--- ray/src/common/spec_rgb.c	1995/10/15 14:08:01	2.5
+++ ray/src/common/spec_rgb.c	1997/01/31 12:58:39	2.8
@@ -1,4 +1,4 @@
-/* Copyright (c) 1990 Regents of the University of California */
+/* Copyright (c) 1997 Regents of the University of California */
 
 #ifndef lint
 static char SCCSid[] = "$SunId$ LBL";
@@ -13,6 +13,9 @@ static char SCCSid[] = "$SunId$ LBL";
 
 RGBPRIMS  stdprims = STDPRIMS;		/* standard primary chromaticities */
 
+COLOR  cblack = BLKCOLOR;		/* global black color */
+COLOR  cwhite = WHTCOLOR;		/* global white color */
+
 /*
  *	The following table contains the CIE tristimulus integrals
  *  for X, Y, and Z.  The table is cumulative, so that
@@ -109,18 +112,67 @@ int  s, e;		/* starting and ending wavelengths */
 }
 
 
+cie_rgb(rgb, xyz)		/* convert CIE color to standard RGB */
+COLOR	rgb, xyz;
+{
+	colortrans(rgb, xyz2rgbmat, xyz);
+	clipgamut(rgb, xyz[CIEY], CGAMUT_LOWER, cblack, cwhite);
+}
+
+
+int
+clipgamut(col, brt, gamut, lower, upper)	/* clip to gamut cube */
+COLOR  col;
+double  brt;
+int  gamut;
+COLOR  lower, upper;
+{
+	int  rflags = 0;
+	double  brtmin, brtmax, v, vv;
+	COLOR  cgry;
+	register int  i;
+					/* check for no check */
+	if (gamut == 0) return(0);
+					/* check brightness limits */
+	brtmin = 1./3.*(lower[0]+lower[1]+lower[2]);
+	if (gamut & CGAMUT_LOWER && brt < brtmin) {
+		copycolor(col, lower);
+		return(CGAMUT_LOWER);
+	}
+	brtmax = 1./3.*(upper[0]+upper[1]+upper[2]);
+	if (gamut & CGAMUT_UPPER && brt > brtmax) {
+		copycolor(col, upper);
+		return(CGAMUT_UPPER);
+	}
+					/* compute equivalent grey */
+	v = (brt - brtmin)/(brtmax - brtmin);
+	for (i = 0; i < 3; i++)
+		cgry[i] = v*upper[i] + (1.-v)*lower[i];
+	vv = 1.;			/* check each limit */
+	for (i = 0; i < 3; i++)
+		if (gamut & CGAMUT_LOWER && col[i] < lower[i]) {
+			v = (lower[i] - cgry[i])/(col[i] - cgry[i]);
+			if (v < vv) vv = v;
+			rflags |= CGAMUT_LOWER;
+		} else if (gamut & CGAMUT_UPPER && col[i] > upper[i]) {
+			v = (upper[i] - cgry[i])/(col[i] - cgry[i]);
+			if (v < vv) vv = v;
+			rflags |= CGAMUT_UPPER;
+		}
+	if (rflags)			/* desaturate to cube face */
+		for (i = 0; i < 3; i++)
+			col[i] = vv*col[i] + (1.-vv)*cgry[i];
+	return(rflags);
+}
+
+
 colortrans(c2, mat, c1)		/* convert c1 by mat and put into c2 */
 register COLORMAT  mat;
 register COLOR  c1, c2;
 {
-	static float  cout[3];
-
-	cout[0] = mat[0][0]*c1[0] + mat[0][1]*c1[1] + mat[0][2]*c1[2];
-	cout[1] = mat[1][0]*c1[0] + mat[1][1]*c1[1] + mat[1][2]*c1[2];
-	cout[2] = mat[2][0]*c1[0] + mat[2][1]*c1[1] + mat[2][2]*c1[2];
-	if((c2[0] = cout[0]) < 0.) c2[0] = 0.;
-	if((c2[1] = cout[1]) < 0.) c2[1] = 0.;
-	if((c2[2] = cout[2]) < 0.) c2[2] = 0.;
+	c2[0] = mat[0][0]*c1[0] + mat[0][1]*c1[1] + mat[0][2]*c1[2];
+	c2[1] = mat[1][0]*c1[0] + mat[1][1]*c1[1] + mat[1][2]*c1[2];
+	c2[2] = mat[2][0]*c1[0] + mat[2][1]*c1[1] + mat[2][2]*c1[2];
 }
 
 
@@ -145,6 +197,10 @@ register RGBPRIMS  pr;
 {
 	double  C_rD, C_gD, C_bD;
 
+	if (pr == stdprims) {	/* can use xyz2rgbmat */
+		cpcolormat(mat, xyz2rgbmat);
+		return;
+	}
 	C_rD = (1./pr[WHT][CIEY]) *
 			( pr[WHT][CIEX]*(pr[GRN][CIEY] - pr[BLU][CIEY]) -
 			  pr[WHT][CIEY]*(pr[GRN][CIEX] - pr[BLU][CIEX]) +
@@ -191,6 +247,10 @@ register RGBPRIMS  pr;
 {
 	double  C_rD, C_gD, C_bD, D;
 
+	if (pr == stdprims) {	/* can use rgb2xyzmat */
+		cpcolormat(mat, rgb2xyzmat);
+		return;
+	}
 	C_rD = (1./pr[WHT][CIEY]) *
 			( pr[WHT][CIEX]*(pr[GRN][CIEY] - pr[BLU][CIEY]) -
 			  pr[WHT][CIEY]*(pr[GRN][CIEX] - pr[BLU][CIEX]) +
@@ -224,14 +284,14 @@ RGBPRIMS  pr1, pr2;
 {
 	COLORMAT  pr1toxyz, xyztopr2;
 
-	if (pr1 == stdprims)	/* can use rgb2xyzmat */
-		cpcolormat(pr1toxyz, rgb2xyzmat);
-	else			/* otherwise compute it */
-		comprgb2xyzmat(pr1toxyz, pr1);
-	if (pr2 == stdprims)	/* can use xyz2rgbmat */
-		cpcolormat(xyztopr2, xyz2rgbmat);
-	else			/* otherwise compute it */
-		compxyz2rgbmat(xyztopr2, pr2);
+	if (pr1 == pr2) {
+		mat[0][0] = mat[1][1] = mat[2][2] = 1.0;
+		mat[0][1] = mat[0][2] = mat[1][0] =
+		mat[1][2] = mat[2][0] = mat[2][1] = 0.0;
+		return;
+	}
+	comprgb2xyzmat(pr1toxyz, pr1);
+	compxyz2rgbmat(xyztopr2, pr2);
 				/* combine transforms */
 	multcolormat(mat, pr1toxyz, xyztopr2);
 }