP(x, 0, res[0]-1);
+	CLAMP(y, 0, res[1]-1);
+	CLAMP(z, 0, res[2]-1);
+	return data[ V_I(x, y, z, res) ];
+}
+
+/* *** nearest neighbour *** */
+/* input coordinates must be in bounding box 0.0 - 1.0 */
+float voxel_sample_nearest(float *data, int *res, float *co)
+{
+	int xi, yi, zi;
+	
+	xi = co[0] * res[0];
+	yi = co[1] * res[1];
+	zi = co[2] * res[2];
+	
+	return D(data, res, xi, yi, zi);
+}
+
+
+/* *** trilinear *** */
+/* input coordinates must be in bounding box 0.0 - 1.0 */
+
+static inline float lerp(float t, float v1, float v2) {
+	return (1.f - t) * v1 + t * v2;
+}
+
+/* trilinear interpolation - taken partly from pbrt's implementation: http://www.pbrt.org */
+float voxel_sample_trilinear(float *data, int *res, float *co)
+{
+	float voxx, voxy, voxz;
+	int vx, vy, vz;
+	float dx, dy, dz;
+	float d00, d10, d01, d11, d0, d1, d_final;
+	
+	if (!data) return 0.f;
+	
+	voxx = co[0] * res[0] - 0.5f;
+	voxy = co[1] * res[1] - 0.5f;
+	voxz = co[2] * res[2] - 0.5f;
+	
+	vx = (int)voxx; vy = (int)voxy; vz = (int)voxz;
+	
+	dx = voxx - vx; dy = voxy - vy; dz = voxz - vz;
+	
+	d00 = lerp(dx, D(data, res, vx, vy, vz), 		D(data, res, vx+1, vy, vz));
+	d10 = lerp(dx, D(data, res, vx, vy+1, vz), 		D(data, res, vx+1, vy+1, vz));
+	d01 = lerp(dx, D(data, res, vx, vy, vz+1), 		D(data, res, vx+1, vy, vz+1));
+	d11 = lerp(dx, D(data, res, vx, vy+1, vz+1), 	D(data, res, vx+1, vy+1, vz+1));
+	d0 = lerp(dy, d00, d10);
+	d1 = lerp(dy, d01, d11);
+	d_final = lerp(dz, d0, d1);
+	
+	return d_final;
+}
+
+/* *** tricubic *** */
+
+int C[64][64] = {
+{ 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{-3, 3, 0, 0, 0, 0, 0, 0,-2,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 2,-2, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{-3, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2, 0,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0,-3, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2, 0,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 9,-9,-9, 9, 0, 0, 0, 0, 6, 3,-6,-3, 0, 0, 0, 0, 6,-6, 3,-3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 2, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{-6, 6, 6,-6, 0, 0, 0, 0,-3,-3, 3, 3, 0, 0, 0, 0,-4, 4,-2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2,-2,-1,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 2, 0,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 2, 0,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{-6, 6, 