--- ray/src/cv/source.cal	1991/11/12 17:02:13	2.1
+++ ray/src/cv/source.cal	1992/03/03 15:01:45	2.2
@@ -10,16 +10,25 @@
 	srcB_vert and srcB_horiz are angles
 	used in type B photometry.
 
+	boxcorr function corrects for distribution modeled
+	with a rectangular box.  lboxcorr provides a more
+	accurate calculation for nearby surfaces, but requires
+	that the source box be centered at the origin.
+
 	A1		- optional multipier
 	A2,A3,A4	- X,Y,Z dimensions of axis-aligned box
 }
 					{ local definitions }
 norm_deg(d) : if( d, d, d+360 );
 boxprojection = abs(Dx)*A3*A4 + abs(Dy)*A2*A4 + abs(Dz)*A2*A3;
+lboxprojection = (	noneg(abs(Px-Dx*Ts)-A2/2)*A3*A4 +
+			noneg(abs(Py-Dy*Ts)-A3/2)*A2*A4 +
+			noneg(abs(Pz-Dz*Ts)-A4/2)*A2*A3 ) / Ts;
 
 flatcorr(v) = corr(v) / Rdot;		{ correction for flat sources }
 corr(v) = if(AC-.5, A1*v, v);		{ multiplier correction }
 boxcorr(v) = A1 * v / boxprojection;	{ correction for emitting box }
+lboxcorr(v) = A1 * v / lboxprojection;	{ local box correction }
 
 src_theta = Acos(Dz) / DEGREE;			{ 0-180 }
 src_phi = norm_deg( atan2(Dy, Dx) / DEGREE );	{ 0-360 }