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/* RCSid $Id: bsdf.h,v 2.29 2021/12/07 23:49:50 greg Exp $ */ |
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/* |
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* bsdf.h |
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* |
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* Declarations for bidirectional scattering distribution functions. |
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* Assumes <stdio.h> already included. |
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* |
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* A material is oriented in right-hand coordinate system with X-axis |
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* in the surface plane pointed to the right as seen from the front. |
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* This means the Y-axis is "up" and the Z-axis is the surface normal. |
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* |
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* Note that we reverse the identification of "front" and "back" from |
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* the conventions used in WINDOW 6. "Front" in our library points |
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* in the +Z direction, towards the interior of the space rather |
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* than the exterior. |
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* |
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* BSDF incident & exiting vectors are always oriented away from surface. |
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* |
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* Created by Greg Ward on 1/10/11. |
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* |
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*/ |
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|
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#ifndef _BSDF_H_ |
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#define _BSDF_H_ |
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|
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#include "fvect.h" |
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#include "ccolor.h" |
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#include "platform.h" |
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|
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#ifdef __cplusplus |
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extern "C" { |
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#endif |
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|
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#define SDnameLn 128 /* maximum BSDF name length */ |
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#define SDmaxCh 3 /* maximum # spectral channels */ |
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|
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/* Component flags for SDsampBSDF() and SDdirectHemi() */ |
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#define SDsampR 0x1 /* include reflection */ |
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#define SDsampT 0x2 /* include transmission */ |
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#define SDsampS 0x3 /* include scattering (R+T) */ |
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#define SDsampSp 0x4 /* include non-diffuse portion */ |
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#define SDsampDf 0x8 /* include diffuse portion */ |
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#define SDsampSpR 0x5 /* include non-diffuse reflection */ |
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#define SDsampSpT 0x6 /* include non-diffuse transmission */ |
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#define SDsampSpS 0x7 /* include non-diffuse scattering */ |
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#define SDsampAll 0xF /* include everything */ |
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|
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/* Projected solid angle query flags for SDsizeBSDF() */ |
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#define SDqueryVal 0x0 /* query single value */ |
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#define SDqueryMin 0x1 /* query minimum proj. solid angle */ |
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#define SDqueryMax 0x2 /* query maximum proj. solid angle */ |
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|
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/* Error codes: normal return, out of memory, file i/o, file format, bad argument, |
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bad data, unsupported feature, internal error, unknown error */ |
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typedef enum {SDEnone=0, SDEmemory, SDEfile, SDEformat, SDEargument, |
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SDEdata, SDEsupport, SDEinternal, SDEunknown} SDError; |
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|
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/* English strings corresponding to ennumerated errors */ |
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extern const char *SDerrorEnglish[]; |
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|
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/* Pointer to error list in preferred language */ |
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extern const char **SDerrorList; |
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|
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/* Additional information on last error (generally in English) */ |
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extern char SDerrorDetail[]; |
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|
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/* Holder for BSDF value and spectral color */ |
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typedef struct { |
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double cieY; /* photopic BSDF (Y) value */ |
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C_COLOR spec; /* spectral and (x,y) color */ |
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} SDValue; |
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|
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/* Cached, encoded, cumulative distribution for one incident (solid) angle */ |
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#define SD_CDIST_BASE(styp) double cTotal; \ |
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struct styp *next |
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typedef struct SDCDst_s { |
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SD_CDIST_BASE(SDCDst_s); /* base fields first */ |
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/* ...encoded distribution extends struct */ |
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} SDCDst; |
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|
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extern const SDCDst SDemptyCD; /* empty distribution */ |
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|
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/* Forward declaration of BSDF component */ |
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typedef struct SDComp_s SDComponent; |
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|
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/* Methods needed to handle BSDF components (nothing is optional) */ |
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typedef struct { |
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/* return non-diffuse BSDF */ |
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int (*getBSDFs)(float coef[SDmaxCh], const FVECT inVec, |
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const FVECT outVec, SDComponent *sdc); |
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/* query non-diffuse PSA for vector */ |
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SDError (*queryProjSA)(double *psa, const FVECT v1, |
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const RREAL *v2, int qflags, |
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SDComponent *sdc); |
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/* get cumulative distribution */ |
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const SDCDst *(*getCDist)(const FVECT inVec, SDComponent *sdc); |
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/* sample cumulative distribution */ |
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SDError (*sampCDist)(FVECT ioVec, double randX, |
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const SDCDst *cdp); |
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/* free a spectral BSDF component */ |
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void (*freeSC)(void *dist); |
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} SDFunc; |
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|
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/* Structure to hold a spectral BSDF component (typedef SDComponent above) */ |
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struct SDComp_s { |
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C_COLOR cspec[SDmaxCh]; /* component spectral bases */ |
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const SDFunc *func; /* methods for this component */ |
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void *dist; /* loaded distribution data */ |
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SDCDst *cdList; /* cumulative distribution cache */ |
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}; |
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|
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/* Container for non-diffuse BSDF components */ |
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typedef struct { |
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double minProjSA; /* minimum projected solid angle */ |
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double maxHemi; /* maximum directional hemispherical */ |
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int ncomp; /* number of separate components */ |
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SDComponent comp[1]; /* BSDF components (extends struct) */ |
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} SDSpectralDF; |
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|
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/* Loaded BSDF data */ |
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typedef struct { |
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char name[SDnameLn]; /* BSDF name (usu. derived from file) */ |
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char matn[SDnameLn]; /* material name */ |
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char makr[SDnameLn]; /* manufacturer */ |
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char *mgf; /* geometric description (if any) */ |
