diff --git a/frustum.c b/frustum.c
index 26b2e25..f50865f 100644
--- a/frustum.c
+++ b/frustum.c
@@ -20,9 +20,9 @@ void frustum_update(int width, int height)
     int near;
     gte_ReadGeomScreen(&near);
     
-    //FntPrint(-1, "N = %d, W = %d, H = %d\n", near, width, height);
+    // FntPrint(-1, "N = %d, W = %d, H = %d\n", near, width, height);
 
-    // 2 * near, shifted left for division
+    // 2 * ONE * near
     near <<= 13;
 
     l.vx = near / width;
@@ -53,7 +53,7 @@ void frustum_update(int width, int height)
     //     left.vx, left.pad, right.vx, right.pad, top.vz, top.pad, bottom.vz, bottom.pad);
 }
 
-u_char frustum_pointInside(SVECTOR *point)
+u_char frustum_pointInside(const SVECTOR *point)
 {
     if (m_dot12(left, *point) + left.pad < 0) return 0;
     if (m_dot12(right, *point) + right.pad < 0) return 0;
@@ -62,7 +62,7 @@ u_char frustum_pointInside(SVECTOR *point)
     return 1;
 }
 
-u_char frustum_sphereInside(SVECTOR *sphere)
+u_char frustum_sphereInside(const SVECTOR *sphere)
 {
     short radius = -sphere->pad;
     if (m_dot12(left, *sphere) + left.pad < radius) return 0;
diff --git a/frustum.h b/frustum.h
index adcd50c..244502d 100644
--- a/frustum.h
+++ b/frustum.h
@@ -2,7 +2,7 @@
 #define __FRUSTUM_H__
 
 void frustum_update(int width, int height);
-u_char frustum_pointInside(SVECTOR *point);
-u_char frustum_sphereInside(SVECTOR *sphere);
+u_char frustum_pointInside(const SVECTOR *point);
+u_char frustum_sphereInside(const SVECTOR *sphere);
 
 #endif  // __FRUSTUM_H__
diff --git a/ps1bsp.h b/ps1bsp.h
index 9570fda..7b79a99 100755
--- a/ps1bsp.h
+++ b/ps1bsp.h
@@ -119,8 +119,8 @@ typedef struct
 	// Used for backface culling
 	SVECTOR center;
 
-	// Which frame was this face last drawn on? Used to check if this face should be drawn.
-	u_long drawFrame;
+	// Run-time data
+	u_long drawFrame;	// Which frame was this face last drawn on? Used to check if this face should be drawn.
 } ps1bsp_face_t;
 
 typedef struct
@@ -136,9 +136,7 @@ typedef struct
 	short children[2];
 
 	// TODO: add bounding box for frustum culling (or bounding sphere, might be cheaper)
-	
-	u_short firstFace;
-	u_short numFaces;
+	SVECTOR boundingSphere;
 } ps1bsp_node_t;
 
 typedef struct
@@ -151,6 +149,10 @@ typedef struct
 
 	u_short firstLeafFace;
 	u_short numLeafFaces;
+
+	// Run-time data
+	u_short nextLeaf;	// For chaining leafs in drawing order
+	u_short leafDepth;	// At what depth the leaf's faces should be placed in the ordering table
 } ps1bsp_leaf_t;
 
 // Pre-parsed and encoded entity data (this runs the risk of becoming too bloated)
diff --git a/test.ps1bsp b/test.ps1bsp
index 0ff67a1..a78b035 100755
Binary files a/test.ps1bsp and b/test.ps1bsp differ
diff --git a/world.c b/world.c
index c2d4518..ab179ca 100644
--- a/world.c
+++ b/world.c
@@ -3,6 +3,7 @@
 #include "display.h"
 #include "time.h"
 #include "draw.h"
+#include "frustum.h"
 
 static CVECTOR colors[] = 
 {
@@ -212,7 +213,11 @@ static void world_drawnode(const world_t *world, short nodeIdx, u_char *pvs)
         return;
     }
 
+    // Perform frustum culling
     const ps1bsp_node_t *node = &world->nodes[nodeIdx];
+    if (!frustum_sphereInside(&node->boundingSphere))
+        return;
+
     const ps1bsp_plane_t *plane = &world->planes[node->planeId];
     short dist = world_pointPlaneDist(&cam_pos, plane);