6,-6, 0, 0, 0, 0,-4,-2, 4, 2, 0, 0, 0, 0,-3, 3,-3, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2,-1,-2,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 4,-4,-4, 4, 0, 0, 0, 0, 2, 2,-2,-2, 0, 0, 0, 0, 2,-2, 2,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3, 3, 0, 0, 0, 0, 0, 0,-2,-1, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2,-2, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2, 0,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2, 0,-1, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9,-9,-9, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 3,-6,-3, 0, 0, 0, 0, 6,-6, 3,-3, 0, 0, 0, 0, 4, 2, 2, 1, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-6, 6, 6,-6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3,-3, 3, 3, 0, 0, 0, 0,-4, 4,-2, 2, 0, 0, 0, 0,-2,-2,-1,-1, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-6, 6, 6,-6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-4,-2, 4, 2, 0, 0, 0, 0,-3, 3,-3, 3, 0, 0, 0, 0,-2,-1,-2,-1, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4,-4,-4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2,-2,-2, 0, 0, 0, 0, 2,-2, 2,-2, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0},
+{-3, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2, 0, 0, 0,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0,-3, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2, 0, 0, 0,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 9,-9, 0, 0,-9, 9, 0, 0, 6, 3, 0, 0,-6,-3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6,-6, 0, 0, 3,-3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 2, 0, 0, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{-6, 6, 0, 0, 6,-6, 0, 0,-3,-3, 0, 0, 3, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-4, 4, 0, 0,-2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2,-2, 0, 0,-1,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2, 0, 0, 0,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2, 0, 0, 0,-1, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9,-9, 0, 0,-9, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 3, 0, 0,-6,-3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6,-6, 0, 0, 3,-3, 0, 0, 4, 2, 0, 0, 2, 1, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-6, 6, 0, 0, 6,-6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3,-3, 0, 0, 3, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-4, 4, 0, 0,-2, 2, 0, 0,-2,-2, 0, 0,-1,-1, 0, 0},
