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-rw-r--r--src/glu/mesa/tesselat.c407
1 files changed, 407 insertions, 0 deletions
diff --git a/src/glu/mesa/tesselat.c b/src/glu/mesa/tesselat.c
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+++ b/src/glu/mesa/tesselat.c
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+/* $Id: tesselat.c,v 1.3 2000/07/11 14:11:04 brianp Exp $ */
+
+/*
+ * Mesa 3-D graphics library
+ * Version: 3.3
+ * Copyright (C) 1995-2000 Brian Paul
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the Free
+ * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+
+/*
+ * This file is part of the polygon tesselation code contributed by
+ * Bogdan Sikorski
+ */
+
+
+#ifdef PC_HEADER
+#include "all.h"
+#else
+#include <stdlib.h>
+#include <math.h>
+#include "tess.h"
+#endif
+
+
+
+static GLboolean edge_flag;
+
+static void emit_triangle(GLUtriangulatorObj *, tess_vertex *,
+ tess_vertex *, tess_vertex *);
+
+static void emit_triangle_with_edge_flag(GLUtriangulatorObj *,
+ tess_vertex *, GLboolean,
+ tess_vertex *, GLboolean,
+ tess_vertex *, GLboolean);
+
+static GLdouble
+twice_the_triangle_area(tess_vertex * va, tess_vertex * vb, tess_vertex * vc)
+{
+ return (vb->x - va->x) * (vc->y - va->y) - (vb->y - va->y) * (vc->x -
+ va->x);
+}
+
+static GLboolean
+left(GLdouble A, GLdouble B, GLdouble C, GLdouble x, GLdouble y)
+{
+ if (A * x + B * y + C > -EPSILON)
+ return GL_TRUE;
+ else
+ return GL_FALSE;
+}
+
+static GLboolean
+right(GLdouble A, GLdouble B, GLdouble C, GLdouble x, GLdouble y)
+{
+ if (A * x + B * y + C < EPSILON)
+ return GL_TRUE;
+ else
+ return GL_FALSE;
+}
+
+static GLint
+convex_ccw(tess_vertex * va,
+ tess_vertex * vb, tess_vertex * vc, GLUtriangulatorObj * tobj)
+{
+ GLdouble d;
+
+ d = twice_the_triangle_area(va, vb, vc);
+
+ if (d > EPSILON) {
+ return 1;
+ }
+ else if (d < -EPSILON) {
+ return 0;
+ }
+ else {
+ return -1;
+ }
+}
+
+static GLint
+convex_cw(tess_vertex * va,
+ tess_vertex * vb, tess_vertex * vc, GLUtriangulatorObj * tobj)
+{
+ GLdouble d;
+
+ d = twice_the_triangle_area(va, vb, vc);
+
+ if (d < -EPSILON) {
+ return 1;
+ }
+ else if (d > EPSILON) {
+ return 0;
+ }
+ else {
+ return -1;
+ }
+}
+
+static GLboolean
+diagonal_ccw(tess_vertex * va,
+ tess_vertex * vb,
+ GLUtriangulatorObj * tobj, tess_contour * contour)
+{
+ tess_vertex *vc = va->next, *vertex, *shadow_vertex;
+ struct
+ {
+ GLdouble A, B, C;
+ }
+ ac, cb, ba;
+ GLdouble x, y;
+
+ GLint res = convex_ccw(va, vc, vb, tobj);
+ if (res == 0)
+ return GL_FALSE;
+ if (res == -1)
+ return GL_TRUE;
+
+ ba.A = vb->y - va->y;
+ ba.B = va->x - vb->x;
+ ba.C = -ba.A * va->x - ba.B * va->y;
+ ac.A = va->y - vc->y;
+ ac.B = vc->x - va->x;
+ ac.C = -ac.A * vc->x - ac.B * vc->y;
+ cb.A = vc->y - vb->y;
+ cb.B = vb->x - vc->x;
+ cb.C = -cb.A * vb->x - cb.B * vb->y;
+ for (vertex = vb->next; vertex != va; vertex = vertex->next) {
+ shadow_vertex = vertex->shadow_vertex;
+ if (shadow_vertex != NULL &&
+ (shadow_vertex == va || shadow_vertex == vb || shadow_vertex == vc))
+ continue;
+ x = vertex->x;
+ y = vertex->y;
+ if (left(ba.A, ba.B, ba.C, x, y) &&
+ left(ac.A, ac.B, ac.C, x, y) && left(cb.A, cb.B, cb.C, x, y))
+ return GL_FALSE;
+ }
+ return GL_TRUE;
+}
+
+static GLboolean
+diagonal_cw(tess_vertex * va,
+ tess_vertex * vb,
