Changed: Also handle distMax with negative alpha in new manual rolloff function

--HG--
branch : sound_dev

code/nel/src/sound/driver/source.cpp

@@ -89,10 +89,18 @@ float ISource::computeManualRolloff(double alpha, float sqrdist, float distMin,
 			float rolloff = distMin / dist;
 			if (alpha <= -1.0f) return rolloff;
 
+			if (dist > distMax)
+			{
+				// full attenuation of mbrolloff
+				return (-alpha * rolloff);
+			}
+			else
+			{
 				double mb = mbMin * (dist - distMin) / (distMax - distMin);
 				float mbrolloff = (float)pow(10.0, (double)mb / 2000.0);
 				return ((1.0 + alpha) * mbrolloff - alpha * rolloff);
 			}
+		}
 		else
 		{
 			if (sqrdist > distMax * distMax)