svg faces generator

Makefile

@@ -10,11 +10,12 @@ CFLAGS = \
 LDLIBS = \
 	-lm \
 
-all: unfold wireframe corners
+all: unfold wireframe corners faces
 
 unfold: unfold.o
 wireframe: wireframe.o
 corners: corners.o stl_3d.o
+faces: faces.o stl_3d.o
 
 clean:
 	$(RM) *.o

faces.c

@@ -0,0 +1,139 @@
+/** \file
+ * Generate an svg file with the polygonal faces.
+ *
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <math.h>
+#include <err.h>
+#include <assert.h>
+#include "v3.h"
+#include "stl_3d.h"
+
+static const char * stroke_string
+	= "stroke=\"#FF0000\" stroke-width=\"1px\" fill=\"none\"";
+
+typedef struct
+{
+	v3_t origin;
+	v3_t x;
+	v3_t y;
+	v3_t z;
+} refframe_t;
+
+
+static void
+v3_project(
+	const refframe_t * const ref,
+	const v3_t p_in,
+	double * const x_out,
+	double * const y_out
+)
+{
+	v3_t p = v3_sub(p_in, ref->origin);
+
+	double x = ref->x.p[0]*p.p[0] + ref->x.p[1]*p.p[1] + ref->x.p[2]*p.p[2];
+	double y = ref->y.p[0]*p.p[0] + ref->y.p[1]*p.p[1] + ref->y.p[2]*p.p[2];
+	double z = ref->z.p[0]*p.p[0] + ref->z.p[1]*p.p[1] + ref->z.p[2]*p.p[2];
+
+	fprintf(stderr, "%f,%f,%f\n", x, y, z);
+
+	*x_out = x;
+	*y_out = y;
+}
+
+
+static void
+svg_line(
+	const refframe_t * const ref,
+	const v3_t p1,
+	const v3_t p2
+)
+{
+	// project p1 and p2 into the plane
+	double x1, y1, x2, y2;
+
+	v3_project(ref, p1, &x1, &y1);
+	v3_project(ref, p2, &x2, &y2);
+
+	printf("<line x1=\"%f\" y1=\"%f\" x2=\"%f\" y2=\"%f\" %s/>\n",
+		x1, y1,
+		x2, y2,
+		stroke_string
+	);
+}
+
+
+void
+draw_face(
+	const stl_3d_t * const stl,
+	const stl_face_t * const f,
+	int * const face_used,
+	const refframe_t * const ref
+)
+{
+	if (face_used[f - stl->face]++)
+		return;
+
+	for (int i = 0 ; i < 3 ; i++)
+	{
+		if (!f->face[i] || f->angle[i] != 0)
+		{
+			// not coplanar (or missing?)
+			svg_line(ref, f->vertex[i]->p, f->vertex[(i+1)%3]->p);
+		} else {
+			// coplanar, recurse
+			draw_face(stl, f->face[i], face_used, ref);
+		}
+	}
+}
+
+
+int
+main(void)
+{
+	stl_3d_t * const stl = stl_3d_parse(STDIN_FILENO);
+	if (!stl)
+		return EXIT_FAILURE;
+	const double inset = 8;
+	const double hole = 3;
+
+	int * const face_used = calloc(sizeof(*face_used), stl->num_face);
+
+	// for each vertex, find the coplanar triangles
+	// \todo: do coplanar bits
+	printf("<svg xmlns=\"http://www.w3.org/2000/svg\">\n");
+	printf("<g transform=\"scale(3.543307)\"><!-- scale to mm -->\n");
+
+
+	for(int i = 0 ; i < stl->num_face ; i++)
+	{
+		if (face_used[i])
+			continue;
+
+		const stl_face_t * const f = &stl->face[i];
+
+		// generate a refernce frame based on this face
+		refframe_t ref = {
+			.origin = f->vertex[0]->p,
+		};
+
+		const v3_t dx = v3_norm(v3_sub(f->vertex[1]->p, ref.origin));
+		const v3_t dy = v3_norm(v3_sub(f->vertex[2]->p, ref.origin));
+
+		ref.x = dx;
+		ref.z = v3_norm(v3_cross(dx, dy));
+		ref.y = v3_norm(v3_cross(ref.x, ref.z));
+
+		printf("<!-- face %d --><g>\n", i);
+		draw_face(stl, f, face_used, &ref);
+		printf("</g>\n");
+	}
+
+	printf("</g></svg>\n");
+
+	return 0;
+}