+{ 9, 0,-9, 0,-9, 0, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 3, 0,-6, 0,-3, 0, 6, 0,-6, 0, 3, 0,-3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 2, 0, 2, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 9, 0,-9, 0,-9, 0, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 3, 0,-6, 0,-3, 0, 6, 0,-6, 0, 3, 0,-3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 2, 0, 2, 0, 1, 0},
+{-27,27,27,-27,27,-27,-27,27,-18,-9,18, 9,18, 9,-18,-9,-18,18,-9, 9,18,-18, 9,-9,-18,18,18,-18,-9, 9, 9,-9,-12,-6,-6,-3,12, 6, 6, 3,-12,-6,12, 6,-6,-3, 6, 3,-12,12,-6, 6,-6, 6,-3, 3,-8,-4,-4,-2,-4,-2,-2,-1},
+{18,-18,-18,18,-18,18,18,-18, 9, 9,-9,-9,-9,-9, 9, 9,12,-12, 6,-6,-12,12,-6, 6,12,-12,-12,12, 6,-6,-6, 6, 6, 6, 3, 3,-6,-6,-3,-3, 6, 6,-6,-6, 3, 3,-3,-3, 8,-8, 4,-4, 4,-4, 2,-2, 4, 4, 2, 2, 2, 2, 1, 1},
+{-6, 0, 6, 0, 6, 0,-6, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3, 0,-3, 0, 3, 0, 3, 0,-4, 0, 4, 0,-2, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2, 0,-2, 0,-1, 0,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0,-6, 0, 6, 0, 6, 0,-6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3, 0,-3, 0, 3, 0, 3, 0,-4, 0, 4, 0,-2, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2, 0,-2, 0,-1, 0,-1, 0},
+{18,-18,-18,18,-18,18,18,-18,12, 6,-12,-6,-12,-6,12, 6, 9,-9, 9,-9,-9, 9,-9, 9,12,-12,-12,12, 6,-6,-6, 6, 6, 3, 6, 3,-6,-3,-6,-3, 8, 4,-8,-4, 4, 2,-4,-2, 6,-6, 6,-6, 3,-3, 3,-3, 4, 2, 4, 2, 2, 1, 2, 1},
+{-12,12,12,-12,12,-12,-12,12,-6,-6, 6, 6, 6, 6,-6,-6,-6, 6,-6, 6, 6,-6, 6,-6,-8, 8, 8,-8,-4, 4, 4,-4,-3,-3,-3,-3, 3, 3, 3, 3,-4,-4, 4, 4,-2,-2, 2, 2,-4, 4,-4, 4,-2, 2,-2, 2,-2,-2,-2,-2,-1,-1,-1,-1},
+{ 2, 0, 0, 0,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{-6, 6, 0, 0, 6,-6, 0, 0,-4,-2, 0, 0, 4, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3, 3, 0, 0,-3, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2,-1, 0, 0,-2,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 4,-4, 0, 0,-4, 4, 0, 0, 2, 2, 0, 0,-2,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2,-2, 0, 0, 2,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-6, 6, 0, 0, 6,-6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-4,-2, 0, 0, 4, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-3, 3, 0, 0,-3, 3, 0, 0,-2,-1, 0, 0,-2,-1, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4,-4, 0, 0,-4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 0, 0,-2,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2,-2, 0, 0, 2,-2, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0},
