mutter/cogl/tesselator/normal.c
Neil Roberts a0a06f0342 cogl/tesselator: Update to the latest code from GLU
This grabs the latest code for libtess from git Mesa. This is mostly
so that we can get the following commit which fixes a lot of compiler
warnings in Clutter:

commit 75acb896c6da758d03e86f8725d6ca0cb2c6ad82
Author: Neil Roberts <neil@linux.intel.com>
Date:   Wed Jun 30 12:41:11 2010 +0100

    glu: Fix some compiler warnings in libtess
    
    When compiled with the more aggressive compiler warnings such as
    -Wshadow and -Wempty-body the libtess code gives a lot more
    warnings. This fixes the following issues:
    
    * The 'Swap' macro tries to combine multiple statements into one and
      then consume the trailing semicolon by using if(1){/*...*/}else.
      This gives warnings because the else part ends up with an empty
      statement. It also seems a bit dangerous because if the semicolon
      were missed then it would still be valid syntax but it would just
      ignore the following statement. This patch replaces it with the more
      common idiom do { /*...*/ } while(0).
    
    * 'free' was being used as a local variable name but this shadows the
      global function. This has been renamed to 'free_handle'
    
    * TRUE and FALSE were being unconditionally defined. Although this
      isn't currently a problem it seems better to guard them with #ifndef
      because it's quite common for them to be defined in other headers.
    
