271 lines
4.6 KiB
C
271 lines
4.6 KiB
C
/*
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* slice.c - Generate slices
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*
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* Written 2015 by Werner Almesberger
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* Copyright 2015 by Werner Almesberger
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <stdbool.h>
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#include <math.h>
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#include <glib.h>
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#include "util.h"
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#include "stl.h"
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#include "slice.h"
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struct facet {
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struct v a, b, c;
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struct facet *next;
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};
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struct z {
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float z;
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};
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static GTree *tree;
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static struct facet *facets = NULL;
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/* ----- Bounding box ------------------------------------------------------ */
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static bool first = 1;
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static float min_x, max_x, min_y, max_y;
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static void bbox(float x, float y)
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{
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if (first) {
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min_x = max_x = x;
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min_y = max_y = y;
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first = 0;
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} else {
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if (x < min_x)
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min_x = x;
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if (y < min_y)
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min_y = y;
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if (x > max_x)
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max_x = x;
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if (y > max_y)
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max_y = y;
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}
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}
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/* ----- Data collection --------------------------------------------------- */
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static inline bool eq(float a, float b)
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{
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return fabsf(a - b) < 1e-5;
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}
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static void mark_z(float z)
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{
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struct z *e;
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e = g_tree_lookup(tree, &z);
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if (e)
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return;
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e = alloc_type(struct z);
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e->z = z;
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g_tree_insert(tree, &e->z, e);
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}
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static void add(const struct v *a, const struct v *b, const struct v *c)
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{
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float cross;
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struct facet *f;
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cross = (b->x - a->x) * (c->y - a->y) - (b->y - a->y) * (c->x - a->x);
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if (!eq(cross, 0)) {
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fprintf(stderr,
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"inclined facet\n\t%f %f %f\n\t%f %f %f\n\t%f %f %f\n",
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a->x, a->y, a->z, b->x, b->y, b->z, c->x, c->y, c->z);
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exit(1);
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}
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bbox(a->x, a->y);
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bbox(b->x, b->y);
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bbox(c->x, c->y);
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f = alloc_type(struct facet);
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f->a = *a;
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f->b = *b;
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f->c = *c;
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f->next = facets;
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facets = f;
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}
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void slice(struct v f[3])
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{
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bool ab = eq(f[0].z, f[1].z);
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bool bc = eq(f[1].z, f[2].z);
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if (ab && bc) {
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mark_z(f[0].z);
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return;
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}
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add(f + 0, f + 1, f + 2);
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}
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/* ----- Insert intermediate layers ---------------------------------------- */
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struct ctx {
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float z_step;
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bool first;
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float z0; /* only defined if !first */
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bool more; /* returned due to having made changes */
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};
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static gboolean check_z(gpointer key, gpointer value, gpointer data)
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{
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const struct z *z = value;
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struct ctx *ctx = data;
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float d;
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int n, i;
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if (ctx->first) {
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ctx->first = 0;
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ctx->z0 = z->z;
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return 0;
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}
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d = z->z - ctx->z0;
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if (d <= ctx->z_step) {
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ctx->z0 = z->z;
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return 0;
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}
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n = (d / ctx->z_step) + 1;
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for (i = 1; i < n; i++)
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mark_z(ctx->z0 + d / n * i);
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ctx->more = 1;
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return 1;
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}
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void slice_intermediate(float z_step)
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{
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struct ctx ctx = {
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.z_step = z_step,
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};
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do {
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ctx.first = 1;
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ctx.more = 0;
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g_tree_foreach(tree, check_z, &ctx);
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}
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while (ctx.more);
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}
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/* ----- Dumping ----------------------------------------------------------- */
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static bool cut(const struct v *a, const struct v *b, float z, struct v *res)
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{
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float dx, dy, dz;
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float f;
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if (a->z > b->z)
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return cut(b, a, z, res);
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if (eq(a->z, b->z))
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return 0;
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if (a->z > z || b->z < z || eq(b->z, z))
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return 0;
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dx = b->x - a->x;
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dy = b->y - a->y;
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dz = b->z - a->z;
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f = (z - a->z) / dz;
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res->x = f * dx + a->x;
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res->y = f * dy + a->y;
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res->z = z;
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return 1;
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}
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static gboolean dump_layer(gpointer key, gpointer value, gpointer data)
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{
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const struct z *z = value;
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const struct facet *f;
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struct v p1, p2;
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for (f = facets; f; f = f->next) {
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if (cut(&f->a, &f->b, z->z, &p1)) {
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if (!cut(&f->a, &f->c, z->z, &p2) &&
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!cut(&f->b, &f->c, z->z, &p2))
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continue;
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} else if (!cut(&f->a, &f->c, z->z, &p1) ||
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!cut(&f->b, &f->c, z->z, &p2)) {
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continue;
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}
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printf("%f %f %f\n%f %f %f\n\n\n",
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p1.x, p1.y, z->z, p2.x, p2.y, z->z);
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}
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return 0;
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}
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static gboolean dump_box(gpointer key, gpointer value, gpointer data)
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{
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const struct z *z = value;
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float box = *(float *) data;
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printf("%f %f %f\n%f %f %f\n%f %f %f\n%f %f %f\n%f %f %f\n\n\n",
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min_x - box, min_y - box, z->z,
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max_x + box, min_y - box, z->z,
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max_x + box, max_y + box, z->z,
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min_x - box, max_y + box, z->z,
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min_x - box, min_y - box, z->z);
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return 0;
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}
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void slice_dump(float box)
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{
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g_tree_foreach(tree, dump_layer, NULL);
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if (box && !first)
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g_tree_foreach(tree, dump_box, &box);
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}
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/* ----- Initialization ---------------------------------------------------- */
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static gint comp(gconstpointer a, gconstpointer b)
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{
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const float *za = a;
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const float *zb = b;
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return eq(*za, *zb) ? 0 : *za < *zb ? -1 : 1;
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}
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void slice_init(void)
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{
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tree = g_tree_new(comp);
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}
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