From c2293062f35b8c2d7c424c48baf42173eac617b5 Mon Sep 17 00:00:00 2001
From: Trammell Hudson <hudson@trmm.net>
Date: Sat, 14 Feb 2015 20:03:39 -0500
Subject: [PATCH] generate two planes, separated by thickness

---
 corners.c | 37 +++++++++++++++++++++++++++++++------
 1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/corners.c b/corners.c
index a81be92..f57923c 100644
--- a/corners.c
+++ b/corners.c
@@ -20,6 +20,7 @@ main(void)
 	stl_3d_t * const stl = stl_3d_parse(STDIN_FILENO);
 	if (!stl)
 		return EXIT_FAILURE;
+	const double thickness = 3;
 
 	// for each vertex, find the coplanar triangles
 	// \todo: do coplanar bits
@@ -37,17 +38,40 @@ main(void)
 		for (int j = 0 ; j < v->num_face; j++)
 		{
 			const stl_face_t * const f = v->face[j];
-			v3_t v1 = v3_sub(f->vertex[0]->p, origin);
-			v3_t v2 = v3_sub(f->vertex[1]->p, origin);
-			v3_t v3 = v3_sub(f->vertex[2]->p, origin);
+			v3_t v0 = v3_sub(f->vertex[0]->p, origin);
+			v3_t v1 = v3_sub(f->vertex[1]->p, origin);
+			v3_t v2 = v3_sub(f->vertex[2]->p, origin);
+			v3_t n;
+
+			if (v->face_num[j] == 0)
+				n = v3_cross(v1, v2);
+			else
+			if (v->face_num[j] == 1)
+				n = v3_cross(v2, v0);
+			else
+			if (v->face_num[j] == 2)
+				n = v3_cross(v0, v1);
+
+			n = v3_scale(n, thickness/v3_mag(n)/2);
+
+			v0 = v3_add(v0, n);
+			v1 = v3_add(v1, n);
+			v2 = v3_add(v2, n);
+			v3_t v3 = v3_sub(v0, n);
+			v3_t v4 = v3_sub(v1, n);
+			v3_t v5 = v3_sub(v2, n);
 
 			printf("%%polyhedron(\n"
 				"points=[\n"
 				"[%f,%f,%f],[%f,%f,%f],[%f,%f,%f],\n"
-				"], faces = [[0,1,2]]);\n",
+				"[%f,%f,%f],[%f,%f,%f],[%f,%f,%f],\n"
+				"], faces = [[0,1,2], [3,4,5]]);\n",
+				v0.p[0], v0.p[1], v0.p[2],
 				v1.p[0], v1.p[1], v1.p[2],
 				v2.p[0], v2.p[1], v2.p[2],
-				v3.p[0], v3.p[1], v3.p[2]
+				v3.p[0], v3.p[1], v3.p[2],
+				v4.p[0], v4.p[1], v4.p[2],
+				v5.p[0], v5.p[1], v5.p[2]
 			);
 				
 /*
@@ -58,10 +82,11 @@ main(void)
 				f->face[2] ? f->face[2] - stl->face : -1, f->angle[2]
 			);
 */
+			break; // only do one right now
 		}
 
 		printf("}\n");
-		break;
+		break; // only do one right now
 	}
 
 	return 0;