add CollisionInvSphere

panda/src/collide/Sources.pp

@@ -18,6 +18,7 @@
     collisionHandlerPhysical.I collisionHandlerPhysical.h  \
     collisionHandlerPusher.I collisionHandlerPusher.h  \
     collisionHandlerQueue.h \
+    collisionInvSphere.I collisionInvSphere.h \
     collisionLine.I collisionLine.h \
     collisionLevelState.I collisionLevelState.h \
     collisionNode.I collisionNode.h \
@@ -43,6 +44,7 @@
     collisionHandlerPusher.cxx \
     collisionHandlerQueue.cxx  \
     collisionLevelState.cxx \
+    collisionInvSphere.cxx  \
     collisionLine.cxx \
     collisionNode.cxx \
     collisionPlane.cxx  \
@@ -66,6 +68,7 @@
     collisionHandlerPhysical.I collisionHandlerPhysical.h \
     collisionHandlerPusher.I collisionHandlerPusher.h \
     collisionHandlerQueue.h \
+    collisionInvSphere.I collisionInvSphere.h \
     collisionLevelState.I collisionLevelState.h \
     collisionLine.I collisionLine.h \
     collisionNode.I collisionNode.h \

panda/src/collide/collide_composite1.cxx

@@ -7,7 +7,7 @@
 #include "collisionHandlerPhysical.cxx"
 #include "collisionHandlerPusher.cxx"
 #include "collisionHandlerQueue.cxx"
+#include "collisionInvSphere.cxx"
 #include "collisionLevelState.cxx"
 #include "collisionLine.cxx"
-#include "collisionNode.cxx"
 

panda/src/collide/collide_composite2.cxx

@@ -1,3 +1,4 @@
+#include "collisionNode.cxx"
 #include "collisionPlane.cxx"
 #include "collisionPolygon.cxx"
 #include "collisionRay.cxx"

panda/src/collide/collisionInvSphere.I

@@ -0,0 +1,61 @@
+// Filename: collisionInvSphere.I
+// Created by:  drose (05Jan05)
+//
+////////////////////////////////////////////////////////////////////
+//
+// PANDA 3D SOFTWARE
+// Copyright (c) 2001 - 2004, Disney Enterprises, Inc.  All rights reserved
+//
+// All use of this software is subject to the terms of the Panda 3d
+// Software license.  You should have received a copy of this license
+// along with this source code; you will also find a current copy of
+// the license at http://etc.cmu.edu/panda3d/docs/license/ .
+//
+// To contact the maintainers of this program write to
+// panda3d-general@lists.sourceforge.net .
+//
+////////////////////////////////////////////////////////////////////
+
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::Constructor
+//       Access: Public
+//  Description:
+////////////////////////////////////////////////////////////////////
+INLINE CollisionInvSphere::
+CollisionInvSphere(const LPoint3f &center, float radius) :
+  CollisionSphere(center, radius)
+{
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::Constructor
+//       Access: Public
+//  Description:
+////////////////////////////////////////////////////////////////////
+INLINE CollisionInvSphere::
+CollisionInvSphere(float cx, float cy, float cz, float radius) :
+  CollisionSphere(cx, cy, cz, radius)
+{
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::Default constructor
+//       Access: Protected
+//  Description: Creates an invalid sphere.  Only used when reading
+//               from a bam file.
+////////////////////////////////////////////////////////////////////
+INLINE CollisionInvSphere::
+CollisionInvSphere() {
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::Copy Constructor
+//       Access: Public
+//  Description:
+////////////////////////////////////////////////////////////////////
+INLINE CollisionInvSphere::
+CollisionInvSphere(const CollisionInvSphere &copy) :
+  CollisionSphere(copy)
+{
+}