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double dim[3]; /* width, height, thickness (meters) */ |
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SDValue rLambFront; /* diffuse front reflectance */ |
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SDValue rLambBack; /* diffuse rear reflectance */ |
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SDValue tLambFront; /* diffuse front transmittance */ |
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SDValue tLambBack; /* diffuse back transmittance */ |
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SDSpectralDF *rf, *rb; /* non-diffuse BRDF components */ |
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SDSpectralDF *tf, *tb; /* non-diffuse BTDF components */ |
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} SDData; |
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|
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/* List of loaded BSDFs */ |
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extern struct SDCache_s { |
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SDData bsdf; /* BSDF data */ |
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unsigned refcnt; /* how many callers are using us? */ |
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struct SDCache_s /* next in cache list */ |
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*next; |
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} *SDcacheList; /* Global BSDF cache */ |
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|
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/* BSDF cache retention policies */ |
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#define SDretainNone 0 /* free unreferenced BSDF data */ |
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#define SDretainBSDFs 1 /* keep loaded BSDFs in memory */ |
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#define SDretainAll 2 /* also keep cumulative cache data */ |
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|
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extern int SDretainSet; /* =SDretainNone by default */ |
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extern unsigned long SDmaxCache; /* =0 (unlimited) by default */ |
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|
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/***************************************************************** |
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* The following routines are less commonly used by applications. |
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*/ |
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|
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#define SDisLoaded(sd) ((sd)->rLambFront.spec.flags != 0) |
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|
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/* Report an error to the indicated stream */ |
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extern SDError SDreportError(SDError ec, FILE *fp); |
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|
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/* Shorten file path to useable BSDF name, removing suffix */ |
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extern void SDclipName(char res[SDnameLn], const char *fname); |
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|
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/* Allocate new spectral distribution function */ |
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extern SDSpectralDF *SDnewSpectralDF(int nc); |
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|
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/* Add component(s) to spectral distribution function */ |
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extern SDSpectralDF *SDaddComponent(SDSpectralDF *odf, int nadd); |
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|
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/* Free a spectral distribution function */ |
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extern void SDfreeSpectralDF(SDSpectralDF *df); |
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|
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/* Initialize an unused BSDF struct and assign name (calls SDclipName) */ |
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extern void SDclearBSDF(SDData *sd, const char *fname); |
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|
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/* Load a BSDF struct from the given file (keeps name unchanged) */ |
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extern SDError SDloadFile(SDData *sd, const char *fname); |
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|
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/* Free data associated with BSDF struct */ |
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extern void SDfreeBSDF(SDData *sd); |
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|
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/* Find writeable BSDF by name, or allocate new cache entry if absent */ |
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extern SDData *SDgetCache(const char *bname); |
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|
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/* Free cached cumulative distributions for BSDF component */ |
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extern void SDfreeCumulativeCache(SDSpectralDF *df); |
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|
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/* Sample an individual BSDF component */ |
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extern SDError SDsampComponent(SDValue *sv, FVECT ioVec, |
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double randX, SDComponent *sdc); |
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|
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/* Convert 1-dimensional random variable to N-dimensional */ |
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extern void SDmultiSamp(double t[], int n, double randX); |
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|
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/***************************************************************** |
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* The calls below are the ones most applications require. |
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* All directions are assumed to be unit vectors. |
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*/ |
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|
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/* Get BSDF from cache (or load and cache it on first call) */ |
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/* Report any problems to stderr, return NULL on failure */ |
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extern const SDData *SDcacheFile(const char *fname); |
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|
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/* Free a BSDF from our cache (clear all if sd==NULL) */ |
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extern void SDfreeCache(const SDData *sd); |
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|
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/* Query projected solid angle resolution for non-diffuse BSDF direction(s) */ |
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extern SDError SDsizeBSDF(double *projSA, const FVECT v1, |
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const RREAL *v2, int qflags, |
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const SDData *sd); |
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|
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/* Return BSDF for the given incident and scattered ray vectors */ |
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extern SDError SDevalBSDF(SDValue *sv, const FVECT inVec, |
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const FVECT outVec, const SDData *sd); |
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|
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/* Compute directional hemispherical scattering at given incident angle */ |
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extern double SDdirectHemi(const FVECT inVec, |
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int sflags, const SDData *sd); |
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|
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/* Sample BSDF direction based on the given random variable */ |
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extern SDError SDsampBSDF(SDValue *sv, FVECT ioVec, double randX, |
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int sflags, const SDData *sd); |
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|
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/***************************************************************** |
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* Vector math for getting between world and local BSDF coordinates. |
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* Directions may be passed unnormalized to these routines. |
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*/ |
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|
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/* Compute World->BSDF transform from surface normal and BSDF up vector */ |
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extern SDError SDcompXform(RREAL vMtx[3][3], const FVECT sNrm, |
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const FVECT uVec); |
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|
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/* Compute inverse transform */ |
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extern SDError SDinvXform(RREAL iMtx[3][3], RREAL vMtx[3][3]); |
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|
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/* Transform and normalize direction (column) vector */ |
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extern SDError SDmapDir(FVECT resVec, RREAL vMtx[3][3], |
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const FVECT inpVec); |
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|
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/* Application-specific BSDF loading routine (not part of our library) */ |
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extern SDData *loadBSDF(char *name); |
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|
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/* Application-specific BSDF error translator (not part of our library) */ |
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extern char *transSDError(SDError ec); |
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|
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#ifdef __cplusplus |
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} |
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#endif |
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#endif /* ! _BSDF_H_ */ |
