src/common/bsdf.h

/* RCSid $Id: bsdf.h,v 2.27 2020/05/14 19:20:13 greg Exp $ */
/*
 *  bsdf.h
 *  
 *  Declarations for bidirectional scattering distribution functions.
 *  Assumes <stdio.h> already included.
 *
 *  A material is oriented in right-hand coordinate system with X-axis
 *      in the surface plane pointed to the right as seen from the front.
 *      This means the Y-axis is "up" and the Z-axis is the surface normal.
 *
 *  Note that we reverse the identification of "front" and "back" from
 *      the conventions used in WINDOW 6.  "Front" in our library points
 *      in the +Z direction, towards the interior of the space rather
 *      than the exterior.
 *
 *  BSDF incident & exiting vectors are always oriented away from surface.
 *
 *  Created by Greg Ward on 1/10/11.
 *
 */

#ifndef _BSDF_H_
#define _BSDF_H_

#include "fvect.h"
#include "ccolor.h"
#include "platform.h"

#ifdef __cplusplus
extern "C" {
#endif

#define SDnameLn        128             /* maximum BSDF name length */
#define SDmaxCh         3               /* maximum # spectral channels */

/* Component flags for SDsampBSDF() and SDdirectHemi() */
#define SDsampR         0x1             /* include reflection */
#define SDsampT         0x2             /* include transmission */
#define SDsampS         0x3             /* include scattering (R+T) */
#define SDsampSp        0x4             /* include non-diffuse portion */
#define SDsampDf        0x8             /* include diffuse portion */
#define SDsampSpR       0x5             /* include non-diffuse reflection */
#define SDsampSpT       0x6             /* include non-diffuse transmission */
#define SDsampSpS       0x7             /* include non-diffuse scattering */
#define SDsampAll       0xF             /* include everything */

/* Projected solid angle query flags for SDsizeBSDF() */
#define SDqueryVal      0x0             /* query single value */
#define SDqueryMin      0x1             /* query minimum proj. solid angle */
#define SDqueryMax      0x2             /* query maximum proj. solid angle */

/* Error codes: normal return, out of memory, file i/o, file format, bad argument,
                 bad data, unsupported feature, internal error, unknown error */
typedef enum {SDEnone=0, SDEmemory, SDEfile, SDEformat, SDEargument,
                SDEdata, SDEsupport, SDEinternal, SDEunknown} SDError;

/* English strings corresponding to ennumerated errors */
extern const char       *SDerrorEnglish[];

/* Pointer to error list in preferred language */
extern const char       **SDerrorList;

/* Additional information on last error (generally in English) */
extern char             SDerrorDetail[];

/* Holder for BSDF value and spectral color */
typedef struct {
        double          cieY;           /* photopic BSDF (Y) value */
        C_COLOR         spec;           /* spectral and (x,y) color */
} SDValue;

/* Cached, encoded, cumulative distribution for one incident (solid) angle */
#define SD_CDIST_BASE(styp)     double          cTotal; \
                                struct styp     *next
typedef struct SDCDst_s {
        SD_CDIST_BASE(SDCDst_s);        /* base fields first */
        /* ...encoded distribution extends struct */
} SDCDst;

extern const SDCDst     SDemptyCD;      /* empty distribution */

/* Forward declaration of BSDF component */
typedef struct SDComp_s SDComponent;

/* Methods needed to handle BSDF components (nothing is optional) */
typedef struct {
                                        /* return non-diffuse BSDF */
        int             (*getBSDFs)(float coef[SDmaxCh], const FVECT outVec,
                                    const FVECT inVec, SDComponent *sdc);
                                        /* query non-diffuse PSA for vector */
        SDError         (*queryProjSA)(double *psa, const FVECT v1,
                                                const RREAL *v2, int qflags,
                                                SDComponent *sdc);
                                        /* get cumulative distribution */
        const SDCDst    *(*getCDist)(const FVECT inVec, SDComponent *sdc);
                                        /* sample cumulative distribution */
        SDError         (*sampCDist)(FVECT ioVec, double randX,
                                                const SDCDst *cdp);
                                        /* free a spectral BSDF component */
        void            (*freeSC)(void *dist);
} SDFunc;

/* Structure to hold a spectral BSDF component (typedef SDComponent above) */
struct SDComp_s {
        C_COLOR         cspec[SDmaxCh]; /* component spectral bases */
        const SDFunc    *func;          /* methods for this component */
        void            *dist;          /* loaded distribution data */
        SDCDst          *cdList;        /* cumulative distribution cache */
};

