src/common/mesh.h

/* RCSid $Id$ */
/*
 * Header for compact triangle mesh geometry
 *
 *  Include after standard.h, object.h and octree.h
 */

#include "copyright.h"

#ifndef uint4
#define uint4   unsigned int4
#endif
#ifndef BYTE
#define BYTE    unsigned char
#endif

/*
 * Vertex space is minimized without compromising accuracy by using a
 * 4-byte unsigned int to indicate position in the enclosing octree cube.
 * The same trick is used for any local (u,v) coordinates, whose limits
 * are recorded separately in the parent MESH structure.  The uvlimit's
 * in the MESH structure are set such that (0,0) is out of range, so
 * we use this to indicate an unspecified local coordinate.
 * A vertex normal, if specified, is stored in a single 4-byte
 * integer using the codec in dircode.c.  The encodedir() function
 * never generates 0, so we can use this for unspecified normals.
 *
 * Vertex ID's are encoded using the bottom 8 bits of a 4-byte integer
 * to index a vertex in a patch indicated by the 20 bits above (9-29).
 * For triangle ID's, the top 10 bits (11-31) indicate the patch, and
 * the 10th bit indicates whether the triangle joins patches.
 * If not, then the bottom 9 bits index into the local PTri array.
 * If it's a joiner, then the 9th bit indicates whether the triangle joins
 * two patches, in which case the bottom 8 bits index the PJoin2 array.
 * Otherwise, the bottom 8 bits index the PJoin1 array.
 *
 * These shenanigans minimize vertex reference memory requirements
 * in compiled mesh structures, where the octree leaves contain sets 
 * of triangle ID's rather than the more usual objects.  It seems like
 * a lot of effort, but it can reduce mesh storage by a factor of 3
 * or more.  This is important, as the whole point is to model very
 * complicated geometry with this structure, and memory is the main
 * limitation.  (We also optimize intersection tests for triangles.)
 */

/* A triangle mesh patch */
typedef struct {
        uint4           (*xyz)[3];      /* up to 256 patch vertices */
        int4            *norm;          /* vertex normals */
        uint4           (*uv)[2];       /* vertex local coordinates */
        struct PTri {
                BYTE            v1, v2, v3;     /* local vertices */
        }               *tri;           /* local triangles */
        struct PJoin1 {
                int4            v1j;            /* non-local vertex */
                BYTE            v2, v3;         /* local vertices */
        }               *j1tri;         /* joiner triangles */
        struct PJoin2 {
                int4            v1j, v2j;       /* non-local vertices */
                BYTE            v3;             /* local vertex */
        }               *j2tri;         /* double joiner triangles */
        short           nverts;         /* vertex count */
        short           ntris;          /* triangle count */
        short           nj1tris;        /* joiner triangle count */
        short           nj2tris;        /* double joiner triangle count */
} MESHPATCH;

/* A loaded mesh */
typedef struct mesh {
        char            *name;          /* mesh file name */
        int             nref;           /* reference count */
        int             ldflags;        /* what we've loaded */
        CUBE            mcube;          /* bounds and octree */
        FLOAT           uvlim[2][2];    /* local coordinate extrema */
        MESHPATCH       *patch;         /* mesh patch list */
        int             npatches;       /* number of mesh patches */
        char            *cdata;         /* opaque client data pointer */
        struct mesh     *next;          /* next mesh in list */
} MESH;

/* A mesh instance */
typedef struct {
        FULLXF          x;              /* forward and backward transforms */
        MESH            *msh;           /* mesh object reference */
} MESHINST;

                                /* vertex flags */
#define MT_V            01
#define MT_N            02
#define MT_UV           04
#define MT_ALL          07

/* A mesh vertex */
typedef struct {
        int             fl;             /* setting flags */
        FVECT           v;              /* vertex location */
        FVECT           n;              /* vertex normal */
        FLOAT           uv[2];          /* local coordinates */
} MESHVERT;

                                /* mesh format identifier */
#define MESHFMT         "Radiance_tmesh"
                                /* magic number for mesh files */
#define MESHMAGIC       ( 0 *MAXOBJSIZ+311)     /* increment first value */

#ifdef NOPROTO

extern MESH     *getmesh();
extern INSTANCE *getmeshinst();
extern int      getmeshtrivid();
extern int      getmeshvert();
extern int      getmeshtri();
extern int4     addmeshvert();
extern OBJECT   addmeshtri();
extern void     printmeshstats();
extern void     freemesh();
extern void     freemeshinst();
extern void     readmesh();
extern void     writemesh();

#else

extern MESH     *getmesh(char *mname, int flags);
extern MESHINST *getmeshinst(OBJREC *o, int flags);
extern int      getmeshtrivid(int4 tvid[3], MESH *mp, OBJECT ti);
extern int      getmeshvert(MESHVERT *vp, MESH *mp, int4 vid, int what);
extern int      getmeshtri(MESHVERT tv[3], MESH *mp, OBJECT ti, int what);
extern int4     addmeshvert(MESH *mp, MESHVERT *vp);
extern OBJECT   addmeshtri(MESH *mp, MESHVERT tv[3]);
extern void     printmeshstats(MESH *ms, FILE *fp);
extern void     freemesh(MESH *ms);
extern void     freemeshinst(OBJREC *o);
extern void     readmesh(MESH *mp, char *path, int flags);
extern void     writemesh(MESH *mp, FILE *fp);