+ GLUtriangulatorObj * tobj, tess_contour * contour)
+{
+ tess_vertex *vc = va->next, *vertex, *shadow_vertex;
+ struct
+ {
+ GLdouble A, B, C;
+ }
+ ac, cb, ba;
+ GLdouble x, y;
+
+ GLint res = convex_cw(va, vc, vb, tobj);
+ if (res == 0)
+ return GL_FALSE;
+ if (res == -1)
+ return GL_TRUE;
+
+ ba.A = vb->y - va->y;
+ ba.B = va->x - vb->x;
+ ba.C = -ba.A * va->x - ba.B * va->y;
+ ac.A = va->y - vc->y;
+ ac.B = vc->x - va->x;
+ ac.C = -ac.A * vc->x - ac.B * vc->y;
+ cb.A = vc->y - vb->y;
+ cb.B = vb->x - vc->x;
+ cb.C = -cb.A * vb->x - cb.B * vb->y;
+ for (vertex = vb->next; vertex != va; vertex = vertex->next) {
+ shadow_vertex = vertex->shadow_vertex;
+ if (shadow_vertex != NULL &&
+ (shadow_vertex == va || shadow_vertex == vb || shadow_vertex == vc))
+ continue;
+ x = vertex->x;
+ y = vertex->y;
+ if (right(ba.A, ba.B, ba.C, x, y) &&
+ right(ac.A, ac.B, ac.C, x, y) && right(cb.A, cb.B, cb.C, x, y))
+ return GL_FALSE;
+ }
+ return GL_TRUE;
+}
+
+static void
+clip_ear(GLUtriangulatorObj * tobj, tess_vertex * v, tess_contour * contour)
+{
+ emit_triangle(tobj, v->previous, v, v->next);
+ /* the first in the list */
+ if (contour->vertices == v) {
+ contour->vertices = v->next;
+ contour->last_vertex->next = v->next;
+ v->next->previous = contour->last_vertex;
+ }
+ else
+ /* the last ? */
+ if (contour->last_vertex == v) {
+ contour->vertices->previous = v->previous;
+ v->previous->next = v->next;
+ contour->last_vertex = v->previous;
+ }
+ else {
+ v->next->previous = v->previous;
+ v->previous->next = v->next;
+ }
+ free(v);
+ --(contour->vertex_cnt);
+}
+
+static void
+clip_ear_with_edge_flag(GLUtriangulatorObj * tobj,
+ tess_vertex * v, tess_contour * contour)
+{
+ emit_triangle_with_edge_flag(tobj, v->previous, v->previous->edge_flag,
+ v, v->edge_flag, v->next, GL_FALSE);
+ v->previous->edge_flag = GL_FALSE;
+ /* the first in the list */
+ if (contour->vertices == v) {
+ contour->vertices = v->next;
+ contour->last_vertex->next = v->next;
+ v->next->previous = contour->last_vertex;
+ }
+ else
+ /* the last ? */
+ if (contour->last_vertex == v) {
+ contour->vertices->previous = v->previous;
+ v->previous->next = v->next;
+ contour->last_vertex = v->previous;
+ }
+ else {
+ v->next->previous = v->previous;
+ v->previous->next = v->next;
+ }
+ free(v);
+ --(contour->vertex_cnt);
+}
+
+static void
+triangulate_ccw(GLUtriangulatorObj * tobj, tess_contour * contour)
+{
+ tess_vertex *vertex;
+ GLuint vertex_cnt = contour->vertex_cnt;
+
+ while (vertex_cnt > 3) {
+ vertex = contour->vertices;
+ while (diagonal_ccw(vertex, vertex->next->next, tobj, contour) ==
+ GL_FALSE && tobj->error == GLU_NO_ERROR)
+ vertex = vertex->next;
+ if (tobj->error != GLU_NO_ERROR)
+ return;
+ clip_ear(tobj, vertex->next, contour);
+ --vertex_cnt;
+ }
+}
+
+static void
+triangulate_cw(GLUtriangulatorObj * tobj, tess_contour * contour)
+{
+ tess_vertex *vertex;
+ GLuint vertex_cnt = contour->vertex_cnt;
+
+ while (vertex_cnt > 3) {
+ vertex = contour->vertices;
+ while (diagonal_cw(vertex, vertex->next->next, tobj, contour) ==
+ GL_FALSE && tobj->error == GLU_NO_ERROR)
+ vertex = vertex->next;
+ if (tobj->error != GLU_NO_ERROR)
+ return;
+ clip_ear(tobj, vertex->next, contour);
+ --vertex_cnt;
+ }
+}
+
+static void
+triangulate_ccw_with_edge_flag(GLUtriangulatorObj * tobj,