/* Container for non-diffuse BSDF components */
typedef struct {
        double          minProjSA;      /* minimum projected solid angle */
        double          maxHemi;        /* maximum directional hemispherical */
        int             ncomp;          /* number of separate components */
        SDComponent     comp[1];        /* BSDF components (extends struct) */
} SDSpectralDF;

/* Loaded BSDF data */
typedef struct {
        char            name[SDnameLn]; /* BSDF name (usu. derived from file) */
        char            matn[SDnameLn]; /* material name */
        char            makr[SDnameLn]; /* manufacturer */
        char            *mgf;           /* geometric description (if any) */
        double          dim[3];         /* width, height, thickness (meters) */
        SDValue         rLambFront;     /* diffuse front reflectance */
        SDValue         rLambBack;      /* diffuse rear reflectance */
        SDValue         tLambFront;     /* diffuse front transmittance */
        SDValue         tLambBack;      /* diffuse back transmittance */
        SDSpectralDF    *rf, *rb;       /* non-diffuse BRDF components */
        SDSpectralDF    *tf, *tb;       /* non-diffuse BTDF components */
} SDData;

/* List of loaded BSDFs */
extern struct SDCache_s {
        SDData          bsdf;           /* BSDF data */
        unsigned        refcnt;         /* how many callers are using us? */
        struct SDCache_s                /* next in cache list */
                        *next;
} *SDcacheList;         /* Global BSDF cache */

/* BSDF cache retention policies */
#define SDretainNone    0               /* free unreferenced BSDF data */
#define SDretainBSDFs   1               /* keep loaded BSDFs in memory */
#define SDretainAll     2               /* also keep cumulative cache data */

extern int              SDretainSet;    /* =SDretainNone by default */
extern unsigned long    SDmaxCache;     /* =0 (unlimited) by default */

/*****************************************************************
 * The following routines are less commonly used by applications.
 */

#define SDisLoaded(sd)  ((sd)->rLambFront.spec.flags != 0)

/* Report an error to the indicated stream */
extern SDError          SDreportError(SDError ec, FILE *fp);

/* Shorten file path to useable BSDF name, removing suffix */
extern void             SDclipName(char res[SDnameLn], const char *fname);

/* Allocate new spectral distribution function */
extern SDSpectralDF     *SDnewSpectralDF(int nc);

/* Add component(s) to spectral distribution function */
extern SDSpectralDF     *SDaddComponent(SDSpectralDF *odf, int nadd);

/* Free a spectral distribution function */
extern void             SDfreeSpectralDF(SDSpectralDF *df);

/* Initialize an unused BSDF struct and assign name (calls SDclipName) */
extern void             SDclearBSDF(SDData *sd, const char *fname);

/* Load a BSDF struct from the given file (keeps name unchanged) */
extern SDError          SDloadFile(SDData *sd, const char *fname);

/* Free data associated with BSDF struct */
extern void             SDfreeBSDF(SDData *sd);

/* Find writeable BSDF by name, or allocate new cache entry if absent */
extern SDData           *SDgetCache(const char *bname);

/* Free cached cumulative distributions for BSDF component */
extern void             SDfreeCumulativeCache(SDSpectralDF *df);

/* Sample an individual BSDF component */
extern SDError          SDsampComponent(SDValue *sv, FVECT ioVec,
                                        double randX, SDComponent *sdc);

/* Convert 1-dimensional random variable to N-dimensional */
extern void             SDmultiSamp(double t[], int n, double randX);

/* Map a [0,1]^2 square to a unit radius disk */
extern void             SDsquare2disk(double ds[2], double seedx, double seedy);

/* Map point on unit disk to a unit square in [0,1]^2 range */
extern void             SDdisk2square(double sq[2], double diskx, double disky);

/*****************************************************************
 * The calls below are the ones most applications require.
 * All directions are assumed to be unit vectors.
 */

/* Get BSDF from cache (or load and cache it on first call) */
/* Report any problems to stderr, return NULL on failure */
extern const SDData     *SDcacheFile(const char *fname);

/* Free a BSDF from our cache (clear all if sd==NULL) */
extern void             SDfreeCache(const SDData *sd);

/* Query projected solid angle resolution for non-diffuse BSDF direction(s) */
extern SDError          SDsizeBSDF(double *projSA, const FVECT v1,
                                        const RREAL *v2, int qflags,
                                        const SDData *sd);

/* Return BSDF for the given incident and scattered ray vectors */
extern SDError          SDevalBSDF(SDValue *sv, const FVECT outVec,
                                        const FVECT inVec, const SDData *sd);

/* Compute directional hemispherical scattering at given incident angle */
extern double           SDdirectHemi(const FVECT inVec,
                                        int sflags, const SDData *sd);

