--- ray/src/common/depthcodec.c	2020/01/10 01:02:14	2.6
+++ ray/src/common/depthcodec.c	2021/01/26 18:47:25	2.11
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: depthcodec.c,v 2.6 2020/01/10 01:02:14 greg Exp $";
+static const char RCSid[] = "$Id: depthcodec.c,v 2.11 2021/01/26 18:47:25 greg Exp $";
 #endif
 /*
  * Routines to encode/decoded 16-bit depths
@@ -26,7 +26,7 @@ depth2code(double d, double dref)
 	if (d > dref)
 		return (int)(32768.001 - 32768.*dref/d) - 1;
 
-	return (int)(32767.*d/dref - 32768.);
+	return (int)(32767.*d/dref - 32768.999);
 }
 #endif
 
@@ -42,10 +42,10 @@ code2depth(int c, double dref)
 	if (c >= 32767)
 		return FHUGE;
 
-	if (c >= 0)
+	if (c >= -1)
 		return dref*32768./(32766.5 - c);
 
-	return dref*(32767.5 + c)*(1./32767.);
+	return dref*(32768.5 + c)*(1./32767.);
 }
 #endif
 
@@ -97,6 +97,8 @@ headline(char *s, void *p)
 			}
 			return -1;
 		}
+		if (dcp->hdrflags & HF_ENCODE)
+			return 0;	/* will add this later */
 	} else if (!strncmp(s, "SAMP360=", 8))
 		dcp->gotview--;
 	else if (isview(s))		/* get view params */
@@ -250,14 +252,18 @@ compute_worldpos(FVECT wpos, DEPTHCODEC *dcp, int x, i
 	RREAL	loc[2];
 	FVECT	rdir;
 
+	if (d >= FHUGE*.99)
+		goto badval;
+
 	pix2loc(loc, &dcp->res, x, y);
 
-	if (viewray(wpos, rdir, &dcp->vw, loc[0], loc[1]) < -FTINY) {
-		VCOPY(wpos, dcp->vw.vp);
-		return 0;
+	if (viewray(wpos, rdir, &dcp->vw, loc[0], loc[1]) >= -FTINY) {
+		VSUM(wpos, wpos, rdir, d);
+		return 1;
 	}
-	VSUM(wpos, wpos, rdir, d);
-	return 1;
+badval:
+	VCOPY(wpos, dcp->vw.vp);
+	return 0;
 }
 
 
@@ -317,6 +323,7 @@ seek_dc_pix(DEPTHCODEC *dcp, int x, int y)
 		return -1;
 	}
 	dcp->curpos = seekpos;
+	dcp->use_last = 0;
 	return 1;
 }