Use better math constants

Author: illwieckz

src/engine/qcommon/q_shared.h

@@ -281,8 +281,16 @@ void  Com_Free_Aligned( void *ptr );
 #define M_SQRT2 1.414213562f
 #endif
 
-#ifndef M_ROOT3
-#define M_ROOT3 1.732050808f
+#ifndef M_RSQRT2
+#define M_RSQRT2 0.707106781f
+#endif
+
+#ifndef M_SQRT3
+#define M_SQRT3 1.732050808f
+#endif
+
+#ifndef M_RSQRT3
+#define M_RSQRT3 0.577350269f
 #endif
 
 #ifndef LINE_DISTANCE_EPSILON

src/engine/renderer/tr_shade_calc.cpp

@@ -495,7 +495,7 @@ static void AutospriteDeform( uint32_t numVertexes )
 		VectorCopy( backEnd.viewParms.orientation.axis[ 2 ], upDir );
 	}
 
-	float scale = 1.0 / M_SQRT2;
+	float scale = M_RSQRT2;
 
 	if ( backEnd.currentEntity->e.nonNormalizedAxes )
 	{