/* Sample BSDF direction based on the given random variable */
extern SDError          SDsampBSDF(SDValue *sv, FVECT ioVec, double randX,
                                        int sflags, const SDData *sd);

/*****************************************************************
 * Vector math for getting between world and local BSDF coordinates.
 * Directions may be passed unnormalized to these routines.
 */

/* Compute World->BSDF transform from surface normal and BSDF up vector */
extern SDError          SDcompXform(RREAL vMtx[3][3], const FVECT sNrm,
                                        const FVECT uVec);

/* Compute inverse transform */
extern SDError          SDinvXform(RREAL iMtx[3][3], RREAL vMtx[3][3]);

/* Transform and normalize direction (column) vector */
extern SDError          SDmapDir(FVECT resVec, RREAL vMtx[3][3],
                                        const FVECT inpVec);

/* Application-specific BSDF loading routine (not part of our library) */
extern SDData           *loadBSDF(char *name);

/* Application-specific BSDF error translator (not part of our library) */
extern char             *transSDError(SDError ec);

#ifdef __cplusplus
}
#endif
#endif  /* ! _BSDF_H_ */
Revision:	2.28
Committed:	Sat Mar 27 17:50:18 2021 UTC (3 years, 1 month ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.27:	+3 -2 lines
Log Message:	fix: Allow different front/back diffuse reflectance in BSDF library
#	User	Rev	Content
1	greg	2.28	/* RCSid $Id: bsdf.h,v 2.27 2020/05/14 19:20:13 greg Exp $ */
2	greg	2.4	/*
3			* bsdf.h
4			*
5			* Declarations for bidirectional scattering distribution functions.
6			* Assumes <stdio.h> already included.
7			*
8			* A material is oriented in right-hand coordinate system with X-axis
9			* in the surface plane pointed to the right as seen from the front.
10			* This means the Y-axis is "up" and the Z-axis is the surface normal.
11			*
12	greg	2.8	* Note that we reverse the identification of "front" and "back" from
13			* the conventions used in WINDOW 6. "Front" in our library points
14			* in the +Z direction, towards the interior of the space rather
15			* than the exterior.
16			*
17	greg	2.13	* BSDF incident & exiting vectors are always oriented away from surface.
18	greg	2.4	*
19			* Created by Greg Ward on 1/10/11.
20			*
21			*/
22
23			#ifndef _BSDF_H_
24			#define _BSDF_H_
25
26			#include "fvect.h"
27			#include "ccolor.h"
28	schorsch	2.24	#include "platform.h"
29	greg	2.4
30			#ifdef __cplusplus
31			extern "C" {
32			#endif
33
34			#define SDnameLn 128 /* maximum BSDF name length */
35			#define SDmaxCh 3 /* maximum # spectral channels */
36
37	greg	2.9	/* Component flags for SDsampBSDF() and SDdirectHemi() */
38	greg	2.4	#define SDsampR 0x1 /* include reflection */
39			#define SDsampT 0x2 /* include transmission */
40			#define SDsampS 0x3 /* include scattering (R+T) */
41			#define SDsampSp 0x4 /* include non-diffuse portion */
42			#define SDsampDf 0x8 /* include diffuse portion */
43			#define SDsampSpR 0x5 /* include non-diffuse reflection */
44			#define SDsampSpT 0x6 /* include non-diffuse transmission */
45			#define SDsampSpS 0x7 /* include non-diffuse scattering */
46			#define SDsampAll 0xF /* include everything */
47
48	greg	2.9	/* Projected solid angle query flags for SDsizeBSDF() */
49	greg	2.7	#define SDqueryVal 0x0 /* query single value */
50			#define SDqueryMin 0x1 /* query minimum proj. solid angle */
51			#define SDqueryMax 0x2 /* query maximum proj. solid angle */
52	greg	2.4
53			/* Error codes: normal return, out of memory, file i/o, file format, bad argument,
54			bad data, unsupported feature, internal error, unknown error */
55			typedef enum {SDEnone=0, SDEmemory, SDEfile, SDEformat, SDEargument,
56			SDEdata, SDEsupport, SDEinternal, SDEunknown} SDError;
57
58	greg	2.22	/* English strings corresponding to ennumerated errors */
59	greg	2.4	extern const char *SDerrorEnglish[];
60
61	greg	2.22	/* Pointer to error list in preferred language */
62			extern const char **SDerrorList;
63
64			/* Additional information on last error (generally in English) */