+{-6, 0, 6, 0, 6, 0,-6, 0, 0, 0, 0, 0, 0, 0, 0, 0,-4, 0,-2, 0, 4, 0, 2, 0,-3, 0, 3, 0,-3, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2, 0,-1, 0,-2, 0,-1, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0,-6, 0, 6, 0, 6, 0,-6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,-4, 0,-2, 0, 4, 0, 2, 0,-3, 0, 3, 0,-3, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0,-2, 0,-1, 0,-2, 0,-1, 0},
+{18,-18,-18,18,-18,18,18,-18,12, 6,-12,-6,-12,-6,12, 6,12,-12, 6,-6,-12,12,-6, 6, 9,-9,-9, 9, 9,-9,-9, 9, 8, 4, 4, 2,-8,-4,-4,-2, 6, 3,-6,-3, 6, 3,-6,-3, 6,-6, 3,-3, 6,-6, 3,-3, 4, 2, 2, 1, 4, 2, 2, 1},
+{-12,12,12,-12,12,-12,-12,12,-6,-6, 6, 6, 6, 6,-6,-6,-8, 8,-4, 4, 8,-8, 4,-4,-6, 6, 6,-6,-6, 6, 6,-6,-4,-4,-2,-2, 4, 4, 2, 2,-3,-3, 3, 3,-3,-3, 3, 3,-4, 4,-2, 2,-4, 4,-2, 2,-2,-2,-1,-1,-2,-2,-1,-1},
+{ 4, 0,-4, 0,-4, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 2, 0,-2, 0,-2, 0, 2, 0,-2, 0, 2, 0,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+{ 0, 0, 0, 0, 0, 0, 0, 0, 4, 0,-4, 0,-4, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 2, 0,-2, 0,-2, 0, 2, 0,-2, 0, 2, 0,-2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0},
+{-12,12,12,-12,12,-12,-12,12,-8,-4, 8, 4, 8, 4,-8,-4,-6, 6,-6, 6, 6,-6, 6,-6,-6, 6, 6,-6,-6, 6, 6,-6,-4,-2,-4,-2, 4, 2, 4, 2,-4,-2, 4, 2,-4,-2, 4, 2,-3, 3,-3, 3,-3, 3,-3, 3,-2,-1,-2,-1,-2,-1,-2,-1},
+{ 8,-8,-8, 8,-8, 8, 8,-8, 4, 4,-4,-4,-4,-4, 4, 4, 4,-4, 4,-4,-4, 4,-4, 4, 4,-4,-4, 4, 4,-4,-4, 4, 2, 2, 2, 2,-2,-2,-2,-2, 2, 2,-2,-2, 2, 2,-2,-2, 2,-2, 2,-2, 2,-2, 2,-2, 1, 1, 1, 1, 1, 1, 1, 1}};
+
+static int ijk2n(int i, int j, int k) {
+	return(i+4*j+16*k);
+}
+
+static void tricubic_get_coeff_stacked(float a[64], float x[64]) {
+	int i,j;
+	for (i=0;i<64;i++) {
+		a[i]=(float)(0.0);
+		for (j=0;j<64;j++) {
+			a[i]+=C[i][j]*x[j];
+		}
+	}
+}
+
+
+
+
+static void tricubic_get_coeff(float a[64], float f[8], float dfdx[8], float dfdy[8], float dfdz[8], float d2fdxdy[8], float d2fdxdz[8], float d2fdydz[8], float d3fdxdydz[8]) {
+	int i;
+	float x[64];
+	for (i=0;i<8;i++) {
+		x[0+i]=f[i];
+		x[8+i]=dfdx[i];
+		x[16+i]=dfdy[i];
+		x[24+i]=dfdz[i];
+		x[32+i]=d2fdxdy[i];
+		x[40+i]=d2fdxdz[i];
+		x[48+i]=d2fdydz[i];
+		x[56+i]=d3fdxdydz[i];
+	}
+	tricubic_get_coeff_stacked(a,x);
+}
+
+static float tricubic_eval(float a[64], float x, float y, float z) {
+	int i,j,k;
