Added remaining transformations to POV-Ray output. Added example. Cleaned up

main.pov

- solidify/povray.c (povray_face): added inclination of the z0 plane
- solidify/povray.c (povray_face): added overlap transform (rotation and
  shift)
- solidify/povray.c (povray_face): added comments to all the POV-Ray
  commands
- solidify/batcvr.sfy: battery cover example (almost looks good)
- solidify/main.pov: added second light source slightly below the xy plane
- solidify/main.pov: use "object" instead of "union" to place the part
- solidify/main.pov: make material less transparent (50% -> 20%)
- solidify/main.pov: added second battery cover, showing edge and bottom

solidify/batcvr.sfy

@@ -0,0 +1,7 @@
+http://projects.qi-hardware.com/index.php/p/ben-scans/source/tree/master/data/csv/ben-batcvr-outside-100um.txt.bz2
+http://projects.qi-hardware.com/index.php/p/ben-scans/source/tree/master/data/csv/ben-batcvr-inside-100um.txt.bz2
+1.16
+8.925 -0.0559506 2.17492
+-1.20855 -0.217572 0.230146
+8.575 -0.01507 0.548847
+-0 0 0

solidify/main.pov

@@ -21,6 +21,11 @@ light_source {
     color White
 }
 
+light_source {
+    <-100, -500, -10>
+    color White
+}
+
 /*
  * Mark the coordinate axes:
  * - a red unit sphere at the center
@@ -44,8 +49,16 @@ sphere { < 0,  0, 10>, 1 pigment { color Yellow } }
     metallic
 }
 
-union {
+object {
     Part_batcvr
-    pigment { rgbf <0.9, 0.9, 0.9, 0.5> }
+    pigment { rgbf <0.9, 0.9, 0.9, 0.2> }
     finish { Finish }
 }
+
+object {
+    Part_batcvr
+    pigment { rgbf <1, 0.8, 0.8, 0.2> }
+    finish { Finish }
+    translate <0, 0, 25>
+    rotate <0, 20, 80>
+}

solidify/povray.c

@@ -14,6 +14,7 @@
 #include <stdint.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <math.h>
 
 #include "face.h"
 #include "solid.h"
@@ -73,27 +74,39 @@ static void povray_face(const struct face *f, const char *side,
     const char *prefix, int flip, double dist)
 {
 	int sz = f->a->max_z-f->a->min_z;
+	double a;
 
 	/*
 	 * 1/65535 = 0.000015..., so we set the water level a bit lower, e.g.,
 	 * to 0.0001
 	 */
+	a = asin(-f->m.a[0][1])/M_PI*180;
+        if (f->m.a[0][0] < 0)
+                a = 180-a;
 	printf(
 "\theight_field {\n"
 "\t    pgm \"%s-%s.pgm\"\n"
 "\t    water_level 0.00001\n"
 "\t    smooth\n"
-"\t    scale <%g, %g, %g>\n"
-"\t    rotate <90, 0, 0>\n"
-"\t    translate <%g, %g, %g>\n"
-"\t    translate <0, 0, %g>\n"
+"\t    scale <%g, %g, %g>	/* scale from unit cube to real size */\n"
+"\t    rotate <90, 0, 0>	/* swap Y/Z axis */\n"
+"\t    translate <%g, %g, 0>	/* move to X/Y center */\n"
+"\t    rotate <%g, %g, 0>	/* z0 plane tilt */\n"
+"\t    translate <0, 0, %g>	/* min_z offset */\n"
+"\t    translate <0, 0, %g>	/* z0 plane offset */\n"
+"\t    rotate <0, 0, %g>	/* overlay - rotation */\n"
+"\t    translate <%g, %g, 0>	/* overlay - shift */\n"
 "%s"	/* flip bottom face */
-"\t    translate <0, 0, %g>\n"
+"\t    translate <0, 0, %g>	/* half the distance between faces */\n"
 "\t}\n", prefix, side,
     f->sx*f->x_step, sz*f->z_step, f->sy*f->y_step,
-    -f->sx*f->x_step/2, f->sy*f->y_step/2, f->a->min_z*f->z_step,
+    -f->sx*f->x_step/2, f->sy*f->y_step/2,
+    -atan(f->fy)/M_PI*180, -atan(f->fx)/M_PI*180,
+    f->a->min_z*f->z_step,
     -f->z_ref*f->z_step,
-    flip ? "\t    rotate <180, 0, 0>\n" : "",
+    a,
+    f->m.b[0]*f->x_step, f->m.b[1]*f->y_step,
+    flip ? "\t    rotate <0, 180, 0>\t/* flip bottom face */\n" : "",
     dist*f->z_step);
 }