panda/src/collide/collisionInvSphere.cxx

@@ -0,0 +1,385 @@
+// Filename: collisionInvSphere.cxx
+// Created by:  drose (05Jan05)
+//
+////////////////////////////////////////////////////////////////////
+//
+// PANDA 3D SOFTWARE
+// Copyright (c) 2001 - 2004, Disney Enterprises, Inc.  All rights reserved
+//
+// All use of this software is subject to the terms of the Panda 3d
+// Software license.  You should have received a copy of this license
+// along with this source code; you will also find a current copy of
+// the license at http://etc.cmu.edu/panda3d/docs/license/ .
+//
+// To contact the maintainers of this program write to
+// panda3d-general@lists.sourceforge.net .
+//
+////////////////////////////////////////////////////////////////////
+
+#include "collisionInvSphere.h"
+#include "collisionSphere.h"
+#include "collisionLine.h"
+#include "collisionRay.h"
+#include "collisionSegment.h"
+#include "collisionHandler.h"
+#include "collisionEntry.h"
+#include "config_collide.h"
+
+#include "omniBoundingVolume.h"
+#include "datagram.h"
+#include "datagramIterator.h"
+#include "bamReader.h"
+#include "bamWriter.h"
+#include "geomTristrip.h"
+#include "nearly_zero.h"
+
+TypeHandle CollisionInvSphere::_type_handle;
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::make_copy
+//       Access: Public, Virtual
+//  Description:
+////////////////////////////////////////////////////////////////////
+CollisionSolid *CollisionInvSphere::
+make_copy() {
+  return new CollisionInvSphere(*this);
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::test_intersection
+//       Access: Public, Virtual
+//  Description:
+////////////////////////////////////////////////////////////////////
+PT(CollisionEntry) CollisionInvSphere::
+test_intersection(const CollisionEntry &) const {
+  report_undefined_from_intersection(get_type());
+  return NULL;
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::output
+//       Access: Public, Virtual
+//  Description:
+////////////////////////////////////////////////////////////////////
+void CollisionInvSphere::
+output(ostream &out) const {
+  out << "invsphere, c (" << get_center() << "), r " << get_radius();
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::recompute_bound
+//       Access: Protected, Virtual
+//  Description:
+////////////////////////////////////////////////////////////////////
+BoundingVolume *CollisionInvSphere::
+recompute_bound() {
+  BoundedObject::recompute_bound();
+  // An inverse sphere always has an infinite bounding volume, since
+  // everything outside the sphere is solid matter.
+  return set_bound_ptr(new OmniBoundingVolume());
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::test_intersection_from_sphere
+//       Access: Public, Virtual
+//  Description:
+////////////////////////////////////////////////////////////////////
+PT(CollisionEntry) CollisionInvSphere::
+test_intersection_from_sphere(const CollisionEntry &entry) const {
+  const CollisionSphere *sphere;
+  DCAST_INTO_R(sphere, entry.get_from(), 0);
+
+  const LMatrix4f &wrt_mat = entry.get_wrt_mat();
+
+  LPoint3f from_center = sphere->get_center() * wrt_mat;
+  LVector3f from_radius_v =
+    LVector3f(sphere->get_radius(), 0.0f, 0.0f) * wrt_mat;
+  float from_radius = length(from_radius_v);
+
+  LPoint3f into_center = get_center();
+  float into_radius = get_radius();
+
+  LVector3f vec = from_center - into_center;
+  float dist2 = dot(vec, vec);
+  if (dist2 < (into_radius - from_radius) * (into_radius - from_radius)) {
+    // No intersection--the sphere is within the hollow.
+    return NULL;
+  }
+
+  if (collide_cat.is_debug()) {
+    collide_cat.debug()
+      << "intersection detected from " << entry.get_from_node_path()
+      << " into " << entry.get_into_node_path() << "\n";
+  }
+  PT(CollisionEntry) new_entry = new CollisionEntry(entry);
+
+  LVector3f surface_normal;
+  float vec_length = vec.length();
+  if (IS_NEARLY_ZERO(vec_length)) {
+    // If we don't have a collision normal (e.g. the centers are
+    // exactly coincident), then make up an arbitrary normal--any one
+    // is as good as any other.
+    surface_normal.set(1.0, 0.0, 0.0);
+  } else {
+    surface_normal = -vec / vec_length;
+  }
+
+  LVector3f normal = (has_effective_normal() && sphere->get_respect_effective_normal()) ? get_effective_normal() : surface_normal;
