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Diffstat (limited to 'libtess/render.c')
| -rw-r--r-- | libtess/render.c | 505 |
1 files changed, 0 insertions, 505 deletions
diff --git a/libtess/render.c b/libtess/render.c deleted file mode 100644 index 89b442e..0000000 --- a/libtess/render.c +++ /dev/null @@ -1,505 +0,0 @@ -/* -** License Applicability. Except to the extent portions of this file are -** made subject to an alternative license as permitted in the SGI Free -** Software License B, Version 1.1 (the "License"), the contents of this -** file are subject only to the provisions of the License. You may not use -** this file except in compliance with the License. You may obtain a copy -** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600 -** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at: -** -** http://oss.sgi.com/projects/FreeB -** -** Note that, as provided in the License, the Software is distributed on an -** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS -** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND -** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A -** PARTICULAR PURPOSE, AND NON-INFRINGEMENT. -** -** Original Code. The Original Code is: OpenGL Sample Implementation, -** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics, -** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc. -** Copyright in any portions created by third parties is as indicated -** elsewhere herein. All Rights Reserved. -** -** Additional Notice Provisions: The application programming interfaces -** established by SGI in conjunction with the Original Code are The -** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released -** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version -** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X -** Window System(R) (Version 1.3), released October 19, 1998. This software -** was created using the OpenGL(R) version 1.2.1 Sample Implementation -** published by SGI, but has not been independently verified as being -** compliant with the OpenGL(R) version 1.2.1 Specification. -** -*/ -/* -** Author: Eric Veach, July 1994. -** -** $Date$ $Revision$ -** $Header$ -*/ - -#include "gluos.h" -#include <assert.h> -#include <stddef.h> -#include "mesh.h" -#include "tess.h" -#include "render.h" - -#define TRUE 1 -#define FALSE 0 - -/* This structure remembers the information we need about a primitive - * to be able to render it later, once we have determined which - * primitive is able to use the most triangles. - */ -struct FaceCount { - long size; /* number of triangles used */ - GLUhalfEdge *eStart; /* edge where this primitive starts */ - void (*render)(GLUtesselator *, GLUhalfEdge *, long); - /* routine to render this primitive */ -}; - -static struct FaceCount MaximumFan( GLUhalfEdge *eOrig ); -static struct FaceCount MaximumStrip( GLUhalfEdge *eOrig ); - -static void RenderFan( GLUtesselator *tess, GLUhalfEdge *eStart, long size ); -static void RenderStrip( GLUtesselator *tess, GLUhalfEdge *eStart, long size ); -static void RenderTriangle( GLUtesselator *tess, GLUhalfEdge *eStart, - long size ); - -static void RenderMaximumFaceGroup( GLUtesselator *tess, GLUface *fOrig ); -static void RenderLonelyTriangles( GLUtesselator *tess, GLUface *head ); - - - -/************************ Strips and Fans decomposition ******************/ - -/* __gl_renderMesh( tess, mesh ) takes a mesh and breaks it into triangle - * fans, strips, and separate triangles. A substantial effort is made - * to use as few rendering primitives as possible (ie. to make the fans - * and strips as large as possible). - * - * The rendering output is provided as callbacks (see the api). - */ -void __gl_renderMesh( GLUtesselator *tess, GLUmesh *mesh ) -{ - GLUface *f; - - /* Make a list of separate triangles so we can render them all at once */ - tess->lonelyTriList = NULL; - - for( f = mesh->fHead.next; f != &mesh->fHead; f = f->next ) { - f->marked = FALSE; - } - for( f = mesh->fHead.next; f != &mesh->fHead; f = f->next ) { - - /* We examine all faces in an arbitrary order. Whenever we find - * an unprocessed face F, we output a group of faces including F - * whose size is maximum. - */ - if( f->inside && ! f->marked ) { - RenderMaximumFaceGroup( tess, f ); - assert( f->marked ); - } - } - if( tess->lonelyTriList != NULL ) { - RenderLonelyTriangles( tess, tess->lonelyTriList ); - tess->lonelyTriList = NULL; - } -} - - -static void RenderMaximumFaceGroup( GLUtesselator *tess, GLUface *fOrig ) -{ - /* We want to find the largest triangle fan or strip of unmarked faces - * which includes the given face fOrig. There are 3 possible fans - * passing through fOrig (one centered at each vertex), and 3 possible - * strips (one for each CCW permutation of the vertices). Our strategy - * is to try all of these, and take the primitive which uses the most - * triangles (a greedy approach). - */ - GLUhalfEdge *e = fOrig->anEdge; - struct FaceCount max, newFace; - - max.size = 1; - max.eStart = e; - max.render = &RenderTriangle; - - if( ! tess->flagBoundary ) { - newFace = MaximumFan( e ); if( newFace.size > max.size ) { max = newFace; } - newFace = MaximumFan( e->Lnext ); if( newFace.size > max.size ) { max = newFace; } - newFace = MaximumFan( e->Lprev ); if( newFace.size > max.size ) { max = newFace; } - - newFace = MaximumStrip( e ); if( newFace.size > max.size ) { max = newFace; } - newFace = MaximumStrip( e->Lnext ); if( newFace.size > max.size ) { max = newFace; } - newFace = MaximumStrip( e->Lprev ); if( newFace.size > max.size ) { max = newFace; } - } - (*(max.render))( tess, max.eStart, max.size ); -} - - -/* Macros which keep track of faces we have marked temporarily, and allow - * us to backtrack when necessary. With triangle fans, this is not - * really necessary, since the only awkward case is a loop of triangles - * around a single origin vertex. However with strips the situation is - * more complicated, and we need a general tracking method like the - * one here. - */ -#define Marked(f) (! (f)->inside || (f)->marked) - -#define AddToTrail(f,t) ((f)->trail = (t), (t) = (f), (f)->marked = TRUE) - -#define FreeTrail(t) if( 1 ) { \ - while( (t) != NULL ) { \ - (t)->marked = FALSE; t = (t)->trail; \ - } \ - } else /* absorb trailing semicolon */ - - - -static struct FaceCount MaximumFan( GLUhalfEdge *eOrig ) -{ - /* eOrig->Lface is the face we want to render. We want to find the size - * of a maximal fan around eOrig->Org. To do this we just walk around - * the origin vertex as far as possible in both directions. - */ - struct FaceCount newFace = { 0, NULL, &RenderFan }; - GLUface *trail = NULL; - GLUhalfEdge *e; - - for( e = eOrig; ! Marked( e->Lface ); e = e->Onext ) { - AddToTrail( e->Lface, trail ); - ++newFace.size; - } - for( e = eOrig; ! Marked( e->Rface ); e = e->Oprev ) { - AddToTrail( e->Rface, trail ); - ++newFace.size; - } - newFace.eStart = e; - /*LINTED*/ - FreeTrail( trail ); - return newFace; -} - - -#define IsEven(n) (((n) & 1) == 0) - -static struct FaceCount MaximumStrip( GLUhalfEdge *eOrig ) -{ - /* Here we are looking for a maximal strip that contains the vertices - * eOrig->Org, eOrig->Dst, eOrig->Lnext->Dst (in that order or the - * reverse, such that all triangles are oriented CCW). - * - * Again we walk forward and backward as far as possible. However for - * strips there is a twist: to get CCW orientations, there must be - * an *even* number of triangles in the strip on one side of eOrig. - * We walk the strip starting on a side with an even number of triangles; - * if both side have an odd number, we are forced to shorten one side. - */ - struct FaceCount newFace = { 0, NULL, &RenderStrip }; - long headSize = 0, tailSize = 0; - GLUface *trail = NULL; - GLUhalfEdge *e, *eTail, *eHead; - - for( e = eOrig; ! Marked( e->Lface ); ++tailSize, e = e->Onext ) { - AddToTrail( e->Lface, trail ); - ++tailSize; - e = e->Dprev; - if( Marked( e->Lface )) break; - AddToTrail( e->Lface, trail ); - } - eTail = e; - - for( e = eOrig; ! Marked( e->Rface ); ++headSize, e = e->Dnext ) { - AddToTrail( e->Rface, trail ); - ++headSize; - e = e->Oprev; - if( Marked( e->Rface )) break; - AddToTrail( e->Rface, trail ); - } - eHead = e; - - newFace.size = tailSize + headSize; - if( IsEven( tailSize )) { - newFace.eStart = eTail->Sym; - } else if( IsEven( headSize )) { - newFace.eStart = eHead; - } else { - /* Both sides have odd length, we must shorten one of them. In fact, - * we must start from eHead to guarantee inclusion of eOrig->Lface. - */ - --newFace.size; - newFace.eStart = eHead->Onext; - } - /*LINTED*/ - FreeTrail( trail ); - return newFace; -} - - -static void RenderTriangle( GLUtesselator *tess, GLUhalfEdge *e, long size ) -{ - /* Just add the triangle to a triangle list, so we can render all - * the separate triangles at once. - */ - assert( size == 1 ); - AddToTrail( e->Lface, tess->lonelyTriList ); -} - - -static void RenderLonelyTriangles( GLUtesselator *tess, GLUface *f ) -{ - /* Now we render all the separate triangles which could not be - * grouped into a triangle fan or strip. - */ - GLUhalfEdge *e; - int newState; - int edgeState = -1; /* force edge state output for first vertex */ - - CALL_BEGIN_OR_BEGIN_DATA( GL_TRIANGLES ); - - for( ; f != NULL; f = f->trail ) { - /* Loop once for each edge (there will always be 3 edges) */ - - e = f->anEdge; - do { - if( tess->flagBoundary ) { - /* Set the "edge state" to TRUE just before we output the - * first vertex of each edge on the polygon boundary. - */ - newState = ! e->Rface->inside; - if( edgeState != newState ) { - edgeState = newState; - CALL_EDGE_FLAG_OR_EDGE_FLAG_DATA( edgeState ); - } - } - CALL_VERTEX_OR_VERTEX_DATA( e->Org->data ); - - e = e->Lnext; - } while( e != f->anEdge ); - } - CALL_END_OR_END_DATA(); -} - - -static void RenderFan( GLUtesselator *tess, GLUhalfEdge *e, long size ) -{ - /* Render as many CCW triangles as possible in a fan starting from - * edge "e". The fan *should* contain exactly "size" triangles - * (otherwise we've goofed up somewhere). - */ - CALL_BEGIN_OR_BEGIN_DATA( GL_TRIANGLE_FAN ); - CALL_VERTEX_OR_VERTEX_DATA( e->Org->data ); - CALL_VERTEX_OR_VERTEX_DATA( e->Dst->data ); - - while( ! Marked( e->Lface )) { - e->Lface->marked = TRUE; - --size; - e = e->Onext; - CALL_VERTEX_OR_VERTEX_DATA( e->Dst->data ); - } - - assert( size == 0 ); - CALL_END_OR_END_DATA(); -} - - -static void RenderStrip( GLUtesselator *tess, GLUhalfEdge *e, long size ) -{ - /* Render as many CCW triangles as possible in a strip starting from - * edge "e". The strip *should* contain exactly "size" triangles - * (otherwise we've goofed up somewhere). - */ - CALL_BEGIN_OR_BEGIN_DATA( GL_TRIANGLE_STRIP ); - CALL_VERTEX_OR_VERTEX_DATA( e->Org->data ); - CALL_VERTEX_OR_VERTEX_DATA( e->Dst->data ); - - while( ! Marked( e->Lface )) { - e->Lface->marked = TRUE; - --size; - e = e->Dprev; - CALL_VERTEX_OR_VERTEX_DATA( e->Org->data ); - if( Marked( e->Lface )) break; - - e->Lface->marked = TRUE; - --size; - e = e->Onext; - CALL_VERTEX_OR_VERTEX_DATA( e->Dst->data ); - } - - assert( size == 0 ); - CALL_END_OR_END_DATA(); -} - - -/************************ Boundary contour decomposition ******************/ - -/* __gl_renderBoundary( tess, mesh ) takes a mesh, and outputs one - * contour for each face marked "inside". The rendering output is - * provided as callbacks (see the api). - */ -void __gl_renderBoundary( GLUtesselator *tess, GLUmesh *mesh ) -{ - GLUface *f; - GLUhalfEdge *e; - - for( f = mesh->fHead.next; f != &mesh->fHead; f = f->next ) { - if( f->inside ) { - CALL_BEGIN_OR_BEGIN_DATA( GL_LINE_LOOP ); - e = f->anEdge; - do { - CALL_VERTEX_OR_VERTEX_DATA( e->Org->data ); - e = e->Lnext; - } while( e != f->anEdge ); - CALL_END_OR_END_DATA(); - } - } -} - - -/************************ Quick-and-dirty decomposition ******************/ - -#define SIGN_INCONSISTENT 2 - -static int ComputeNormal( GLUtesselator *tess, GLdouble norm[3], int check ) -/* - * If check==FALSE, we compute the polygon normal and place