65	greg	2.4	extern char SDerrorDetail[];
66
67			/* Holder for BSDF value and spectral color */
68			typedef struct {
69			double cieY; /* photopic BSDF (Y) value */
70			C_COLOR spec; /* spectral and (x,y) color */
71			} SDValue;
72
73			/* Cached, encoded, cumulative distribution for one incident (solid) angle */
74	greg	2.16	#define SD_CDIST_BASE(styp) double cTotal; \
75			struct styp *next
76	greg	2.4	typedef struct SDCDst_s {
77	greg	2.16	SD_CDIST_BASE(SDCDst_s); /* base fields first */
78	greg	2.4	/* ...encoded distribution extends struct */
79			} SDCDst;
80
81	greg	2.19	extern const SDCDst SDemptyCD; /* empty distribution */
82
83	greg	2.4	/* Forward declaration of BSDF component */
84			typedef struct SDComp_s SDComponent;
85
86			/* Methods needed to handle BSDF components (nothing is optional) */
87	schorsch	2.25	typedef struct {
88	greg	2.4	/* return non-diffuse BSDF */
89			int (*getBSDFs)(float coef[SDmaxCh], const FVECT outVec,
90	greg	2.12	const FVECT inVec, SDComponent *sdc);
91	greg	2.4	/* query non-diffuse PSA for vector */
92	greg	2.11	SDError (queryProjSA)(double psa, const FVECT v1,
93			const RREAL *v2, int qflags,
94	greg	2.12	SDComponent *sdc);
95	greg	2.4	/* get cumulative distribution */
96			const SDCDst (getCDist)(const FVECT inVec, SDComponent *sdc);
97			/* sample cumulative distribution */
98	greg	2.12	SDError (*sampCDist)(FVECT ioVec, double randX,
99	greg	2.4	const SDCDst *cdp);
100			/* free a spectral BSDF component */
101			void (freeSC)(void dist);
102			} SDFunc;
103
104			/* Structure to hold a spectral BSDF component (typedef SDComponent above) */
105			struct SDComp_s {
106			C_COLOR cspec[SDmaxCh]; /* component spectral bases */
107	greg	2.26	const SDFunc func; / methods for this component */
108	greg	2.4	void dist; / loaded distribution data */
109			SDCDst cdList; / cumulative distribution cache */
110			};
111
112			/* Container for non-diffuse BSDF components */
113			typedef struct {
114			double minProjSA; /* minimum projected solid angle */
115			double maxHemi; /* maximum directional hemispherical */
116			int ncomp; /* number of separate components */
117			SDComponent comp[1]; /* BSDF components (extends struct) */
118			} SDSpectralDF;
119
120			/* Loaded BSDF data */
121			typedef struct {
122	greg	2.13	char name[SDnameLn]; /* BSDF name (usu. derived from file) */
123	greg	2.18	char matn[SDnameLn]; /* material name */
124			char makr[SDnameLn]; /* manufacturer */
125	greg	2.4	char mgf; / geometric description (if any) */
126	greg	2.23	double dim[3]; /* width, height, thickness (meters) */
127	greg	2.4	SDValue rLambFront; /* diffuse front reflectance */
128			SDValue rLambBack; /* diffuse rear reflectance */
129	greg	2.28	SDValue tLambFront; /* diffuse front transmittance */
130			SDValue tLambBack; /* diffuse back transmittance */
131	greg	2.19	SDSpectralDF rf, rb; /* non-diffuse BRDF components */
132			SDSpectralDF tf, tb; /* non-diffuse BTDF components */
133	greg	2.4	} SDData;
134
135			/* List of loaded BSDFs */
136			extern struct SDCache_s {
137			SDData bsdf; /* BSDF data */
138			unsigned refcnt; /* how many callers are using us? */
139			struct SDCache_s /* next in cache list */
140			*next;
141			} SDcacheList; / Global BSDF cache */
142
143	greg	2.14	/* BSDF cache retention policies */
144			#define SDretainNone 0 /* free unreferenced BSDF data */
145			#define SDretainBSDFs 1 /* keep loaded BSDFs in memory */
146	greg	2.4	#define SDretainAll 2 /* also keep cumulative cache data */
147
148	greg	2.13	extern int SDretainSet; /* =SDretainNone by default */
149	greg	2.27	extern unsigned long SDmaxCache; /* =0 (unlimited) by default */
150	greg	2.4
151			/*****************************************************************
152			* The following routines are less commonly used by applications.
153			*/
154
155	greg	2.6	#define SDisLoaded(sd) ((sd)->rLambFront.spec.flags != 0)
156	greg	2.4
157	greg	2.22	/* Report an error to the indicated stream */
158			extern SDError SDreportError(SDError ec, FILE *fp);
159	greg	2.4
160			/* Shorten file path to useable BSDF name, removing suffix */
