--- ray/src/gen/illum.cal	1991/11/12 17:05:10	2.1
+++ ray/src/gen/illum.cal	1992/08/10 15:55:12	2.2
@@ -3,22 +3,45 @@
 {
 	Coordinate computations for mkillum output.
 
-	There are no arguments for the spherical case:
+	For the spherical case, A1-A3 is the value at the positive pole,
+	A4-A6 is the value at the negative pole, and A7 is the pole influence:
 
 	il_alt		- Altitude (1 to -1) for spherical coordinates
 	il_azi		- Azimuth (0 to 2*PI) for sphere
 
-	For the hemispherical case, A1-A9 are the unit vectors for the
+	For the hemispherical case, A1-A3 and A4 are the pole value and
+	influence, respectively, and A5-A13 are the unit vectors for the
 	hemisphere's coordinate system:
 
 	il_alth		- Altitude (1 to 0) for hemispherical coordinates
 	il_azih		- Azimuth (0 to 2*PI) for hemisphere
 }
 
+norm_rad(r) : if( r, r, r+2*PI );
+					{ sphere coordinates }
 il_alt = Dz;
 il_azi = norm_rad(atan2(Dy, Dx));
 
-il_alth = sq(-Dx*A7-Dy*A8-Dz*A9);
-il_azih = norm_rad(atan2(-Dx*A4-Dy*A5-Dz*A6, -Dx*A1-Dy*A2-Dz*A3));
+s_val(v, vN, vS) = noneg(if( il_alt-A7,
+			linterp((il_alt-A7)/(1-A7), v, vN),
+			if ( -il_alt-A7,
+				linterp((-il_alt-A7)/(1-A7), v, vS),
+				v ),
+			v ));
+					{ sphere values }
+s_red(r,g,b) = s_val(r, A1, A4);
+s_grn(r,g,b) = s_val(g, A2, A5);
+s_blu(r,g,b) = s_val(b, A3, A6);
+s_gry(r,g,b) = s_val(grey(r,g,b), grey(A1,A2,A3), grey(A4,A5,A6));
 
-norm_rad(r) = if( r, r, r+2*PI );
+					{ hemisphere coordinates }
+il_alth = sq(-Dx*arg(11)-Dy*arg(12)-Dz*arg(13));
+il_azih = norm_rad(atan2(-Dx*arg(8)-Dy*arg(9)-Dz*arg(10),
+			-Dx*arg(5)-Dy*arg(6)-Dz*arg(7)));
+
+h_val(v, vN) = noneg(if( il_alth-A4, linterp((il_alth-A4)/(1-A4), v, vN), v ));
+					{ hemisphere values }
+h_red(r,g,b) = h_val(r, A1);
+h_grn(r,g,b) = h_val(g, A2);
+h_blu(r,g,b) = h_val(b, A3);
+h_gry(r,g,b) = h_val(grey(r,g,b), grey(A1,A2,A3));