collisionNode.cxx

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/**
 * PANDA 3D SOFTWARE
 * Copyright (c) Carnegie Mellon University.  All rights reserved.
 *
 * All use of this software is subject to the terms of the revised BSD
 * license.  You should have received a copy of this license along
 * with this source code in a file named "LICENSE."
 *
 * @file collisionNode.cxx
 * @author drose
 * @date 2002-03-16
 */

#include "collisionNode.h"
#include "config_collide.h"

#include "geomNode.h"
#include "cullTraverserData.h"
#include "cullTraverser.h"
#include "renderState.h"
#include "transformState.h"
#include "colorScaleAttrib.h"
#include "transparencyAttrib.h"
#include "datagram.h"
#include "datagramIterator.h"
#include "bamReader.h"
#include "bamWriter.h"
#include "clockObject.h"
#include "boundingSphere.h"
#include "boundingBox.h"
#include "config_mathutil.h"

TypeHandle CollisionNode::_type_handle;


/**
 *
 */
CollisionNode::
CollisionNode(const std::string &name) :
  PandaNode(name),
  _from_collide_mask(get_default_collide_mask()),
  _collider_sort(0)
{
  set_cull_callback();

  // CollisionNodes are hidden by default.
  set_overall_hidden(true);

  // CollisionNodes have a certain set of bits on by default.
  set_into_collide_mask(get_default_collide_mask());
}

/**
 *
 */
CollisionNode::
CollisionNode(const CollisionNode &copy) :
  PandaNode(copy),
  _from_collide_mask(copy._from_collide_mask),
  _solids(copy._solids)
{
}

/**
 *
 */
CollisionNode::
~CollisionNode() {
}

/**
 * Returns a newly-allocated Node that is a shallow copy of this one.  It will
 * be a different Node pointer, but its internal data may or may not be shared
 * with that of the original Node.
 */
PandaNode *CollisionNode::
make_copy() const {
  return new CollisionNode(*this);
}

/**
 * Returns true if the node's name has extrinsic meaning and must be preserved
 * across a flatten operation, false otherwise.
 */
bool CollisionNode::
preserve_name() const {
  return true;
}

/**
 * Transforms the contents of this node by the indicated matrix, if it means
 * anything to do so.  For most kinds of nodes, this does nothing.
 */
void CollisionNode::
xform(const LMatrix4 &mat) {
  nassertv(!mat.is_nan());

  if (mat.almost_equal(LMatrix4::ident_mat())) {
    return;
  }

  Solids::iterator si;
  for (si = _solids.begin(); si != _solids.end(); ++si) {
    PT(CollisionSolid) solid = (*si).get_write_pointer();
    solid->xform(mat);
  }
  mark_internal_bounds_stale();
}

/**
 * Collapses this node with the other node, if possible, and returns a pointer
 * to the combined node, or NULL if the two nodes cannot safely be combined.
 *
 * The return value may be this, other, or a new node altogether.
 *
 * This function is called from GraphReducer::flatten(), and need not deal
 * with children; its job is just to decide whether to collapse the two nodes
 * and what the collapsed node should look like.
 */
PandaNode *CollisionNode::
combine_with(PandaNode *other) {
  if (flatten_collision_nodes) {
    if (is_exact_type(get_class_type()) &&
        other->is_exact_type(get_class_type())) {
      // Two CollisionNodes can combine, but only if they have the same name,
      // because the name is often meaningful, and only if they have the same
      // collide masks.
      CollisionNode *cother = DCAST(CollisionNode, other);
      if (get_name() == cother->get_name() &&
          get_from_collide_mask() == cother->get_from_collide_mask() &&
          get_into_collide_mask() == cother->get_into_collide_mask()) {
        const COWPT(CollisionSolid) *solids_begin = &cother->_solids[0];
        const COWPT(CollisionSolid) *solids_end = solids_begin + cother->_solids.size();
        _solids.insert(_solids.end(), solids_begin, solids_end);
        mark_internal_bounds_stale();
        return this;
      }

      // Two CollisionNodes with different names or different collide masks
      // can't combine.
    }
  }

  return nullptr;
}

/**
 * Returns the subset of CollideMask bits that may be set for this particular
 * type of PandaNode.  For most nodes, this is 0; it doesn't make sense to set
 * a CollideMask for most kinds of nodes.
 *
 * For nodes that can be collided with, such as GeomNode and CollisionNode,
 * this returns all bits on.
 */
CollideMask CollisionNode::
get_legal_collide_mask() const {
  return CollideMask::all_on();
}

