--- ray/src/common/bsdf.h	2018/01/05 20:15:50	2.25
+++ ray/src/common/bsdf.h	2021/12/07 23:49:50	2.29
@@ -1,4 +1,4 @@
-/* RCSid $Id: bsdf.h,v 2.25 2018/01/05 20:15:50 schorsch Exp $ */
+/* RCSid $Id: bsdf.h,v 2.29 2021/12/07 23:49:50 greg Exp $ */
 /*
  *  bsdf.h
  *  
@@ -84,17 +84,10 @@ extern const SDCDst	SDemptyCD;	/* empty distribution *
 typedef struct SDComp_s	SDComponent;
 
 /* Methods needed to handle BSDF components (nothing is optional) */
-#ifdef __cplusplus
-/* in C++, the const puts the type into the local anonymous namespace,
-   making it a private (and different) type for each file using this header.
-*/
 typedef struct {
-#else
-typedef const struct {
-#endif
 					/* return non-diffuse BSDF */
-	int		(*getBSDFs)(float coef[SDmaxCh], const FVECT outVec,
-				    const FVECT inVec, SDComponent *sdc);
+	int		(*getBSDFs)(float coef[SDmaxCh], const FVECT inVec,
+				    const FVECT outVec, SDComponent *sdc);
 					/* query non-diffuse PSA for vector */
 	SDError		(*queryProjSA)(double *psa, const FVECT v1,
 						const RREAL *v2, int qflags,
@@ -111,7 +104,7 @@ typedef const struct {
 /* Structure to hold a spectral BSDF component (typedef SDComponent above) */
 struct SDComp_s {
 	C_COLOR		cspec[SDmaxCh];	/* component spectral bases */
-	SDFunc		*func;		/* methods for this component */
+	const SDFunc	*func;		/* methods for this component */
 	void		*dist;		/* loaded distribution data */
 	SDCDst		*cdList;	/* cumulative distribution cache */
 };
@@ -133,7 +126,8 @@ typedef struct {
 	double		dim[3];		/* width, height, thickness (meters) */
 	SDValue		rLambFront;	/* diffuse front reflectance */
 	SDValue		rLambBack;	/* diffuse rear reflectance */
-	SDValue		tLamb;		/* diffuse transmission */
+	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;
@@ -152,6 +146,7 @@ extern struct SDCache_s {
 #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.
@@ -220,8 +215,8 @@ extern SDError		SDsizeBSDF(double *projSA, const FVECT
 					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);
+extern SDError		SDevalBSDF(SDValue *sv, const FVECT inVec,
+					const FVECT outVec, const SDData *sd);
 
 /* Compute directional hemispherical scattering at given incident angle */
 extern double		SDdirectHemi(const FVECT inVec,