+
+  new_entry->set_surface_normal(normal);
+  new_entry->set_surface_point(into_center - surface_normal * into_radius);
+  new_entry->set_interior_point(from_center - surface_normal * from_radius);
+
+  return new_entry;
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::test_intersection_from_line
+//       Access: Public, Virtual
+//  Description:
+////////////////////////////////////////////////////////////////////
+PT(CollisionEntry) CollisionInvSphere::
+test_intersection_from_line(const CollisionEntry &entry) const {
+  const CollisionLine *line;
+  DCAST_INTO_R(line, entry.get_from(), 0);
+
+  const LMatrix4f &wrt_mat = entry.get_wrt_mat();
+
+  LPoint3f from_origin = line->get_origin() * wrt_mat;
+  LVector3f from_direction = line->get_direction() * wrt_mat;
+
+  double t1, t2;
+  if (!intersects_line(t1, t2, from_origin, from_direction)) {
+    // The line is in the middle of space, and therefore intersects
+    // the sphere.
+    t1 = t2 = 0.0;
+  }
+
+  if (collide_cat.is_debug()) {
+    collide_cat.debug()
+      << "intersection detected from " << entry.get_from_node_path()
+      << " into " << entry.get_into_node_path() << "\n";
+  }
+  PT(CollisionEntry) new_entry = new CollisionEntry(entry);
+
+  LPoint3f into_intersection_point = from_origin + t2 * from_direction;
+  new_entry->set_surface_point(into_intersection_point);
+
+  if (has_effective_normal() && line->get_respect_effective_normal()) {
+    new_entry->set_surface_normal(get_effective_normal());
+  } else {
+    LVector3f normal = into_intersection_point - get_center();
+    normal.normalize();
+    new_entry->set_surface_normal(-normal);
+  }
+
+  return new_entry;
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::test_intersection_from_ray
+//       Access: Public, Virtual
+//  Description:
+////////////////////////////////////////////////////////////////////
+PT(CollisionEntry) CollisionInvSphere::
+test_intersection_from_ray(const CollisionEntry &entry) const {
+  const CollisionRay *ray;
+  DCAST_INTO_R(ray, entry.get_from(), 0);
+
+  const LMatrix4f &wrt_mat = entry.get_wrt_mat();
+
+  LPoint3f from_origin = ray->get_origin() * wrt_mat;
+  LVector3f from_direction = ray->get_direction() * wrt_mat;
+
+  double t1, t2;
+  if (!intersects_line(t1, t2, from_origin, from_direction)) {
+    // The ray is in the middle of space, and therefore intersects
+    // the sphere.
+    t1 = t2 = 0.0;
+  }
+
+  t2 = max(t2, 0.0);
+
+  if (collide_cat.is_debug()) {
+    collide_cat.debug()
+      << "intersection detected from " << entry.get_from_node_path()
+      << " into " << entry.get_into_node_path() << "\n";
+  }
+  PT(CollisionEntry) new_entry = new CollisionEntry(entry);
+
+  LPoint3f into_intersection_point;
+  into_intersection_point = from_origin + t2 * from_direction;
+  new_entry->set_surface_point(into_intersection_point);
+
+  if (has_effective_normal() && ray->get_respect_effective_normal()) {
+    new_entry->set_surface_normal(get_effective_normal());
+  } else {
+    LVector3f normal = into_intersection_point - get_center();
+    normal.normalize();
+    new_entry->set_surface_normal(-normal);
+  }
+
+  return new_entry;
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::test_intersection_from_segment
+//       Access: Public, Virtual
+//  Description:
+////////////////////////////////////////////////////////////////////
+PT(CollisionEntry) CollisionInvSphere::
+test_intersection_from_segment(const CollisionEntry &entry) const {
+  const CollisionSegment *segment;
+  DCAST_INTO_R(segment, entry.get_from(), 0);
+
+  const LMatrix4f &wrt_mat = entry.get_wrt_mat();
+
+  LPoint3f from_a = segment->get_point_a() * wrt_mat;
+  LPoint3f from_b = segment->get_point_b() * wrt_mat;
+  LVector3f from_direction = from_b - from_a;
+
+  double t1, t2;
+  if (!intersects_line(t1, t2, from_a, from_direction)) {
+    // The segment is in the middle of space, and therefore intersects
+    // the sphere.
+    t1 = t2 = 0.0;
+  }
+  
+  double t;
+  if (t2 <= 0.0) {
+    // The segment is completely below the shell.
+    t = 0.0;
+
+  } else if (t1 >= 1.0) {
+    // The segment is completely above the shell.
+    t = 1.0;
+
+  } else if (t2 <= 1.0) {
+    // The bottom edge of the segment intersects the shell.
+    t = min(t2, 1.0);
