Keep track of the leaf a model is in, so that it doesn't need to be looked up every frame but instead only when the model moves.

ps1bsp.h

@@ -168,6 +168,7 @@ typedef struct ps1bsp_model_s
 
 	// Run-time data
 	const struct ps1bsp_model_s* nextModel;
+	const struct ps1bsp_leaf_s* currentLeaf;
 } ps1bsp_model_t;
 
 // Pre-parsed and encoded entity data (this runs the risk of becoming too bloated)

world.c

@@ -264,21 +264,26 @@ static void world_sortModels(const world_t *world)
     for (u_short modelIdx = 1; modelIdx < world->numModels; ++modelIdx)
     {
         ps1bsp_model_t* model = (ps1bsp_model_t*)&world->models[modelIdx];
-        
-        // TODO: refence leaf in model, update only when model moves
-
-        VECTOR pos;
-        pos.vx = model->origin.vx + model->boundingSphere.vx;
-        pos.vy = model->origin.vy + model->boundingSphere.vy;
-        pos.vz = model->origin.vz + model->boundingSphere.vz;
+        ps1bsp_leaf_t* leaf = (ps1bsp_leaf_t*)model->currentLeaf;
 
-        short leafIdx = world_leafAtPoint(world, &pos);
-        if (leafIdx >= 0)
+        // Update the model's current leaf. This only needs to be done when the model moves.
+        if (leaf == NULL)
         {
-            ps1bsp_leaf_t *leaf = (ps1bsp_leaf_t*)&world->leaves[leafIdx];
-            model->nextModel = leaf->models;
-            leaf->models = model;
+            VECTOR pos;
+            pos.vx = model->origin.vx + model->boundingSphere.vx;
+            pos.vy = model->origin.vy + model->boundingSphere.vy;
+            pos.vz = model->origin.vz + model->boundingSphere.vz;
+
+            short leafIdx = world_leafAtPoint(world, &pos);
+            if (leafIdx <= 0)
+                continue;
+                
+            leaf = (ps1bsp_leaf_t*)&world->leaves[leafIdx];
+            model->currentLeaf = leaf;
         }
+
+        model->nextModel = leaf->models;
+        leaf->models = model;
     }
 }