+	float ret=(float)(0.0);
+	
+	for (i=0;i<4;i++) {
+		for (j=0;j<4;j++) {
+			for (k=0;k<4;k++) {
+				ret+=a[ijk2n(i,j,k)]*pow(x,i)*pow(y,j)*pow(z,k);
+			}
+		}
+	}
+	return(ret);
+}
+
+/* tricubic interpolation
+ * from 'libtricubic': http://www.lekien.com/~francois/software/tricubic/ 
+ * input coordinates must be in bounding box 0.0 - 1.0 */
+float voxel_sample_tricubic(float *data, int *res, float *co)
+{
+	float xx, yy, zz;
+	int xi,yi,zi;
+	int *n = res;
+	float dx,dy,dz;
+	float a[64];
+	
+	xx = co[0] * res[0] - 0.5f;
+	yy = co[1] * res[1] - 0.5f;
+	zz = co[2] * res[2] - 0.5f;
+	
+	xi = (int)xx; yi = (int)yy; zi = (int)zz;
+	
+	{
+		float fval[8]={data[V_I(xi,yi,zi,n)],data[V_I(xi+1,yi,zi,n)],data[V_I(xi,yi+1,zi,n)],data[V_I(xi+1,yi+1,zi,n)],data[V_I(xi,yi,zi+1,n)],data[V_I(xi+1,yi,zi+1,n)],data[V_I(xi,yi+1,zi+1,n)],data[V_I(xi+1,yi+1,zi+1,n)]}; 
+		
+		float dfdxval[8]={0.5f*(data[V_I(xi+1,yi,zi,n)]-data[V_I(xi-1,yi,zi,n)]),0.5f*(data[V_I(xi+2,yi,zi,n)]-data[V_I(xi,yi,zi,n)]),
+			0.5f*(data[V_I(xi+1,yi+1,zi,n)]-data[V_I(xi-1,yi+1,zi,n)]),0.5f*(data[V_I(xi+2,yi+1,zi,n)]-data[V_I(xi,yi+1,zi,n)]),
+			0.5f*(data[V_I(xi+1,yi,zi+1,n)]-data[V_I(xi-1,yi,zi+1,n)]),0.5f*(data[V_I(xi+2,yi,zi+1,n)]-data[V_I(xi,yi,zi+1,n)]),
+			0.5f*(data[V_I(xi+1,yi+1,zi+1,n)]-data[V_I(xi-1,yi+1,zi+1,n)]),
+			0.5f*(data[V_I(xi+2,yi+1,zi+1,n)]-data[V_I(xi,yi+1,zi+1,n)])};						
+		
+		float dfdyval[8]={0.5f*(data[V_I(xi,yi+1,zi,n)]-data[V_I(xi,yi-1,zi,n)]),0.5f*(data[V_I(xi+1,yi+1,zi,n)]-data[V_I(xi+1,yi-1,zi,n)]),
+			0.5f*(data[V_I(xi,yi+2,zi,n)]-data[V_I(xi,yi,zi,n)]),0.5f*(data[V_I(xi+1,yi+2,zi,n)]-data[V_I(xi+1,yi,zi,n)]),
+			0.5f*(data[V_I(xi,yi+1,zi+1,n)]-data[V_I(xi,yi-1,zi+1,n)]),0.5f*(data[V_I(xi+1,yi+1,zi+1,n)]-data[V_I(xi+1,yi-1,zi+1,n)]),
+			0.5f*(data[V_I(xi,yi+2,zi+1,n)]-data[V_I(xi,yi,zi+1,n)]),
+			0.5f*(data[V_I(xi+1,yi+2,zi+1,n)]-data[V_I(xi+1,yi,zi+1,n)])};						 
+		
+		float dfdzval[8]={0.5f*(data[V_I(xi,yi,zi+1,n)]-data[V_I(xi,yi,zi-1,n)]),0.5f*(data[V_I(xi+1,yi,zi+1,n)]-data[V_I(xi+1,yi,zi-1,n)]),
+			0.5f*(data[V_I(xi,yi+1,zi+1,n)]-data[V_I(xi,yi+1,zi-1,n)]),0.5f*(data[V_I(xi+1,yi+1,zi+1,n)]-data[V_I(xi+1,yi+1,zi-1,n)]),
+			0.5f*(data[V_I(xi,yi,zi+2,n)]-data[V_I(xi,yi,zi,n)]),0.5f*(data[V_I(xi+1,yi,zi+2,n)]-data[V_I(xi+1,yi,zi,n)]),
+			0.5f*(data[V_I(xi,yi+1,zi+2,n)]-data[V_I(xi,yi+1,zi,n)]),
+			0.5f*(data[V_I(xi+1,yi+1,zi+2,n)]-data[V_I(xi+1,yi+1,zi,n)])};						 
+		