+
+  } else if (t1 >= 0.0) {
+    // The top edge of the segment intersects the shell.
+    t = max(t1, 0.0);
+
+  } else {
+    // Neither edge of the segment intersects the shell.  It follows
+    // that both intersection points are within the hollow center of
+    // the sphere; therefore, there is no intersection.
+    return NULL;
+  }
+
+  if (collide_cat.is_debug()) {
+    collide_cat.debug()
+      << "intersection detected from " << entry.get_from_node_path()
+      << " into " << entry.get_into_node_path() << "\n";
+  }
+  PT(CollisionEntry) new_entry = new CollisionEntry(entry);
+
+  LPoint3f into_intersection_point = from_a + t * from_direction;
+  new_entry->set_surface_point(into_intersection_point);
+
+  if (has_effective_normal() && segment->get_respect_effective_normal()) {
+    new_entry->set_surface_normal(get_effective_normal());
+  } else {
+    LVector3f normal = into_intersection_point - get_center();
+    normal.normalize();
+    new_entry->set_surface_normal(-normal);
+  }
+
+  return new_entry;
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::fill_viz_geom
+//       Access: Protected, Virtual
+//  Description: Fills the _viz_geom GeomNode up with Geoms suitable
+//               for rendering this solid.
+////////////////////////////////////////////////////////////////////
+void CollisionInvSphere::
+fill_viz_geom() {
+  if (collide_cat.is_debug()) {
+    collide_cat.debug()
+      << "Recomputing viz for " << *this << "\n";
+  }
+
+  static const int num_slices = 8;
+  static const int num_stacks = 8;
+
+  GeomTristrip *sphere = new GeomTristrip;
+  PTA_Vertexf verts;
+  PTA_int lengths;
+  verts.reserve((num_stacks * 2) * num_slices);
+  lengths.reserve(num_slices);
+
+  for (int sl = 0; sl < num_slices; sl++) {
+    float longitude0 = (float)sl / (float)num_slices;
+    float longitude1 = (float)(sl + 1) / (float)num_slices;
+    verts.push_back(compute_point(0.0, longitude0));
+    for (int st = 1; st < num_stacks; st++) {
+      float latitude = (float)st / (float)num_stacks;
+      verts.push_back(compute_point(latitude, longitude1));
+      verts.push_back(compute_point(latitude, longitude0));
+    }
+    verts.push_back(compute_point(1.0, longitude0));
+
+    lengths.push_back(num_stacks * 2);
+  }
+
+  sphere->set_coords(verts);
+  sphere->set_lengths(lengths);
+  sphere->set_num_prims(num_slices);
+
+  _viz_geom->add_geom(sphere, get_solid_viz_state());
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::register_with_read_factory
+//       Access: Public, Static
+//  Description: Factory method to generate a CollisionInvSphere object
+////////////////////////////////////////////////////////////////////
+void CollisionInvSphere::
+register_with_read_factory() {
+  BamReader::get_factory()->register_factory(get_class_type(), make_CollisionInvSphere);
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::write_datagram
+//       Access: Public
+//  Description: Function to write the important information in
+//               the particular object to a Datagram
+////////////////////////////////////////////////////////////////////
+void CollisionInvSphere::
+write_datagram(BamWriter *manager, Datagram &me) {
+  CollisionSphere::write_datagram(manager, me);
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::make_CollisionInvSphere
+//       Access: Protected
+//  Description: Factory method to generate a CollisionInvSphere object
+////////////////////////////////////////////////////////////////////
+TypedWritable *CollisionInvSphere::
+make_CollisionInvSphere(const FactoryParams &params) {
+  CollisionInvSphere *me = new CollisionInvSphere;
+  DatagramIterator scan;
+  BamReader *manager;
+
+  parse_params(params, scan, manager);
+  me->fillin(scan, manager);
+  return me;
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionInvSphere::fillin
+//       Access: Protected
+//  Description: Function that reads out of the datagram (or asks
+//               manager to read) all of the data that is needed to
+//               re-create this object and stores it in the appropiate
+//               place
+////////////////////////////////////////////////////////////////////
+void CollisionInvSphere::
+fillin(DatagramIterator& scan, BamReader* manager) {
+  CollisionSphere::fillin(scan, manager);
+}
+

