papercraft/corners.c
2015-02-14 17:32:58 -05:00

339 lines
6.4 KiB
C

/** \file
* Generate an OpenSCAD with connectors for each face.
*
*/
#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"
static int debug = 0;
static int draw_labels = 0;
typedef struct
{
char header[80];
uint32_t num_triangles;
} __attribute__((__packed__))
stl_header_t;
typedef struct
{
v3_t normal;
v3_t p[3];
uint16_t attr;
} __attribute__((__packed__))
stl_face_t;
#define MAX_VERTEX 64
typedef struct stl_vertex stl_vertex_t;
struct stl_vertex
{
v3_t p;
int num_edges;
stl_vertex_t * edges[MAX_VERTEX];
};
/* Returns 1 for ever edge in f1 that is shared with f2.
*/
int
coplanar_check(
const stl_face_t * const f1,
const stl_face_t * const f2
)
{
// Verify that there are three matching points
int match[3] = {0,0,0};
for (int i = 0 ; i < 3 ; i++)
{
for (int j = 0 ; j < 3 ; j++)
if (v3_eq(&f1->p[i], &f2->p[j]))
match[i] = 1;
}
uint8_t mask = 0;
if (match[0] && match[1])
mask = 1;
if (match[1] && match[2])
mask = 2;
if (match[2] && match[0])
mask = 4;
if (debug)
fprintf(stderr, "%p %p: %d %d %d\n",
f1,
f2,
match[0], match[1], match[2]
);
// otherwise they do not share enough points
if (mask == 0)
return 0;
#if 0
// find the four distinct points
v3_t x1 = f1->p[0];
v3_t x2 = f1->p[1];
v3_t x3 = f1->p[2];
v3_t x4;
for (int i = 0 ; i < 3 ; i++)
{
x4 = f2->p[i];
if (v3_eq(&x1, &x4))
continue;
if (v3_eq(&x2, &x4))
continue;
if (v3_eq(&x3, &x4))
continue;
break;
}
// (x3-x1) . ((x2-x1) X (x4-x3)) == 0
v3_t dx31 = v3_sub(x3, x1);
v3_t dx21 = v3_sub(x2, x1);
v3_t dx43 = v3_sub(x4, x3);
v3_t cross = v3_cross(dx21, dx43);
float dot = v3_dot(dx31, cross);
if (debug)
fprintf(stderr, "dot %f:\n %f,%f,%f\n %f,%f,%f\n %f,%f,%f\n %f,%f,%f\n",
dot,
x1.p[0], x1.p[1], x1.p[2],
x2.p[0], x2.p[1], x2.p[2],
x3.p[0], x3.p[1], x3.p[2],
x4.p[0], x4.p[1], x4.p[2]
);
int check = -EPS < dot && dot < +EPS;
// if the dot product is not close enough to zero, they
// are not coplanar.
if (!check)
return 0;
// coplanar! return the shared edge mask
return mask;
#else
// if the normals are close enough, then it is coplanner
if (v3_eq(&f1->normal, &f2->normal))
return mask;
else
return 0;
#endif
}
static inline float
sign(
const float x
)
{
if (x < 0)
return -1;
if (x > 0)
return +1;
return 0;
}
/**
* Add a vector to the list of edges if it is not already present
* and if it is not coplanar with other ones.
* Note that if it is coplanar, but "outside" the other edges then it
* will replace the inside one.
