--- ray/src/cv/source.cal	1991/10/15 13:09:46	1.2
+++ ray/src/cv/source.cal	1993/04/05 16:40:10	2.6
@@ -3,26 +3,37 @@
 {
 	Source distribution coordinates (degrees).
 
-	Theta is measured from the negative z-axis,
-	phi is measured from the positive x-axis
-	according to the right-hand rule.
+	Theta is measured from the negative z-axis.
+	Phi is measured from the positive x-axis (0 degrees)
+		towards the negative y-axis (90 degrees).
 
 	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.
+	The dimensions of the box, which must be aligned with
+	the x,y,z axes, are given in meters regardless of the
+	units being used in the scene file.
+
 	A1		- optional multipier
-	A2,A3,A4	- X,Y,Z dimensions of axis-aligned box
+	A2,A3,A4	- X,Y,Z dimensions of axis-aligned box (in meters!)
 }
 					{ 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 }
+src_phi = mod( atan2(Dy, -Dx) / DEGREE, 360 );	{ 0-360 }
 				{ bilateral symmetry }
 src_phi2 = tri( src_phi, 180 );		{ 0-180 }
 				{ quadrilateral symmetry }
@@ -31,5 +42,6 @@ src_phi4 = tri( src_phi, 90 );		{ 0-90 }
 				{ Type B photometry coordinates }
 srcB_vert = atan( -Dx/Dz ) / DEGREE;
 srcB_horiz = Asin(Dy) / DEGREE;
-				{ w/ bilateral symmetry }
+				{ w/ symmetry }
+srcB_vert2 = abs( srcB_vert );
 srcB_horiz2 = abs( srcB_horiz );