panda/src/collide/collisionInvSphere.h

@@ -0,0 +1,96 @@
+// Filename: collisionInvSphere.h
+// Created by:  drose (05Jan05)
+//
+////////////////////////////////////////////////////////////////////
+//
+// PANDA 3D SOFTWARE
+// Copyright (c) 2001 - 2004, Disney Enterprises, Inc.  All rights reserved
+//
+// All use of this software is subject to the terms of the Panda 3d
+// Software license.  You should have received a copy of this license
+// along with this source code; you will also find a current copy of
+// the license at http://etc.cmu.edu/panda3d/docs/license/ .
+//
+// To contact the maintainers of this program write to
+// panda3d-general@lists.sourceforge.net .
+//
+////////////////////////////////////////////////////////////////////
+
+#ifndef COLLISIONINVSPHERE_H
+#define COLLISIONINVSPHERE_H
+
+#include "pandabase.h"
+
+#include "collisionSphere.h"
+
+///////////////////////////////////////////////////////////////////
+//       Class : CollisionInvSphere
+// Description : An inverted sphere: this is a sphere whose collision
+//               surface is the inside surface of the sphere.
+//               Everything outside the sphere is solid matter;
+//               everything inside is empty space.  Useful for
+//               constraining objects to remain within a spherical
+//               perimeter.
+////////////////////////////////////////////////////////////////////
+class EXPCL_PANDA CollisionInvSphere : public CollisionSphere {
+PUBLISHED:
+  INLINE CollisionInvSphere(const LPoint3f &center, float radius);
+  INLINE CollisionInvSphere(float cx, float cy, float cz, float radius);
+
+protected:
+  INLINE CollisionInvSphere();
+
+public:
+  INLINE CollisionInvSphere(const CollisionInvSphere &copy);
+  virtual CollisionSolid *make_copy();
+
+  virtual PT(CollisionEntry)
+  test_intersection(const CollisionEntry &entry) const;
+
+  virtual void output(ostream &out) const;
+
+protected:
+  virtual BoundingVolume *recompute_bound();
+
+  virtual PT(CollisionEntry)
+  test_intersection_from_sphere(const CollisionEntry &entry) const;
+  virtual PT(CollisionEntry)
+  test_intersection_from_line(const CollisionEntry &entry) const;
+  virtual PT(CollisionEntry)
+  test_intersection_from_ray(const CollisionEntry &entry) const;
+  virtual PT(CollisionEntry)
+  test_intersection_from_segment(const CollisionEntry &entry) const;
+
+  virtual void fill_viz_geom();
+
+public:
+  static void register_with_read_factory();
+  virtual void write_datagram(BamWriter *manager, Datagram &me);
+
+protected:
+  static TypedWritable *make_CollisionInvSphere(const FactoryParams &params);
+  void fillin(DatagramIterator &scan, BamReader *manager);
+
+public:
+  static TypeHandle get_class_type() {
+    return _type_handle;
+  }
+  static void init_type() {
+    CollisionSphere::init_type();
+    register_type(_type_handle, "CollisionInvSphere",
+                  CollisionSphere::get_class_type());
+  }
+  virtual TypeHandle get_type() const {
+    return get_class_type();
+  }
+  virtual TypeHandle force_init_type() {init_type(); return get_class_type();}
+
+private:
+  static TypeHandle _type_handle;
+};
+
+#include "collisionInvSphere.I"
+
+#endif
+
+