/**
 * This function will be called during the cull traversal to perform any
 * additional operations that should be performed at cull time.  This may
 * include additional manipulation of render state or additional
 * visible/invisible decisions, or any other arbitrary operation.
 *
 * Note that this function will *not* be called unless set_cull_callback() is
 * called in the constructor of the derived class.  It is necessary to call
 * set_cull_callback() to indicated that we require cull_callback() to be
 * called.
 *
 * By the time this function is called, the node has already passed the
 * bounding-volume test for the viewing frustum, and the node's transform and
 * state have already been applied to the indicated CullTraverserData object.
 *
 * The return value is true if this node should be visible, or false if it
 * should be culled.
 */
bool CollisionNode::
cull_callback(CullTraverser *trav, CullTraverserData &data) {
  // Append our collision vizzes to the drawing, even though they're not
  // actually part of the scene graph.
  Solids::const_iterator si;
  for (si = _solids.begin(); si != _solids.end(); ++si) {
    CPT(CollisionSolid) solid = (*si).get_read_pointer();
    PT(PandaNode) node = solid->get_viz(trav, data, false);
    if (node != nullptr) {
      CullTraverserData next_data(data, node);

      // We don't want to inherit the render state from above for these guys.
      next_data._state = RenderState::make_empty();
      trav->traverse(next_data);
    }
  }

  if (respect_prev_transform) {
    // Determine the previous frame's position, relative to the current
    // position.
    NodePath node_path = data.get_node_path();
    CPT(TransformState) transform = node_path.get_net_transform()->invert_compose(node_path.get_net_prev_transform());

    if (!transform->is_identity()) {
      // If we have a velocity, also draw the previous frame's position,
      // ghosted.

      for (si = _solids.begin(); si != _solids.end(); ++si) {
        CPT(CollisionSolid) solid = (*si).get_read_pointer();
        PT(PandaNode) node = solid->get_viz(trav, data, false);
        if (node != nullptr) {
          CullTraverserData next_data(data, node);

          next_data._net_transform =
            next_data._net_transform->compose(transform);
          next_data._state = get_last_pos_state();
          trav->traverse(next_data);
        }
      }
    }
  }

  // Now carry on to render our child nodes.
  return true;
}

/**
 * Returns true if there is some value to visiting this particular node during
 * the cull traversal for any camera, false otherwise.  This will be used to
 * optimize the result of get_net_draw_show_mask(), so that any subtrees that
 * contain only nodes for which is_renderable() is false need not be visited.
 */
bool CollisionNode::
is_renderable() const {
  return true;
}

/**
 * A simple downcast check.  Returns true if this kind of node happens to
 * inherit from CollisionNode, false otherwise.
 *
 * This is provided as a a faster alternative to calling
 * is_of_type(CollisionNode::get_class_type()).
 */
bool CollisionNode::
is_collision_node() const {
  return true;
}


/**
 * Writes a brief description of the node to the indicated output stream.
 * This is invoked by the << operator.  It may be overridden in derived
 * classes to include some information relevant to the class.
 */
void CollisionNode::
output(std::ostream &out) const {
  PandaNode::output(out);
  out << " (" << _solids.size() << " solids)";
}

/**
 * Sets the "from" CollideMask.  In order for a collision to be detected from
 * this object into another object, the intersection of this object's "from"
 * mask and the other object's "into" mask must be nonzero.
 */
void CollisionNode::
set_from_collide_mask(CollideMask mask) {
  _from_collide_mask = mask;
}

/**
 * Called when needed to recompute the node's _internal_bound object.  Nodes
 * that contain anything of substance should redefine this to do the right
 * thing.
 */
void CollisionNode::
compute_internal_bounds(CPT(BoundingVolume) &internal_bounds,
                        int &internal_vertices,
                        int pipeline_stage,
                        Thread *current_thread) const {
  pvector<CPT(BoundingVolume) > child_volumes_ref;
  pvector<const BoundingVolume *> child_volumes;
  bool all_box = true;