+		float d2fdxdyval[8]={0.25*(data[V_I(xi+1,yi+1,zi,n)]-data[V_I(xi-1,yi+1,zi,n)]-data[V_I(xi+1,yi-1,zi,n)]+data[V_I(xi-1,yi-1,zi,n)]),
+			0.25*(data[V_I(xi+2,yi+1,zi,n)]-data[V_I(xi,yi+1,zi,n)]-data[V_I(xi+2,yi-1,zi,n)]+data[V_I(xi,yi-1,zi,n)]),
+			0.25*(data[V_I(xi+1,yi+2,zi,n)]-data[V_I(xi-1,yi+2,zi,n)]-data[V_I(xi+1,yi,zi,n)]+data[V_I(xi-1,yi,zi,n)]),
+			0.25*(data[V_I(xi+2,yi+2,zi,n)]-data[V_I(xi,yi+2,zi,n)]-data[V_I(xi+2,yi,zi,n)]+data[V_I(xi,yi,zi,n)]),
+			0.25*(data[V_I(xi+1,yi+1,zi+1,n)]-data[V_I(xi-1,yi+1,zi+1,n)]-data[V_I(xi+1,yi-1,zi+1,n)]+data[V_I(xi-1,yi-1,zi+1,n)]),
+			0.25*(data[V_I(xi+2,yi+1,zi+1,n)]-data[V_I(xi,yi+1,zi+1,n)]-data[V_I(xi+2,yi-1,zi+1,n)]+data[V_I(xi,yi-1,zi+1,n)]),
+			0.25*(data[V_I(xi+1,yi+2,zi+1,n)]-data[V_I(xi-1,yi+2,zi+1,n)]-data[V_I(xi+1,yi,zi+1,n)]+data[V_I(xi-1,yi,zi+1,n)]),
+			0.25*(data[V_I(xi+2,yi+2,zi+1,n)]-data[V_I(xi,yi+2,zi+1,n)]-data[V_I(xi+2,yi,zi+1,n)]+data[V_I(xi,yi,zi+1,n)])};						 
+		
+		float d2fdxdzval[8]={0.25f*(data[V_I(xi+1,yi,zi+1,n)]-data[V_I(xi-1,yi,zi+1,n)]-data[V_I(xi+1,yi,zi-1,n)]+data[V_I(xi-1,yi,zi-1,n)]),
+			0.25f*(data[V_I(xi+2,yi,zi+1,n)]-data[V_I(xi,yi,zi+1,n)]-data[V_I(xi+2,yi,zi-1,n)]+data[V_I(xi,yi,zi-1,n)]),
+			0.25f*(data[V_I(xi+1,yi+1,zi+1,n)]-data[V_I(xi-1,yi+1,zi+1,n)]-data[V_I(xi+1,yi+1,zi-1,n)]+data[V_I(xi-1,yi+1,zi-1,n)]),
+			0.25f*(data[V_I(xi+2,yi+1,zi+1,n)]-data[V_I(xi,yi+1,zi+1,n)]-data[V_I(xi+2,yi+1,zi-1,n)]+data[V_I(xi,yi+1,zi-1,n)]),
+			0.25f*(data[V_I(xi+1,yi,zi+2,n)]-data[V_I(xi-1,yi,zi+2,n)]-data[V_I(xi+1,yi,zi,n)]+data[V_I(xi-1,yi,zi,n)]),
+			0.25f*(data[V_I(xi+2,yi,zi+2,n)]-data[V_I(xi,yi,zi+2,n)]-data[V_I(xi+2,yi,zi,n)]+data[V_I(xi,yi,zi,n)]),
+			0.25f*(data[V_I(xi+1,yi+1,zi+2,n)]-data[V_I(xi-1,yi+1,zi+2,n)]-data[V_I(xi+1,yi+1,zi,n)]+data[V_I(xi-1,yi+1,zi,n)]),
+			0.25f*(data[V_I(xi+2,yi+1,zi+2,n)]-data[V_I(xi,yi+1,zi+2,n)]-data[V_I(xi+2,yi+1,zi,n)]+data[V_I(xi,yi+1,zi,n)])};
+		
+		
+		float d2fdydzval[8]={0.25f*(data[V_I(xi,yi+1,zi+1,n)]-data[V_I(xi,yi-1,zi+1,n)]-data[V_I(xi,yi+1,zi-1,n)]+data[V_I(xi,yi-1,zi-1,n)]),
+			0.25f*(data[V_I(xi+1,yi+1,zi+1,n)]-data[V_I(xi+1,yi-1,zi+1,n)]-data[V_I(xi+1,yi+1,zi-1,n)]+data[V_I(xi+1,yi-1,zi-1,n)]),
+			0.25f*(data[V_I(xi,yi+2,zi+1,n)]-data[V_I(xi,yi,zi+1,n)]-data[V_I(xi,yi+2,zi-1,n)]+data[V_I(xi,yi,zi-1,n)]),
+			0.25f*(data[V_I(xi+1,yi+2,zi+1,n)]-data[V_I(xi+1,yi,zi+1,n)]-data[V_I(xi+1,yi+2,zi-1,n)]+data[V_I(xi+1,yi,zi-1,n)]),
+			0.25f*(data[V_I(xi,yi+1,zi+2,n)]-data[V_I(xi,yi-1,zi+2,n)]-data[V_I(xi,yi+1,zi,n)]+data[V_I(xi,yi-1,zi,n)]),