161			extern void SDclipName(char res[SDnameLn], const char *fname);
162
163			/* Allocate new spectral distribution function */
164			extern SDSpectralDF *SDnewSpectralDF(int nc);
165
166	greg	2.17	/* Add component(s) to spectral distribution function */
167			extern SDSpectralDF SDaddComponent(SDSpectralDF odf, int nadd);
168
169	greg	2.4	/* Free a spectral distribution function */
170			extern void SDfreeSpectralDF(SDSpectralDF *df);
171
172	greg	2.10	/* Initialize an unused BSDF struct and assign name (calls SDclipName) */
173			extern void SDclearBSDF(SDData sd, const char fname);
174	greg	2.4
175			/* Load a BSDF struct from the given file (keeps name unchanged) */
176			extern SDError SDloadFile(SDData sd, const char fname);
177
178			/* Free data associated with BSDF struct */
179			extern void SDfreeBSDF(SDData *sd);
180
181			/* Find writeable BSDF by name, or allocate new cache entry if absent */
182			extern SDData SDgetCache(const char bname);
183
184			/* Free cached cumulative distributions for BSDF component */
185			extern void SDfreeCumulativeCache(SDSpectralDF *df);
186
187			/* Sample an individual BSDF component */
188	greg	2.12	extern SDError SDsampComponent(SDValue *sv, FVECT ioVec,
189			double randX, SDComponent *sdc);
190	greg	2.4
191			/* Convert 1-dimensional random variable to N-dimensional */
192			extern void SDmultiSamp(double t[], int n, double randX);
193
194			/* Map a [0,1]^2 square to a unit radius disk */
195	greg	2.21	extern void SDsquare2disk(double ds[2], double seedx, double seedy);
196	greg	2.4
197			/* Map point on unit disk to a unit square in [0,1]^2 range */
198	greg	2.21	extern void SDdisk2square(double sq[2], double diskx, double disky);
199	greg	2.4
200			/*****************************************************************
201			* The calls below are the ones most applications require.
202			* All directions are assumed to be unit vectors.
203			*/
204
205			/* Get BSDF from cache (or load and cache it on first call) */
206	greg	2.22	/* Report any problems to stderr, return NULL on failure */
207	greg	2.4	extern const SDData SDcacheFile(const char fname);
208
209	greg	2.13	/* Free a BSDF from our cache (clear all if sd==NULL) */
210	greg	2.4	extern void SDfreeCache(const SDData *sd);
211
212	greg	2.11	/* Query projected solid angle resolution for non-diffuse BSDF direction(s) */
213			extern SDError SDsizeBSDF(double *projSA, const FVECT v1,
214			const RREAL *v2, int qflags,
215			const SDData *sd);
216	greg	2.4
217			/* Return BSDF for the given incident and scattered ray vectors */
218			extern SDError SDevalBSDF(SDValue *sv, const FVECT outVec,
219			const FVECT inVec, const SDData *sd);
220
221			/* Compute directional hemispherical scattering at given incident angle */
222			extern double SDdirectHemi(const FVECT inVec,
223			int sflags, const SDData *sd);
224
225			/* Sample BSDF direction based on the given random variable */
226	greg	2.12	extern SDError SDsampBSDF(SDValue *sv, FVECT ioVec, double randX,
227	greg	2.4	int sflags, const SDData *sd);
228
229			/*****************************************************************
230			* Vector math for getting between world and local BSDF coordinates.
231			* Directions may be passed unnormalized to these routines.
232			*/
233
234	greg	2.13	/* Compute World->BSDF transform from surface normal and BSDF up vector */
235	greg	2.4	extern SDError SDcompXform(RREAL vMtx[3][3], const FVECT sNrm,
236			const FVECT uVec);
237
238			/* Compute inverse transform */
239			extern SDError SDinvXform(RREAL iMtx[3][3], RREAL vMtx[3][3]);
240
241			/* Transform and normalize direction (column) vector */
242			extern SDError SDmapDir(FVECT resVec, RREAL vMtx[3][3],
243			const FVECT inpVec);
244
245	greg	2.13	/* Application-specific BSDF loading routine (not part of our library) */
246	greg	2.5	extern SDData loadBSDF(char name);
247
248	greg	2.13	/* Application-specific BSDF error translator (not part of our library) */
249	greg	2.5	extern char *transSDError(SDError ec);
250
251	greg	2.4	#ifdef __cplusplus
252			}
253			#endif
254			#endif /* ! _BSDF_H_ */