Small optimization to BSP tree traversal, by making the child node selection branchless

ps1bsp.h

@@ -92,8 +92,7 @@ typedef struct
 typedef struct
 {
 	int planeId;
-	short front;
-	short back;
+	short children[2];
 
 	// TODO: add bounding box for frustum culling
 	

world.c

@@ -287,16 +287,9 @@ static void world_drawnode(const world_t *world, short nodeIdx, u_char *pvs)
     short dist = world_pointPlaneDist(&cam_pos, plane);
     
     // Draw child nodes in front-to-back order; adding faces to the OT will reverse the drawing order
-    if (dist > 0)
-    {
-        world_drawnode(world, node->front, pvs);
-        world_drawnode(world, node->back, pvs);
-    }
-    else
-    {
-        world_drawnode(world, node->back, pvs);
-        world_drawnode(world, node->front, pvs);
-    }
+    char order = dist < 0;
+    world_drawnode(world, node->children[order], pvs);
+    world_drawnode(world, node->children[order ^ 1], pvs);
 }
 
 // Decompress PVS data for the given leaf ID and store it in RAM at the given buffer pointer location.
@@ -354,7 +347,7 @@ static u_short world_leafAtPoint(const world_t *world, const VECTOR *point)
         const ps1bsp_plane_t *plane = &world->planes[node->planeId];
 
         short dist = world_pointPlaneDist(point, plane);
-        nodeIdx = dist > 0 ? node->front : node->back;  // TODO: this can be done branchless with (dist < 0)^1
+        nodeIdx = node->children[(dist > 0) ^ 1];
     }
 
     return ~nodeIdx;