  Solids::const_iterator gi;
  for (gi = _solids.begin(); gi != _solids.end(); ++gi) {
    CPT(CollisionSolid) solid = (*gi).get_read_pointer();
    CPT(BoundingVolume) volume = solid->get_bounds();

    if (!volume->is_empty()) {
      child_volumes_ref.push_back(volume);
      child_volumes.push_back(volume);
      if (!volume->is_exact_type(BoundingBox::get_class_type())) {
        all_box = false;
      }
    }
  }

  PT(GeometricBoundingVolume) gbv = new BoundingBox;

  BoundingVolume::BoundsType btype = get_bounds_type();
  if (btype == BoundingVolume::BT_default) {
    btype = bounds_type;
  }

  if (btype == BoundingVolume::BT_box ||
      (btype != BoundingVolume::BT_sphere && all_box)) {
    // If all of the child volumes are a BoundingBox, then our volume is also
    // a BoundingBox.
    gbv = new BoundingBox;
  } else {
    // Otherwise, it's a sphere.
    gbv = new BoundingSphere;
  }

  if (child_volumes.size() > 0) {
    const BoundingVolume **child_begin = &child_volumes[0];
    const BoundingVolume **child_end = child_begin + child_volumes.size();
    ((BoundingVolume *)gbv)->around(child_begin, child_end);
  }

  internal_bounds = gbv;
  internal_vertices = 0;
}

/**
 * Returns a RenderState for rendering the ghosted collision solid that
 * represents the previous frame's position, for those collision nodes that
 * indicate a velocity.
 */
CPT(RenderState) CollisionNode::
get_last_pos_state() {
  // Once someone asks for this pointer, we hold its reference count and never
  // free it.
  static CPT(RenderState) state = nullptr;
  if (state == nullptr) {
    state = RenderState::make
      (ColorScaleAttrib::make(LVecBase4(1.0f, 1.0f, 1.0f, 0.5f)),
       TransparencyAttrib::make(TransparencyAttrib::M_alpha));
  }

  return state;
}


/**
 * Tells the BamReader how to create objects of type CollisionNode.
 */
void CollisionNode::
register_with_read_factory() {
  BamReader::get_factory()->register_factory(get_class_type(), make_from_bam);
}

/**
 * Writes the contents of this object to the datagram for shipping out to a
 * Bam file.
 */
void CollisionNode::
write_datagram(BamWriter *manager, Datagram &dg) {
  PandaNode::write_datagram(manager, dg);

  int num_solids = _solids.size();
  if (num_solids >= 0xffff) {
    dg.add_uint16(0xffff);
    dg.add_uint32(num_solids);
  } else {
    dg.add_uint16(num_solids);
  }
  for(int i = 0; i < num_solids; i++) {
    manager->write_pointer(dg, _solids[i].get_read_pointer());
  }

  dg.add_uint32(_from_collide_mask.get_word());
}

/**
 * Receives an array of pointers, one for each time manager->read_pointer()
 * was called in fillin(). Returns the number of pointers processed.
 */
int CollisionNode::
complete_pointers(TypedWritable **p_list, BamReader *manager) {
  int pi = PandaNode::complete_pointers(p_list, manager);

  int num_solids = _solids.size();
  for (int i = 0; i < num_solids; i++) {
    _solids[i] = DCAST(CollisionSolid, p_list[pi++]);
  }

  return pi;
}

/**
 * This function is called by the BamReader's factory when a new object of
 * type CollisionNode is encountered in the Bam file.  It should create the
 * CollisionNode and extract its information from the file.
 */
TypedWritable *CollisionNode::
make_from_bam(const FactoryParams &params) {
  CollisionNode *node = new CollisionNode("");
  DatagramIterator scan;
  BamReader *manager;

  parse_params(params, scan, manager);
  node->fillin(scan, manager);

  return node;
}

/**
 * This internal function is called by make_from_bam to read in all of the
 * relevant data from the BamFile for the new CollisionNode.
 */
void CollisionNode::
fillin(DatagramIterator &scan, BamReader *manager) {
  PandaNode::fillin(scan, manager);

  int num_solids = scan.get_uint16();
  if (num_solids == 0xffff) {
    num_solids = scan.get_uint32();
  }
  _solids.clear();
  _solids.reserve(num_solids);
  for(int i = 0; i < num_solids; i++) {
    manager->read_pointer(scan);
    // Push back a NULL for each solid, for now.  We'll fill them in later.
    _solids.push_back(nullptr);
  }

  _from_collide_mask.set_word(scan.get_uint32());
}