panda/src/collide/collisionSphere.I

@@ -41,7 +41,7 @@ CollisionSphere(float cx, float cy, float cz, float radius) :
 
 ////////////////////////////////////////////////////////////////////
 //     Function: CollisionSphere::Default constructor
-//       Access: Private
+//       Access: Protected
 //  Description: Creates an invalid sphere.  Only used when reading
 //               from a bam file.
 ////////////////////////////////////////////////////////////////////

panda/src/collide/collisionSphere.cxx

@@ -30,8 +30,10 @@
 #include "datagramIterator.h"
 #include "bamReader.h"
 #include "bamWriter.h"
-#include "geomSphere.h"
+#include "geomTristrip.h"
 #include "nearly_zero.h"
+#include "cmath.h"
+#include "mathNumbers.h"
 
 TypeHandle CollisionSphere::_type_handle;
 
@@ -92,7 +94,7 @@ get_collision_origin() const {
 ////////////////////////////////////////////////////////////////////
 void CollisionSphere::
 output(ostream &out) const {
-  out << "csphere, c (" << _center << "), r " << _radius;
+  out << "sphere, c (" << get_center() << "), r " << get_radius();
 }
 
 ////////////////////////////////////////////////////////////////////
@@ -128,8 +130,8 @@ test_intersection_from_sphere(const CollisionEntry &entry) const {
     LVector3f(sphere->get_radius(), 0.0f, 0.0f) * wrt_mat;
   float from_radius = length(from_radius_v);
 
-  LPoint3f into_center = _center;
-  float into_radius = _radius;
+  LPoint3f into_center = get_center();
+  float into_radius = get_radius();
 
   LVector3f vec = from_center - into_center;
   float dist2 = dot(vec, vec);
@@ -140,8 +142,8 @@ test_intersection_from_sphere(const CollisionEntry &entry) const {
 
   if (collide_cat.is_debug()) {
     collide_cat.debug()
-      << "intersection detected from " << entry.get_from_node_path() << " into "
-      << entry.get_into_node_path() << "\n";
+      << "intersection detected from " << entry.get_from_node_path()
+      << " into " << entry.get_into_node_path() << "\n";
   }
   PT(CollisionEntry) new_entry = new CollisionEntry(entry);
 
@@ -199,7 +201,7 @@ test_intersection_from_line(const CollisionEntry &entry) const {
   if (has_effective_normal() && line->get_respect_effective_normal()) {
     new_entry->set_surface_normal(get_effective_normal());
   } else {
-    LVector3f normal = into_intersection_point - _center;
+    LVector3f normal = into_intersection_point - get_center();
     normal.normalize();
     new_entry->set_surface_normal(normal);
   }
@@ -233,6 +235,8 @@ test_intersection_from_ray(const CollisionEntry &entry) const {
     return NULL;
   }
 