+ tess_contour * contour)
+{
+ tess_vertex *vertex;
+ GLuint vertex_cnt = contour->vertex_cnt;
+
+ while (vertex_cnt > 3) {
+ vertex = contour->vertices;
+ while (diagonal_ccw(vertex, vertex->next->next, tobj, contour) ==
+ GL_FALSE && tobj->error == GLU_NO_ERROR)
+ vertex = vertex->next;
+ if (tobj->error != GLU_NO_ERROR)
+ return;
+ clip_ear_with_edge_flag(tobj, vertex->next, contour);
+ --vertex_cnt;
+ }
+}
+
+static void
+triangulate_cw_with_edge_flag(GLUtriangulatorObj * tobj,
+ tess_contour * contour)
+{
+ tess_vertex *vertex;
+ GLuint vertex_cnt = contour->vertex_cnt;
+
+ while (vertex_cnt > 3) {
+ vertex = contour->vertices;
+ while (diagonal_cw(vertex, vertex->next->next, tobj, contour) ==
+ GL_FALSE && tobj->error == GLU_NO_ERROR)
+ vertex = vertex->next;
+ if (tobj->error != GLU_NO_ERROR)
+ return;
+ clip_ear_with_edge_flag(tobj, vertex->next, contour);
+ --vertex_cnt;
+ }
+}
+
+void
+tess_tesselate(GLUtriangulatorObj * tobj)
+{
+ tess_contour *contour;
+
+ for (contour = tobj->contours; contour != NULL; contour = contour->next) {
+ if (contour->orientation == GLU_CCW) {
+ triangulate_ccw(tobj, contour);
+ }
+ else {
+ triangulate_cw(tobj, contour);
+ }
+ if (tobj->error != GLU_NO_ERROR)
+ return;
+
+ /* emit the last triangle */
+ emit_triangle(tobj, contour->vertices, contour->vertices->next,
+ contour->vertices->next->next);
+ }
+}
+
+void
+tess_tesselate_with_edge_flag(GLUtriangulatorObj * tobj)
+{
+ tess_contour *contour;
+
+ edge_flag = GL_TRUE;
+ /* first callback with edgeFlag set to GL_TRUE */
+ (tobj->callbacks.edgeFlag) (GL_TRUE);
+
+ for (contour = tobj->contours; contour != NULL; contour = contour->next) {
+ if (contour->orientation == GLU_CCW)
+ triangulate_ccw_with_edge_flag(tobj, contour);
+ else
+ triangulate_cw_with_edge_flag(tobj, contour);
+ if (tobj->error != GLU_NO_ERROR)
+ return;
+ /* emit the last triangle */
+ emit_triangle_with_edge_flag(tobj, contour->vertices,
+ contour->vertices->edge_flag,
+ contour->vertices->next,
+ contour->vertices->next->edge_flag,
+ contour->vertices->next->next,
+ contour->vertices->next->next->edge_flag);
+ }
+}
+
+static void
+emit_triangle(GLUtriangulatorObj * tobj,
+ tess_vertex * v1, tess_vertex * v2, tess_vertex * v3)
+{
+ (tobj->callbacks.begin) (GL_TRIANGLES);
+ (tobj->callbacks.vertex) (v1->data);
+ (tobj->callbacks.vertex) (v2->data);
+ (tobj->callbacks.vertex) (v3->data);
+ (tobj->callbacks.end) ();
+}
+
+static void
+emit_triangle_with_edge_flag(GLUtriangulatorObj * tobj,
+ tess_vertex * v1,
+ GLboolean edge_flag1,
+ tess_vertex * v2,
+ GLboolean edge_flag2,
+ tess_vertex * v3, GLboolean edge_flag3)
+{
+ (tobj->callbacks.begin) (GL_TRIANGLES);
+ if (edge_flag1 != edge_flag) {
+ edge_flag = (edge_flag == GL_TRUE ? GL_FALSE : GL_TRUE);
+ (tobj->callbacks.edgeFlag) (edge_flag);
+ }
+ (tobj->callbacks.vertex) (v1->data);
+ if (edge_flag2 != edge_flag) {
+ edge_flag = (edge_flag == GL_TRUE ? GL_FALSE : GL_TRUE);
+ (tobj->callbacks.edgeFlag) (edge_flag);
+ }
+ (tobj->callbacks.vertex) (v2->data);
+ if (edge_flag3 != edge_flag) {
+ edge_flag = (edge_flag == GL_TRUE ? GL_FALSE : GL_TRUE);
+ (tobj->callbacks.edgeFlag) (edge_flag);
+ }
+ (tobj->callbacks.vertex) (v3->data);
+ (tobj->callbacks.end) ();
+}
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