    https://bugs.freedesktop.org/show_bug.cgi?id=28845
2010-06-30 16:35:33 +01:00

258 lines
7.6 KiB
C

/*
* SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
* Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice including the dates of first publication and
* either this permission notice or a reference to
* http://oss.sgi.com/projects/FreeB/
* shall be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
* OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
* Except as contained in this notice, the name of Silicon Graphics, Inc.
* shall not be used in advertising or otherwise to promote the sale, use or
* other dealings in this Software without prior written authorization from
* Silicon Graphics, Inc.
*/
/*
** Author: Eric Veach, July 1994.
**
*/
#include "gluos.h"
#include "mesh.h"
#include "tess.h"
#include "normal.h"
#include <math.h>
#include <assert.h>
#ifndef TRUE
#define TRUE 1
#endif
#ifndef FALSE
#define FALSE 0
#endif
#define Dot(u,v) (u[0]*v[0] + u[1]*v[1] + u[2]*v[2])
#if 0
static void Normalize( GLdouble v[3] )
{
GLdouble len = v[0]*v[0] + v[1]*v[1] + v[2]*v[2];
assert( len > 0 );
len = sqrt( len );
v[0] /= len;
v[1] /= len;
v[2] /= len;
}
#endif
#undef ABS
#define ABS(x) ((x) < 0 ? -(x) : (x))
static int LongAxis( GLdouble v[3] )
{
int i = 0;
if( ABS(v[1]) > ABS(v[0]) ) { i = 1; }
if( ABS(v[2]) > ABS(v[i]) ) { i = 2; }
return i;
}
static void ComputeNormal( GLUtesselator *tess, GLdouble norm[3] )
{
GLUvertex *v, *v1, *v2;
GLdouble c, tLen2, maxLen2;
GLdouble maxVal[3], minVal[3], d1[3], d2[3], tNorm[3];
GLUvertex *maxVert[3], *minVert[3];
GLUvertex *vHead = &tess->mesh->vHead;
int i;
maxVal[0] = maxVal[1] = maxVal[2] = -2 * GLU_TESS_MAX_COORD;
minVal[0] = minVal[1] = minVal[2] = 2 * GLU_TESS_MAX_COORD;
for( v = vHead->next; v != vHead; v = v->next ) {
for( i = 0; i < 3; ++i ) {
c = v->coords[i];
if( c < minVal[i] ) { minVal[i] = c; minVert[i] = v; }
if( c > maxVal[i] ) { maxVal[i] = c; maxVert[i] = v; }
}
}
/* Find two vertices separated by at least 1/sqrt(3) of the maximum
* distance between any two vertices
*/
i = 0;
if( maxVal[1] - minVal[1] > maxVal[0] - minVal[0] ) { i = 1; }
if( maxVal[2] - minVal[2] > maxVal[i] - minVal[i] ) { i = 2; }
if( minVal[i] >= maxVal[i] ) {
/* All vertices are the same -- normal doesn't matter */
norm[0] = 0; norm[1] = 0; norm[2] = 1;
return;
}
/* Look for a third vertex which forms the triangle with maximum area
* (Length of normal == twice the triangle area)
*/
maxLen2 = 0;
v1 = minVert[i];
v2 = maxVert[i];
d1[0] = v1->coords[0] - v2->coords[0];
d1[1] = v1->coords[1] - v2->coords[1];
d1[2] = v1->coords[2] - v2->coords[2];
for( v = vHead->next; v != vHead; v = v->next ) {
d2[0] = v->coords[0] - v2->coords[0];
d2[1] = v->coords[1] - v2->coords[1];
d2[2] = v->coords[2] - v2->coords[2];
tNorm[0] = d1[1]*d2[2] - d1[2]*d2[1];
tNorm[1] = d1[2]*d2[0] - d1[0]*d2[2];
tNorm[2] = d1[0]*d2[1] - d1[1]*d2[0];
tLen2 = tNorm[0]*tNorm[0] + tNorm[1]*tNorm[1] + tNorm[2]*tNorm[2];
if( tLen2 > maxLen2 ) {
maxLen2 = tLen2;
norm[0] = tNorm[0];
norm[1] = tNorm[1];
norm[2] = tNorm[2];
}
}
if( maxLen2 <= 0 ) {
/* All points lie on a single line -- any decent normal will do */
norm[0] = norm[1] = norm[2] = 0;
norm[LongAxis(d1)] = 1;
}
}
static void CheckOrientation( GLUtesselator *tess )
{
GLdouble area;
GLUface *f, *fHead = &tess->mesh->fHead;
GLUvertex *v, *vHead = &tess->mesh->vHead;
GLUhalfEdge *e;
/* When we compute the normal automatically, we choose the orientation
* so that the sum of the signed areas of all contours is non-negative.
*/
area = 0;
for( f = fHead->next; f != fHead; f = f->next ) {
e = f->anEdge;
if( e->winding <= 0 ) continue;
do {
area += (e->Org->s - e->Dst->s) * (e->Org->t + e->Dst->t);
e = e->Lnext;
} while( e != f->anEdge );
}
if( area < 0 ) {
/* Reverse the orientation by flipping all the t-coordinates */
for( v = vHead->next; v != vHead; v = v->next ) {
v->t = - v->t;
}
tess->tUnit[0] = - tess->tUnit[0];
tess->tUnit[1] = - tess->tUnit[1];
tess->tUnit[2] = - tess->tUnit[2];
}
}
#ifdef FOR_TRITE_TEST_PROGRAM
#include <stdlib.h>
extern int RandomSweep;
#define S_UNIT_X (RandomSweep ? (2*drand48()-1) : 1.0)
#define S_UNIT_Y (RandomSweep ? (2*drand48()-1) : 0.0)
#else
#if defined(SLANTED_SWEEP)
/* The "feature merging" is not intended to be complete. There are
* special cases where edges are nearly parallel to the sweep line
* which are not implemented. The algorithm should still behave
* robustly (ie. produce a reasonable tesselation) in the presence
* of such edges, however it may miss features which could have been
* merged. We could minimize this effect by choosing the sweep line
* direction to be something unusual (ie. not parallel to one of the
* coordinate axes).
*/
#define S_UNIT_X 0.50941539564955385 /* Pre-normalized */
#define S_UNIT_Y 0.86052074622010633
#else
#define S_UNIT_X 1.0
#define S_UNIT_Y 0.0
#endif
#endif
/* Determine the polygon normal and project vertices onto the plane
* of the polygon.
*/
void __gl_projectPolygon( GLUtesselator *tess )
{
GLUvertex *v, *vHead = &tess->mesh->vHead;
GLdouble norm[3];
GLdouble *sUnit, *tUnit;
int i, computedNormal = FALSE;
norm[0] = tess->normal[0];
norm[1] = tess->normal[1];
norm[2] = tess->normal[2];
if( norm[0] == 0 && norm[1] == 0 && norm[2] == 0 ) {
ComputeNormal( tess, norm );
computedNormal = TRUE;
}
sUnit = tess->sUnit;
tUnit = tess->tUnit;
i = LongAxis( norm );
#if defined(FOR_TRITE_TEST_PROGRAM) || defined(TRUE_PROJECT)
/* Choose the initial sUnit vector to be approximately perpendicular
* to the normal.
*/
Normalize( norm );
sUnit[i] = 0;
sUnit[(i+1)%3] = S_UNIT_X;
sUnit[(i+2)%3] = S_UNIT_Y;
/* Now make it exactly perpendicular */
w = Dot( sUnit, norm );
sUnit[0] -= w * norm[0];
sUnit[1] -= w * norm[1];
sUnit[2] -= w * norm[2];
Normalize( sUnit );
/* Choose tUnit so that (sUnit,tUnit,norm) form a right-handed frame */
tUnit[0] = norm[1]*sUnit[2] - norm[2]*sUnit[1];
tUnit[1] = norm[2]*sUnit[0] - norm[0]*sUnit[2];
tUnit[2] = norm[0]*sUnit[1] - norm[1]*sUnit[0];
Normalize( tUnit );
#else
/* Project perpendicular to a coordinate axis -- better numerically */
sUnit[i] = 0;
sUnit[(i+1)%3] = S_UNIT_X;
sUnit[(i+2)%3] = S_UNIT_Y;
tUnit[i] = 0;
tUnit[(i+1)%3] = (norm[i] > 0) ? -S_UNIT_Y : S_UNIT_Y;
tUnit[(i+2)%3] = (norm[i] > 0) ? S_UNIT_X : -S_UNIT_X;
#endif
/* Project the vertices onto the sweep plane */
for( v = vHead->next; v != vHead; v = v->next ) {
v->s = Dot( v->coords, sUnit );
v->t = Dot( v->coords, tUnit );
}
if( computedNormal ) {
CheckOrientation( tess );
}
}