+  t1 = max(t1, 0.0);
+
   if (collide_cat.is_debug()) {
     collide_cat.debug()
       << "intersection detected from " << entry.get_from_node_path()
@@ -240,22 +244,13 @@ test_intersection_from_ray(const CollisionEntry &entry) const {
   }
   PT(CollisionEntry) new_entry = new CollisionEntry(entry);
 
-  LPoint3f into_intersection_point;
-  if (t1 < 0.0) {
-    // Point a is within the sphere.  The first intersection point is
-    // point a itself.
-    into_intersection_point = from_origin;
-  } else {
-    // Point a is outside the sphere.  The first intersection point is
-    // at t1.
-    into_intersection_point = from_origin + t1 * from_direction;
-  }
+  LPoint3f into_intersection_point = from_origin + t1 * from_direction;
   new_entry->set_surface_point(into_intersection_point);
 
   if (has_effective_normal() && ray->get_respect_effective_normal()) {
     new_entry->set_surface_normal(get_effective_normal());
   } else {
-    LVector3f normal = into_intersection_point - _center;
+    LVector3f normal = into_intersection_point - get_center();
     normal.normalize();
     new_entry->set_surface_normal(normal);
   }
@@ -291,6 +286,8 @@ test_intersection_from_segment(const CollisionEntry &entry) const {
     return NULL;
   }
 
+  t1 = max(t1, 0.0);
+
   if (collide_cat.is_debug()) {
     collide_cat.debug()
       << "intersection detected from " << entry.get_from_node_path()
@@ -298,22 +295,13 @@ test_intersection_from_segment(const CollisionEntry &entry) const {
   }
   PT(CollisionEntry) new_entry = new CollisionEntry(entry);
 
-  LPoint3f into_intersection_point;
-  if (t1 < 0.0) {
-    // Point a is within the sphere.  The first intersection point is
-    // point a itself.
-    into_intersection_point = from_a;
-  } else {
-    // Point a is outside the sphere, and point b is either inside the
-    // sphere or beyond it.  The first intersection point is at t1.
-    into_intersection_point = from_a + t1 * from_direction;
-  }
+  LPoint3f into_intersection_point = from_a + t1 * from_direction;
   new_entry->set_surface_point(into_intersection_point);
 
   if (has_effective_normal() && segment->get_respect_effective_normal()) {
     new_entry->set_surface_normal(get_effective_normal());
   } else {
-    LVector3f normal = into_intersection_point - _center;
+    LVector3f normal = into_intersection_point - get_center();
     normal.normalize();
     new_entry->set_surface_normal(normal);
   }
@@ -334,19 +322,39 @@ fill_viz_geom() {
       << "Recomputing viz for " << *this << "\n";
   }
 
-  GeomSphere *sphere = new GeomSphere;
+  static const int num_slices = 8;
+  static const int num_stacks = 8;
+
+  GeomTristrip *sphere = new GeomTristrip;
   PTA_Vertexf verts;
-  verts.push_back(_center);
-  verts.push_back(_center + LVector3f(_radius, 0.0f, 0.0f));
+  PTA_int lengths;
+  verts.reserve((num_stacks * 2) * num_slices);
+  lengths.reserve(num_slices);
+
+  for (int sl = 0; sl < num_slices; sl++) {
+    float longitude0 = (float)sl / (float)num_slices;
+    float longitude1 = (float)(sl + 1) / (float)num_slices;
+    verts.push_back(compute_point(0.0, longitude0));
+    for (int st = 1; st < num_stacks; st++) {
+      float latitude = (float)st / (float)num_stacks;
+      verts.push_back(compute_point(latitude, longitude0));
+      verts.push_back(compute_point(latitude, longitude1));
+    }
+    verts.push_back(compute_point(1.0, longitude0));
+
+    lengths.push_back(num_stacks * 2);
+  }
+
   sphere->set_coords(verts);
-  sphere->set_num_prims(1);
+  sphere->set_lengths(lengths);
+  sphere->set_num_prims(num_slices);
 
