define explicit AREA_INVALID constant

tools/quake3/q3map2/portals.cpp

@@ -630,7 +630,7 @@ static int c_areas;
  */
 
 static void FloodAreas_r( node_t *node ){
-	if ( node->area != -1 ) {
+	if ( node->area != AREA_INVALID ) {
 		return;
 	}
 	if ( node->cluster == -1 ) {
@@ -678,7 +678,7 @@ static void FindAreas_r( node_t *node ){
 		return;
 	}
 
-	if ( node->opaque || node->area != -1 ) {
+	if ( node->opaque || node->area != AREA_INVALID ) {
 		return;
 	}
 
@@ -703,7 +703,7 @@ static void CheckAreas_r( const node_t *node ){
 	}
 
 	if ( node->cluster != -1 ) {
-		if ( node->area == -1 ) {
+		if ( node->area == AREA_INVALID ) {
 			Sys_Warning( "cluster %d has area set to -1\n", node->cluster );
 		}
 	}
@@ -717,7 +717,7 @@ static void CheckAreas_r( const node_t *node ){
  */
 
 static void FloodSkyboxArea_r( node_t *node ){
-	if ( skyboxArea < 0 ) {
+	if ( skyboxArea == AREA_INVALID ) {
 		return;
 	}
 

tools/quake3/q3map2/prtfile.cpp

@@ -274,7 +274,7 @@ static void NumberLeafs_r( node_t *node, int c ){
 		return;
 	}
 
-	node->area = -1;
+	node->area = AREA_INVALID;
 
 	if ( node->opaque ) {
 		// solid block, viewpoint never inside

tools/quake3/q3map2/q3map2.h

@@ -130,6 +130,7 @@
 #define CLIP_EPSILON            0.1f
 #define PLANESIDE_EPSILON       0.001f
 #define PLANENUM_LEAF           -1
+constexpr int AREA_INVALID    = -1;
 
 enum class EBrushType
 {
@@ -1891,7 +1892,7 @@ inline const Vector3b debugColors[ 12 ] =
 		{ 128, 192, 128 }
 	};
 
-inline int skyboxArea = -1;
+inline int skyboxArea = AREA_INVALID;
 inline Matrix4 skyboxTransform;