collisionSegment.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 collisionSegment.cxx
 * @author drose
 * @date 2001-01-30
 */

#include "collisionSegment.h"
#include "collisionHandler.h"
#include "collisionEntry.h"
#include "config_collide.h"
#include "geom.h"
#include "lensNode.h"
#include "geomNode.h"
#include "lens.h"
#include "geometricBoundingVolume.h"
#include "datagram.h"
#include "datagramIterator.h"
#include "bamReader.h"
#include "bamWriter.h"
#include "geom.h"
#include "geomLines.h"
#include "boundingSphere.h"
#include "boundingHexahedron.h"
#include "geomVertexWriter.h"
#include "look_at.h"

TypeHandle CollisionSegment::_type_handle;


/**
 *
 */
CollisionSolid *CollisionSegment::
make_copy() {
  return new CollisionSegment(*this);
}

/**
 *
 */
PT(CollisionEntry) CollisionSegment::
test_intersection(const CollisionEntry &entry) const {
  return entry.get_into()->test_intersection_from_segment(entry);
}

/**
 * Transforms the solid by the indicated matrix.
 */
void CollisionSegment::
xform(const LMatrix4 &mat) {
  _a = _a * mat;
  _b = _b * mat;

  CollisionSolid::xform(mat);
}

/**
 * Returns the point in space deemed to be the "origin" of the solid for
 * collision purposes.  The closest intersection point to this origin point is
 * considered to be the most significant.
 */
LPoint3 CollisionSegment::
get_collision_origin() const {
  return get_point_a();
}

/**
 *
 */
void CollisionSegment::
output(std::ostream &out) const {
  out << "segment, a (" << _a << "), b (" << _b << ")";
}

/**
 * Accepts a LensNode and a 2-d point in the range [-1,1].  Sets the
 * CollisionSegment so that it begins at the LensNode's near plane and extends
 * to the far plane, making it suitable for picking objects from the screen
 * given a camera and a mouse location.
 *
 * Returns true if the point was acceptable, false otherwise.
 */
bool CollisionSegment::
set_from_lens(LensNode *camera, const LPoint2 &point) {
  Lens *proj = camera->get_lens();

  bool success = true;
  if (!proj->extrude(point, _a, _b)) {
    _a = LPoint3::origin();
    _b = _a + LVector3::forward();
    success = false;
  }

  mark_internal_bounds_stale();
  mark_viz_stale();

  return success;
}

/**
 *
 */
PT(BoundingVolume) CollisionSegment::
compute_internal_bounds() const {

  LVector3 pdelta = _b - _a;

  // If p1 and p2 are sufficiently close, just put a sphere around them.
  PN_stdfloat d2 = pdelta.length_squared();
  if (d2 < collision_parabola_bounds_threshold * collision_parabola_bounds_threshold) {
    LPoint3 pmid = (_a + _b) * 0.5f;
    return new BoundingSphere(pmid, csqrt(d2) * 0.5f);
  }

  LMatrix4 from_segment;
  look_at(from_segment, pdelta, LPoint3(0,0,1), CS_zup_right);
  from_segment.set_row(3, _a);

  PN_stdfloat max_y =  sqrt(d2) + 0.01;
  PT(BoundingHexahedron) volume =
    new BoundingHexahedron(LPoint3(-0.01, max_y, -0.01), LPoint3(0.01, max_y, -0.01),
                           LPoint3(0.01, max_y, 0.01), LPoint3(-0.01, max_y,  0.01),
                           LPoint3(-0.01, -0.01, -0.01), LPoint3(0.01, 0.01, -0.01),
                           LPoint3(0.01, -0.01, 0.01), LPoint3(-0.01, -0.01, 0.01));

  volume->xform(from_segment);
  return volume;
}

/**
 * Fills the _viz_geom GeomNode up with Geoms suitable for rendering this
 * solid.
 */
void CollisionSegment::
fill_viz_geom() {
  if (collide_cat.is_debug()) {
    collide_cat.debug()
      << "Recomputing viz for " << *this << "\n";
  }

  PT(GeomVertexData) vdata = new GeomVertexData
    ("collision", GeomVertexFormat::get_v3cp(),
     Geom::UH_static);
  GeomVertexWriter vertex(vdata, InternalName::get_vertex());

  vertex.add_data3(_a);
  vertex.add_data3(_b);

  PT(GeomLines) line = new GeomLines(Geom::UH_static);
  line->add_next_vertices(2);
  line->close_primitive();

  PT(Geom) geom = new Geom(vdata);
  geom->add_primitive(line);

  _viz_geom->add_geom(geom, get_other_viz_state());
  _bounds_viz_geom->add_geom(geom, get_other_bounds_viz_state());
}

/**
 * Tells the BamReader how to create objects of type CollisionSegment.
 */
void CollisionSegment::
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 CollisionSegment::
write_datagram(BamWriter *manager, Datagram &dg) {
  CollisionSolid::write_datagram(manager, dg);
  _a.write_datagram(dg);
  _b.write_datagram(dg);
}

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