- fixed: R_PointToAngle could overflow with very long vectors passed to

it. This caused rendering bugs on some maps. (Interestingly the only
  other port having a safeguard for this in place was PrBoom.)


SVN r1985 (trunk)

docs/rh-log.txt

@@ -1,4 +1,7 @@
 November 17, 2009  (Changes by Graf Zahl)
+- fixed: R_PointToAngle could overflow with very long vectors passed to 
+  it. This caused rendering bugs on some maps. (Interestingly the only
+  other port having a safeguard for this in place was PrBoom.)
 - reverted the change that makes 0-damage projectiles call P_DamageMobj.
   Both Hexen and Heretic depend on such projectiles not doing it as do many
   mods that create snow/rain effects plus any terrain splash mod.

src/r_main.cpp

@@ -264,6 +264,11 @@ angle_t R_PointToAngle2 (fixed_t x1, fixed_t y1, fixed_t x, fixed_t y)
 		return 0;
 	}
 
+	// We need to be aware of overflows here. If the values get larger than INT_MAX/4
+	// this code won't work anymore.
+
+	if (x < INT_MAX/4 && x > -INT_MAX/4 && y < INT_MAX/4 && y > -INT_MAX/4)
+	{
 		if (x >= 0)
 		{
 			if (y >= 0)
@@ -317,6 +322,14 @@ angle_t R_PointToAngle2 (fixed_t x1, fixed_t y1, fixed_t x, fixed_t y)
 				}
 			}
 		}
+	}
+	else
+	{
+		// we have to use the slower but more precise floating point atan2 function here.
+		// (use quickertoint to speed this up because the CRT's conversion is rather slow and
+		//  this is used in time critical code.)
+		return quickertoint((float)(atan2f(float(y-viewy), float(x-viewx)) * (ANGLE_180/M_PI)));
+	}
 }
 
 //==========================================================================