*/
void
stl_edge_insert(
stl_vertex_t * const v1,
stl_vertex_t * const v2
)
{
for (int i = 0 ; i < v1->num_edges ; i++)
{
// if v2 already exists in the edges, discard it
if (v1->edges[i] == v2)
return;
}
// if we reach this point, we need to insert the edge
if (debug)
fprintf(stderr, "%p: edge %d -> %p\n",
v1,
v1->num_edges,
v2
);
v1->edges[v1->num_edges++] = v2;
}
/** Find or create a vertex */
stl_vertex_t *
stl_vertex_find(
stl_vertex_t ** const vertices,
int * num_vertex_ptr,
const v3_t * const p
)
{
const int num_vertex = *num_vertex_ptr;
for (int x = 0 ; x < num_vertex ; x++)
{
stl_vertex_t * const v = vertices[x];
if (v3_eq(&v->p, p))
return v;
}
if (debug)
fprintf(stderr, "%d: %f,%f,%f\n",
num_vertex,
p->p[0],
p->p[1],
p->p[2]
);
stl_vertex_t * const v = vertices[(*num_vertex_ptr)++] = calloc(1, sizeof(*v));
v->p = *p;
return v;
}
int main(void)
{
const size_t max_len = 1 << 20;
uint8_t * const buf = calloc(max_len, 1);
ssize_t rc = read(0, buf, max_len);
if (rc == -1)
return EXIT_FAILURE;
const stl_header_t * const hdr = (const void*) buf;
const stl_face_t * const stl_faces = (const void*)(hdr+1);
const int num_triangles = hdr->num_triangles;
const float thick = 7.8;
const int do_square = 1;
fprintf(stderr, "header: '%s'\n", hdr->header);
fprintf(stderr, "num: %d\n", num_triangles);
// generate the unique list of vertices and their
// correponding edges
stl_vertex_t ** const vertices = calloc(3*num_triangles, sizeof(*vertices));
int num_vertex = 0;
for(int i = 0 ; i < num_triangles ; i++)
{
if (debug) fprintf(stderr, "---------- triangle %d (%d)\n", i, num_vertex);
stl_vertex_t * vp[3] = {};
for (int j = 0 ; j < 3 ; j++)
{
const v3_t * const p = &stl_faces[i].p[j];
vp[j] = stl_vertex_find(vertices, &num_vertex, p);
}
// walk all of other triangles to figure out if
// any of the triangles are coplanar and have shared
// edges.
uint8_t coplanar_mask = 0;
for (int j = 0 ; j < num_triangles ; j++)
{
if (j == i)
continue;
if (debug)
fprintf(stderr, "%d: check %d -> %d\n", num_vertex, i, j);
coplanar_mask |= coplanar_check(
&stl_faces[i], &stl_faces[j]);
}
if (debug)
fprintf(stderr, "mask %d\n", coplanar_mask);
// all three vertices are mapped; generate the
// connections
for (int j = 0 ; j < 3 ; j++)
{
stl_vertex_t * const v = vp[j];
// if the edge from j to j+1 is not coplanar,
// add it to the list
if ((coplanar_mask & (1 << j)) == 0)
{
if (debug)
fprintf(stderr, "%p: %d insert\n", v, j);
stl_edge_insert(v, vp[(j+1) % 3]);
}
}
}
fprintf(stderr, "%d unique vertices\n", num_vertex);
printf("thick=%f;\n"
"module connector(len) {\n"
" render() difference() {\n"
" cylinder(r=thick/2+2, h=2*thick);\n"
//" translate([0,0,len/2+2]) cube([thick,thick,2*thick]);\n"
" translate([0,0,thick/2+2]) cylinder(r=thick/2, h=2*thick);\n"
" }\n"
//" %%translate([0,0,len*0.48/2]) cube([thick,thick,len*0.48], center=true);\n"
" %%translate([0,0,0]) cylinder(r=thick/2, h=len*0.48);\n"
"}\n",
thick
);
for (int i = 0 ; i < num_vertex ; i++)
{
stl_vertex_t * const v = vertices[i];
printf("translate([%f,%f,%f]) {\n",
v->p.p[0],
v->p.p[1],
v->p.p[2]
);
printf("sphere(r=%f); // %d %p\n", thick/2+2, i, v);
for (int j = 0 ; j < v->num_edges ; j++)
{
stl_vertex_t * const v2 = v->edges[j];
const v3_t d = v3_sub(v2->p, v->p);
const float len = v3_len(&v2->p, &v->p);
const float b = acos(d.p[2] / len) * 180/M_PI;
const float c = d.p[0] == 0 ? sign(d.p[1]) * 90 : atan2(d.p[1], d.p[0]) * 180/M_PI;
//
printf("rotate([0,%f,%f]) ", b, c);
if (do_square)
printf("connector(%f);\n", len);
else
printf(" cylinder(r=1, h=%f); // %p\n",
len*.45,
v2
);
}
printf("}\n");
}
return 0;
}