Sanitize POV-Ray output (in progress)

- solidify/main.pov: set up a more traditional view than POV-Ray's "camera"
  model
- solidify/main.pov: mark the coordinate axes with colored balls
- solidify/main.pov: make the part semi-transparent so that we can see the
  coordinate axes
- solidify/solid.c (povray_face, povray): moved dumping a face from
  povray() to povray_face()
- solidify/solid.c (povray_face): scale the height field to its real size
- solidify/solid.c (povray_face): rotate the face such that height is Z
- solidify/solid.c (povray_face): translate the face such that its center
  is at the origin

solidify/main.pov

@@ -1,25 +1,51 @@
 #include "colors.inc"
 #include "batcvr.inc"
 
+/*
+ * POV-Ray defaults to a "camera" coordinate system that can be confusing.
+ * We use a traditional mathematical/engineering view, with a view from
+ * X-/Y-/Z+ into the X/Y plane.
+ */
+
 camera {
-    location < 2, 2, 3>
-    look_at < 0, 0, 0>
+    location <-30, -80, 40>
+    look_at <20, 20, 0>
+    sky z
+    right -4/3*x
 }
 
 background { color White }
 
 light_source {
-    < 4, 7, 4>
+    <-200, -300, 200>
     color White
 }
 
+/*
+ * Mark the coordinate axes:
+ * - a red unit sphere at the center
+ * - three green spheres at x = 10*i
+ * - two blue spheres at y = 10*i
+ * - one yellow sphere at z = 10
+ */
+
+sphere { < 0,  0,  0>, 1 pigment { color Red } }
+sphere { <10,  0,  0>, 1 pigment { color Green } }
+sphere { <20,  0,  0>, 1 pigment { color Green } }
+sphere { <30,  0,  0>, 1 pigment { color Green } }
+sphere { < 0, 10,  0>, 1 pigment { color Blue } }
+sphere { < 0, 20,  0>, 1 pigment { color Blue } }
+sphere { < 0,  0, 10>, 1 pigment { color Yellow } }
+
+#declare Finish = finish {
+    brilliance 2
+    phong 0.8
+    phong_size 100
+    metallic
+}
+
 union {
     Part_batcvr
-    pigment { rgb <0.9, 0.9, 0.9> }
-    finish {
-        brilliance 2
-        phong 0.8
-        phong_size 100
-        metallic
-    }
+    pigment { rgbf <0.9, 0.9, 0.9, 0.5> }
+    finish { Finish }
 }

solidify/solid.c

@@ -63,6 +63,35 @@ static void sanitize(const char *s, char *res)
 }
 
 
+/*
+ * For now, we put the part such that its x/y/z center is at the origin.
+ * Later, we will also have to consider the changes the user made and the
+ * relation with the opposing face.
+ */
+
+static void povray_face(const struct face *f, const char *side,
+    const char *prefix)
+{
+	int sz = f->a->max_z-f->a->min_z;
+
+	/*
+	 * 1/65535 = 0.000015..., so we set the water level a bit lower, e.g.,
+	 * to 0.0001
+	 */
+	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}\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, -sz*f->z_step/2);
+}
+
+
 void povray(const char *name, const struct solid *s)
 {
 	struct matrix m;
@@ -77,15 +106,9 @@ void povray(const char *name, const struct solid *s)
 	sprintf(tmp, "%s-bot.pgm", name);
 	height_field(tmp, s->b, &m);
 
-	/*
-	 * 1/65535 = 0.000015..., so we set the water level a bit lower, e.g.,
-	 * to 0.0001
-	 */
 	sanitize(name, tmp);
-	printf(
-"#declare Part_%s =\n"
-"    intersection {\n"
-"        height_field { pgm \"%s-top.pgm\" water_level 0.00001 smooth }\n"
-"        height_field { pgm \"%s-bot.pgm\" water_level 0.00001 smooth }\n"
-"    }\n", tmp, name, name);
+	printf("#declare Part_%s =\n    intersection {\n", tmp);
+	povray_face(s->a, "top", name);
+	povray_face(s->b, "bot", name);
+	printf("    }\n");
 }