#endif /* NOPROTO */
Revision:	2.1
Committed:	Tue Mar 11 17:08:55 2003 UTC (21 years, 1 month ago) by greg
Content type:	text/plain
Branch:	MAIN
Log Message:	First working version of new "mesh" primitive, obj2mesh converter
#	User	Rev	Content
1	greg	2.1	/* RCSid $Id$ */
2			/*
3			* Header for compact triangle mesh geometry
4			*
5			* Include after standard.h, object.h and octree.h
6			*/
7
8			#include "copyright.h"
9
10			#ifndef uint4
11			#define uint4 unsigned int4
12			#endif
13			#ifndef BYTE
14			#define BYTE unsigned char
15			#endif
16
17			/*
18			* Vertex space is minimized without compromising accuracy by using a
19			* 4-byte unsigned int to indicate position in the enclosing octree cube.
20			* The same trick is used for any local (u,v) coordinates, whose limits
21			* are recorded separately in the parent MESH structure. The uvlimit's
22			* in the MESH structure are set such that (0,0) is out of range, so
23			* we use this to indicate an unspecified local coordinate.
24			* A vertex normal, if specified, is stored in a single 4-byte
25			* integer using the codec in dircode.c. The encodedir() function
26			* never generates 0, so we can use this for unspecified normals.
27			*
28			* Vertex ID's are encoded using the bottom 8 bits of a 4-byte integer
29			* to index a vertex in a patch indicated by the 20 bits above (9-29).
30			* For triangle ID's, the top 10 bits (11-31) indicate the patch, and
31			* the 10th bit indicates whether the triangle joins patches.
32			* If not, then the bottom 9 bits index into the local PTri array.
33			* If it's a joiner, then the 9th bit indicates whether the triangle joins
34			* two patches, in which case the bottom 8 bits index the PJoin2 array.
35			* Otherwise, the bottom 8 bits index the PJoin1 array.
36			*
37			* These shenanigans minimize vertex reference memory requirements
38			* in compiled mesh structures, where the octree leaves contain sets
39			* of triangle ID's rather than the more usual objects. It seems like
40			* a lot of effort, but it can reduce mesh storage by a factor of 3
41			* or more. This is important, as the whole point is to model very
42			* complicated geometry with this structure, and memory is the main
43			* limitation. (We also optimize intersection tests for triangles.)
44			*/
45
46			/* A triangle mesh patch */
47			typedef struct {
48			uint4 (xyz)[3]; / up to 256 patch vertices */
49			int4 norm; / vertex normals */
50			uint4 (uv)[2]; / vertex local coordinates */
51			struct PTri {
52			BYTE v1, v2, v3; /* local vertices */
53			} tri; / local triangles */
54			struct PJoin1 {
55			int4 v1j; /* non-local vertex */
56			BYTE v2, v3; /* local vertices */
57			} j1tri; / joiner triangles */
58			struct PJoin2 {
59			int4 v1j, v2j; /* non-local vertices */
60			BYTE v3; /* local vertex */
61			} j2tri; / double joiner triangles */
62			short nverts; /* vertex count */
63			short ntris; /* triangle count */
64			short nj1tris; /* joiner triangle count */
65			short nj2tris; /* double joiner triangle count */
66			} MESHPATCH;
67
68			/* A loaded mesh */
69			typedef struct mesh {
70			char name; / mesh file name */
71			int nref; /* reference count */
72			int ldflags; /* what we've loaded */
73			CUBE mcube; /* bounds and octree */
74			FLOAT uvlim[2][2]; /* local coordinate extrema */
75			MESHPATCH patch; / mesh patch list */
76			int npatches; /* number of mesh patches */
77			char cdata; / opaque client data pointer */
78			struct mesh next; / next mesh in list */
79			} MESH;
80
81			/* A mesh instance */
82			typedef struct {
83			FULLXF x; /* forward and backward transforms */
84			MESH msh; / mesh object reference */
85			} MESHINST;
86
87			/* vertex flags */
88			#define MT_V 01
89			#define MT_N 02
90			#define MT_UV 04
91			#define MT_ALL 07
92
93			/* A mesh vertex */
94			typedef struct {
95			int fl; /* setting flags */
96			FVECT v; /* vertex location */
97			FVECT n; /* vertex normal */
98			FLOAT uv[2]; /* local coordinates */
99			} MESHVERT;
100
101			/* mesh format identifier */
102			#define MESHFMT "Radiance_tmesh"
103			/* magic number for mesh files */
104			#define MESHMAGIC ( 0 MAXOBJSIZ+311) / increment first value */
105
106			#ifdef NOPROTO
107
108			extern MESH *getmesh();
109			extern INSTANCE *getmeshinst();
110			extern int getmeshtrivid();
111			extern int getmeshvert();
112			extern int getmeshtri();
113			extern int4 addmeshvert();
114			extern OBJECT addmeshtri();
115			extern void printmeshstats();
116			extern void freemesh();
117			extern void freemeshinst();
118			extern void readmesh();
119			extern void writemesh();
120
121			#else
122
123			extern MESH getmesh(char mname, int flags);
124			extern MESHINST getmeshinst(OBJREC o, int flags);
125			extern int getmeshtrivid(int4 tvid[3], MESH *mp, OBJECT ti);
126			extern int getmeshvert(MESHVERT vp, MESH mp, int4 vid, int what);
127			extern int getmeshtri(MESHVERT tv[3], MESH *mp, OBJECT ti, int what);
128			extern int4 addmeshvert(MESH mp, MESHVERT vp);
129			extern OBJECT addmeshtri(MESH *mp, MESHVERT tv[3]);
130			extern void printmeshstats(MESH ms, FILE fp);
131			extern void freemesh(MESH *ms);
132			extern void freemeshinst(OBJREC *o);
133			extern void readmesh(MESH mp, char path, int flags);
134			extern void writemesh(MESH mp, FILE fp);
135
136			#endif /* NOPROTO */