+			0.25f*(data[V_I(xi+1,yi+1,zi+2,n)]-data[V_I(xi+1,yi-1,zi+2,n)]-data[V_I(xi+1,yi+1,zi,n)]+data[V_I(xi+1,yi-1,zi,n)]),
+			0.25f*(data[V_I(xi,yi+2,zi+2,n)]-data[V_I(xi,yi,zi+2,n)]-data[V_I(xi,yi+2,zi,n)]+data[V_I(xi,yi,zi,n)]),
+			0.25f*(data[V_I(xi+1,yi+2,zi+2,n)]-data[V_I(xi+1,yi,zi+2,n)]-data[V_I(xi+1,yi+2,zi,n)]+data[V_I(xi+1,yi,zi,n)])};
+		
+		
+		float d3fdxdydzval[8]={0.125f*(data[V_I(xi+1,yi+1,zi+1,n)]-data[V_I(xi-1,yi+1,zi+1,n)]-data[V_I(xi+1,yi-1,zi+1,n)]+data[V_I(xi-1,yi-1,zi+1,n)]-data[V_I(xi+1,yi+1,zi-1,n)]+data[V_I(xi-1,yi+1,zi-1,n)]+data[V_I(xi+1,yi-1,zi-1,n)]-data[V_I(xi-1,yi-1,zi-1,n)]),
+			0.125f*(data[V_I(xi+2,yi+1,zi+1,n)]-data[V_I(xi,yi+1,zi+1,n)]-data[V_I(xi+2,yi-1,zi+1,n)]+data[V_I(xi,yi-1,zi+1,n)]-data[V_I(xi+2,yi+1,zi-1,n)]+data[V_I(xi,yi+1,zi-1,n)]+data[V_I(xi+2,yi-1,zi-1,n)]-data[V_I(xi,yi-1,zi-1,n)]),
+			0.125f*(data[V_I(xi+1,yi+2,zi+1,n)]-data[V_I(xi-1,yi+2,zi+1,n)]-data[V_I(xi+1,yi,zi+1,n)]+data[V_I(xi-1,yi,zi+1,n)]-data[V_I(xi+1,yi+2,zi-1,n)]+data[V_I(xi-1,yi+2,zi-1,n)]+data[V_I(xi+1,yi,zi-1,n)]-data[V_I(xi-1,yi,zi-1,n)]),
+			0.125f*(data[V_I(xi+2,yi+2,zi+1,n)]-data[V_I(xi,yi+2,zi+1,n)]-data[V_I(xi+2,yi,zi+1,n)]+data[V_I(xi,yi,zi+1,n)]-data[V_I(xi+2,yi+2,zi-1,n)]+data[V_I(xi,yi+2,zi-1,n)]+data[V_I(xi+2,yi,zi-1,n)]-data[V_I(xi,yi,zi-1,n)]),
+			0.125f*(data[V_I(xi+1,yi+1,zi+2,n)]-data[V_I(xi-1,yi+1,zi+2,n)]-data[V_I(xi+1,yi-1,zi+2,n)]+data[V_I(xi-1,yi-1,zi+2,n)]-data[V_I(xi+1,yi+1,zi,n)]+data[V_I(xi-1,yi+1,zi,n)]+data[V_I(xi+1,yi-1,zi,n)]-data[V_I(xi-1,yi-1,zi,n)]),
+			0.125f*(data[V_I(xi+2,yi+1,zi+2,n)]-data[V_I(xi,yi+1,zi+2,n)]-data[V_I(xi+2,yi-1,zi+2,n)]+data[V_I(xi,yi-1,zi+2,n)]-data[V_I(xi+2,yi+1,zi,n)]+data[V_I(xi,yi+1,zi,n)]+data[V_I(xi+2,yi-1,zi,n)]-data[V_I(xi,yi-1,zi,n)]),
+			0.125f*(data[V_I(xi+1,yi+2,zi+2,n)]-data[V_I(xi-1,yi+2,zi+2,n)]-data[V_I(xi+1,yi,zi+2,n)]+data[V_I(xi-1,yi,zi+2,n)]-data[V_I(xi+1,yi+2,zi,n)]+data[V_I(xi-1,yi+2,zi,n)]+data[V_I(xi+1,yi,zi,n)]-data[V_I(xi-1,yi,zi,n)]),
+			0.125f*(data[V_I(xi+2,yi+2,zi+2,n)]-data[V_I(xi,yi+2,zi+2,n)]-data[V_I(xi+2,yi,zi+2,n)]+data[V_I(xi,yi,zi+2,n)]-data[V_I(xi+2,yi+2,zi,n)]+data[V_I(xi,yi+2,zi,n)]+data[V_I(xi+2,yi,zi,n)]-data[V_I(xi,yi,zi,n)])};
+		
+		
+		tricubic_get_coeff(a,fval,dfdxval,dfdyval,dfdzval,d2fdxdyval,d2fdxdzval,d2fdydzval,d3fdxdydzval);
+	}
+	
+	dx = xx-xi;
+	dy = yy-yi;
+	dz = zz-zi;
+	
+	return tricubic_eval(a,dx,dy,dz);
+	
+}
+