Added a front frustum plane which isn't really used for anything yet, but it could be interesting for testing different depth culling approaches.

frustum.c

@@ -4,7 +4,7 @@
 
 #include <inline_c.h>
 
-static SVECTOR *left, *right, *top, *bottom;
+static SVECTOR *left, *right, *top, *bottom, *front;
 
 static INLINE void frustum_buildPlane(MATRIX *rot_matrix, VECTOR *normal, SVECTOR *outPlane)
 {
@@ -15,7 +15,7 @@ static INLINE void frustum_buildPlane(MATRIX *rot_matrix, VECTOR *normal, SVECTO
 
 void frustum_update(int width, int height)
 {
-    VECTOR l, r, t, b;
+    VECTOR l, r, t, b, f;
 
     int near;
     gte_ReadGeomScreen(&near);
@@ -41,6 +41,10 @@ void frustum_update(int width, int height)
     t.vy = ONE;
     t.vz = -b.vz;
 
+    f.vx = 0;
+    f.vy = ONE;
+    f.vz = 0;
+
     MATRIX rot_matrix;
     RotMatrixQ(&cam_rot, &rot_matrix);
 
@@ -49,11 +53,14 @@ void frustum_update(int width, int height)
     right =     (SVECTOR*)(scratchpad + sizeof(SVECTOR) * 1);
     top =       (SVECTOR*)(scratchpad + sizeof(SVECTOR) * 2);
     bottom =    (SVECTOR*)(scratchpad + sizeof(SVECTOR) * 3);
+    front =     (SVECTOR*)(scratchpad + sizeof(SVECTOR) * 4);
 
     frustum_buildPlane(&rot_matrix, &l, left);
     frustum_buildPlane(&rot_matrix, &r, right);
     frustum_buildPlane(&rot_matrix, &t, top);
     frustum_buildPlane(&rot_matrix, &b, bottom);
+    frustum_buildPlane(&rot_matrix, &f, front);
+    front->pad -= near >> 1;
 
     // FntPrint(-1, "l = %d %d, r = %d %d, t = %d %d, b = %d %d\n", 
     //     left.vx, left.pad, right.vx, right.pad, top.vz, top.pad, bottom.vz, bottom.pad);
@@ -99,3 +106,8 @@ u_char frustum_boxInside(const SVECTOR *min, const SVECTOR *max)
     if (frustum_pointInside_((SVECTOR) { max->vx, max->vy, max->vz })) return 1;
     return 0;
 }
+
+int frustum_pointDepth(const SVECTOR *point)
+{
+    return m_dot12(front, point) + front->pad;
+}

frustum.h

@@ -5,5 +5,6 @@ void frustum_update(int width, int height);
 u_char frustum_pointInside(const SVECTOR *point);
 u_char frustum_sphereInside(const SVECTOR *sphere);
 u_char frustum_boxInside(const SVECTOR *min, const SVECTOR *max);
+int frustum_pointDepth(const SVECTOR *point);
 
 #endif  // __FRUSTUM_H__

world.c

@@ -469,7 +469,7 @@ void world_draw(const world_t *world)
 
     cam_leaf = world_leafAtPoint(world, &cam_pos);
 
-    u_char *pvsbuf = scratchpad + 32;   // Place the PVS data after the frustum in fast RAM
+    u_char *pvsbuf = scratchpad + 48;   // Place the PVS data after the frustum in fast RAM
     u_char *pvs = world_loadVisData(world, cam_leaf, &pvsbuf);
     //u_char *pvs = world_noVisData(world, &pvsbuf);