   _viz_geom->add_geom(sphere, get_solid_viz_state());
 }
 
 ////////////////////////////////////////////////////////////////////
 //     Function: CollisionSphere::intersects_line
-//       Access: Private
+//       Access: Protected
 //  Description: Determine the point(s) of intersection of a parametric
 //               line with the sphere.  The line is infinite in both
 //               directions, and passes through "from" and from+delta.
@@ -394,10 +402,10 @@ intersects_line(double &t1, double &t2,
 
   nassertr(A != 0.0, false);
 
-  LVector3f fc = from - _center;
+  LVector3f fc = from - get_center();
   double B = 2.0f* dot(delta, fc);
   double fc_d2 = dot(fc, fc);
-  double C = fc_d2 - _radius * _radius;
+  double C = fc_d2 - get_radius() * get_radius();
 
   double radical = B*B - 4.0*A*C;
 
@@ -419,6 +427,26 @@ intersects_line(double &t1, double &t2,
   return true;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: CollisionSphere::compute_point
+//       Access: Protected
+//  Description: Returns a point on the surface of the sphere.
+//               latitude and longitude range from 0.0 to 1.0.  This
+//               is used by fill_viz_geom() to create a visible
+//               representation of the sphere.
+////////////////////////////////////////////////////////////////////
+Vertexf CollisionSphere::
+compute_point(float latitude, float longitude) const {
+  float s1, c1;
+  csincos(latitude * MathNumbers::pi_f, &s1, &c1);
+
+  float s2, c2;
+  csincos(longitude * 2.0f * MathNumbers::pi_f, &s2, &c2);
+
+  Vertexf p(s1 * c2, s1 * s2, c1);
+  return p * get_radius() + get_center();
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: CollisionSphere::register_with_read_factory
 //       Access: Public, Static

panda/src/collide/collisionSphere.h

@@ -32,7 +32,7 @@ PUBLISHED:
   INLINE CollisionSphere(const LPoint3f &center, float radius);
   INLINE CollisionSphere(float cx, float cy, float cz, float radius);
 
-private:
+protected:
   INLINE CollisionSphere();
 
 public:
@@ -69,9 +69,10 @@ protected:
 
   virtual void fill_viz_geom();
 
-private:
+protected:
   bool intersects_line(double &t1, double &t2,
                        const LPoint3f &from, const LVector3f &delta) const;
+  Vertexf compute_point(float latitude, float longitude) const;
 
 private:
   LPoint3f _center;

panda/src/collide/config_collide.cxx

@@ -25,6 +25,7 @@
 #include "collisionHandlerPhysical.h"
 #include "collisionHandlerPusher.h"
 #include "collisionHandlerQueue.h"
+#include "collisionInvSphere.h"
 #include "collisionLine.h"
 #include "collisionNode.h"
 #include "collisionPlane.h"
@@ -86,6 +87,7 @@ init_libcollide() {
   CollisionHandlerPhysical::init_type();
   CollisionHandlerPusher::init_type();
   CollisionHandlerQueue::init_type();
+  CollisionInvSphere::init_type();
   CollisionLine::init_type();
   CollisionNode::init_type();
   CollisionPlane::init_type();
@@ -101,8 +103,7 @@ init_libcollide() {
   CollisionVisualizer::init_type();
 #endif
 
-  // Registration of writeable object's creation
-  // functions with BamReader's factory
+  CollisionInvSphere::register_with_read_factory();
   CollisionLine::register_with_read_factory();
   CollisionNode::register_with_read_factory();
   CollisionPlane::register_with_read_factory();