From f4cfe4c207c5219d98d3c31311ae13fdb0e245ff Mon Sep 17 00:00:00 2001
From: david <david>
Date: Thu, 18 Jul 2002 13:23:29 +0000
Subject: [PATCH] Significant speedup for randomly-placed objects, by taking
 better advantage of ssg Frustum culling.

---
 src/Objects/newmat.cxx |  6 -----
 src/Objects/newmat.hxx |  9 --------
 src/Objects/obj.cxx    | 51 +++++++++++++++++++++++++++++++++---------
 3 files changed, 40 insertions(+), 26 deletions(-)

diff --git a/src/Objects/newmat.cxx b/src/Objects/newmat.cxx
index 0bcb9f887..67d4fba2a 100644
--- a/src/Objects/newmat.cxx
+++ b/src/Objects/newmat.cxx
@@ -181,21 +181,15 @@ FGNewMat::read_properties (const SGPropertyNode * props)
       ssgTexturePath((char *)path.dir().c_str());
       ssgEntity * model = load_object((char *)path.c_str());
       if (model != 0) {
-          // float ranges[] = {0, object_node->getDoubleValue("range-m", 2000)};
-          // object.model = new ssgRangeSelector;
-          // ((ssgRangeSelector *)object.model)->setRanges(ranges, 2);
 	if (object_node->getBoolValue("billboard", false)) {
 	  ssgCutout * cutout = new ssgCutout(false);
 	  cutout->addKid(model);
-	  // ((ssgBranch *)object.model)->addKid(cutout);
 	  object.model = cutout;
 	} else {
-            // ((ssgBranch *)object.model)->addKid(model);
             object.model = model;
 	}
 	object.model->ref();
 	object.coverage = object_node->getDoubleValue("coverage", 100000);
-	object.group_lod = object_node->getDoubleValue("group-range-m", 5000);
 	object.lod = object_node->getDoubleValue("range-m", 2000);
 	objects.push_back(object);
       } else {
diff --git a/src/Objects/newmat.hxx b/src/Objects/newmat.hxx
index fedfda1d4..3e9f05a66 100644
--- a/src/Objects/newmat.hxx
+++ b/src/Objects/newmat.hxx
@@ -167,14 +167,6 @@ public:
   }
 
 
-  /**
-   * Get the group LOD range for a dynamic object for this material.
-   */
-  virtual double get_object_group_lod (int i) const {
-    return objects[i].group_lod;
-  }
-
-
   /**
    * Get the target LOD range for a dynamic object for this material.
    */
@@ -261,7 +253,6 @@ private:
   {
     ssgEntity * model;
     double coverage;
-    double group_lod;
     double lod;
   };
 
diff --git a/src/Objects/obj.cxx b/src/Objects/obj.cxx
index de92cf219..d3c76f913 100644
--- a/src/Objects/obj.cxx
+++ b/src/Objects/obj.cxx
@@ -456,19 +456,49 @@ out_of_range_callback (ssgEntity * entity, int mask)
 
 
 /**
- * ssgEntity pre-traversal callback to skip a culling test.
+ * Singleton ssgEntity with a dummy bounding sphere, to fool culling.
  *
- * This is necessary so that the in-range/out-of-range callbacks will
- * be reached even when there is no leaf data underneath.
+ * This forces the in-range and out-of-range branches to be visited
+ * when appropriate, even if they have no children.  It's ugly, but
+ * it works and seems fairly efficient (since branches can still
+ * be culled when they're out of the view frustum).
+ */
+class DummyBSphereEntity : public ssgEntity
+{
+public:
+  virtual ~DummyBSphereEntity () {}
+  virtual void recalcBSphere () { bsphere_is_invalid = false; }
+  virtual void cull (sgFrustum *f, sgMat4 m, int test_needed) {}
+  virtual void isect (sgSphere *s, sgMat4 m, int test_needed) {}
+  virtual void hot (sgVec3 s, sgMat4 m, int test_needed) {}
+  virtual void los (sgVec3 s, sgMat4 m, int test_needed) {}
+  static ssgEntity * get_entity ();
+private:
+  DummyBSphereEntity ()
+  {
+    bsphere.setCenter(0, 0, 0);
+    bsphere.setRadius(10);
+  }
+  static DummyBSphereEntity * entity;
+};
+
+
+DummyBSphereEntity * DummyBSphereEntity::entity = 0;
+
+
+/**
+ * Ensure that only one copy of the dummy entity exists.
  *
- * @param entity The entity originating the callback (not used).
- * @param mask The entity's traversal mask (not used).
- * @return Always 2 to allow traversal without a cull test.
+ * @return The singleton copy of the DummyBSphereEntity.
  */
-static int
-notest_callback (ssgEntity * entity, int mask)
+ssgEntity *
+DummyBSphereEntity::get_entity ()
 {
-  return 2;
+  if (entity == 0) {
+    entity = new DummyBSphereEntity;
+    entity->ref();
+  }
+  return entity;
 }
 
 
@@ -503,7 +533,6 @@ setup_triangle (float * p1, float * p2, float * p3,
     sgMat4 TRANS;
     sgMakeTransMat4(TRANS, center);
     location->setTransform(TRANS);
-    location->setTravCallback(SSG_CALLBACK_PRETRAV, notest_callback);
     branch->addKid(location);
 
 				// Calculate the triangle area.
@@ -519,7 +548,6 @@ setup_triangle (float * p1, float * p2, float * p3,
 	float ranges[] = {0, mat->get_object_lod(i), 9999999};
 	ssgRangeSelector * lod = new ssgRangeSelector;
 	lod->setRanges(ranges, 3);
-	lod->setTravCallback(SSG_CALLBACK_PRETRAV, notest_callback);
 	location->addKid(lod);
 
 				// Create the in-range and out-of-range
@@ -550,6 +578,7 @@ setup_triangle (float * p1, float * p2, float * p3,
 	out_of_range->setUserData(data);
 	out_of_range->setTravCallback(SSG_CALLBACK_PRETRAV,
 				      out_of_range_callback);
+	out_of_range->addKid(DummyBSphereEntity::get_entity());
 	lod->addKid(out_of_range);
     }
 }
-- 
2.39.5