it in norm[]. - * If check==TRUE, we check that each triangle in the fan from v0 has a - * consistent orientation with respect to norm[]. If triangles are - * consistently oriented CCW, return 1; if CW, return -1; if all triangles - * are degenerate return 0; otherwise (no consistent orientation) return - * SIGN_INCONSISTENT. - */ -{ - CachedVertex *v0 = tess->cache; - CachedVertex *vn = v0 + tess->cacheCount; - CachedVertex *vc; - GLdouble dot, xc, yc, zc, xp, yp, zp, n[3]; - int sign = 0; - - /* Find the polygon normal. It is important to get a reasonable - * normal even when the polygon is self-intersecting (eg. a bowtie). - * Otherwise, the computed normal could be very tiny, but perpendicular - * to the true plane of the polygon due to numerical noise. Then all - * the triangles would appear to be degenerate and we would incorrectly - * decompose the polygon as a fan (or simply not render it at all). - * - * We use a sum-of-triangles normal algorithm rather than the more - * efficient sum-of-trapezoids method (used in CheckOrientation() - * in normal.c). This lets us explicitly reverse the signed area - * of some triangles to get a reasonable normal in the self-intersecting - * case. - */ - if( ! check ) { - norm[0] = norm[1] = norm[2] = 0.0; - } - - vc = v0 + 1; - xc = vc->coords[0] - v0->coords[0]; - yc = vc->coords[1] - v0->coords[1]; - zc = vc->coords[2] - v0->coords[2]; - while( ++vc < vn ) { - xp = xc; yp = yc; zp = zc; - xc = vc->coords[0] - v0->coords[0]; - yc = vc->coords[1] - v0->coords[1]; - zc = vc->coords[2] - v0->coords[2]; - - /* Compute (vp - v0) cross (vc - v0) */ - n[0] = yp*zc - zp*yc; - n[1] = zp*xc - xp*zc; - n[2] = xp*yc - yp*xc; - - dot = n[0]*norm[0] + n[1]*norm[1] + n[2]*norm[2]; - if( ! check ) { - /* Reverse the contribution of back-facing triangles to get - * a reasonable normal for self-intersecting polygons (see above) - */ - if( dot >= 0 ) { - norm[0] += n[0]; norm[1] += n[1]; norm[2] += n[2]; - } else { - norm[0] -= n[0]; norm[1] -= n[1]; norm[2] -= n[2]; - } - } else if( dot != 0 ) { - /* Check the new orientation for consistency with previous triangles */ - if( dot > 0 ) { - if( sign < 0 ) return SIGN_INCONSISTENT; - sign = 1; - } else { - if( sign > 0 ) return SIGN_INCONSISTENT; - sign = -1; - } - } - } - return sign; -} - -/* __gl_renderCache( tess ) takes a single contour and tries to render it - * as a triangle fan. This handles convex polygons, as well as some - * non-convex polygons if we get lucky. - * - * Returns TRUE if the polygon was successfully rendered. The rendering - * output is provided as callbacks (see the api). - */ -GLboolean __gl_renderCache( GLUtesselator *tess ) -{ - CachedVertex *v0 = tess->cache; - CachedVertex *vn = v0 + tess->cacheCount; - CachedVertex *vc; - GLdouble norm[3]; - int sign; - - if( tess->cacheCount < 3 ) { - /* Degenerate contour -- no output */ - return TRUE; - } - - 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, FALSE ); - } - - sign = ComputeNormal( tess, norm, TRUE ); - if( sign == SIGN_INCONSISTENT ) { - /* Fan triangles did not have a consistent orientation */ - return FALSE; - } - if( sign == 0 ) { - /* All triangles were degenerate */ - return TRUE; - } - - /* Make sure we do the right thing for each winding rule */ - switch( tess->windingRule ) { - case GLU_TESS_WINDING_ODD: - case GLU_TESS_WINDING_NONZERO: - break; - case GLU_TESS_WINDING_POSITIVE: - if( sign < 0 ) return TRUE; - break; - case GLU_TESS_WINDING_NEGATIVE: - if( sign > 0 ) return TRUE; - break; - case GLU_TESS_WINDING_ABS_GEQ_TWO: - return TRUE; - } - - CALL_BEGIN_OR_BEGIN_DATA((unsigned int) (tess->boundaryOnly ? GL_LINE_LOOP - : (tess->cacheCount > 3) ? GL_TRIANGLE_FAN - : GL_TRIANGLES) ); - - CALL_VERTEX_OR_VERTEX_DATA( v0->data ); - if( sign > 0 ) { - for( vc = v0+1; vc < vn; ++vc ) { - CALL_VERTEX_OR_VERTEX_DATA( vc->data ); - } - } else { - for( vc = vn-1; vc > v0; --vc ) { - CALL_VERTEX_OR_VERTEX_DATA( vc->data ); - } - } - CALL_END_OR_END_DATA(); - return TRUE; -} |