compassEffect.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 compassEffect.cxx
 * @author drose
 * @date 2002-07-16
 */

#include "compassEffect.h"
#include "cullTraverserData.h"
#include "config_pgraph.h"
#include "nodePath.h"
#include "bamReader.h"
#include "bamWriter.h"
#include "datagram.h"
#include "datagramIterator.h"

TypeHandle CompassEffect::_type_handle;

/**
 * Constructs a new CompassEffect object.  If the reference is an empty
 * NodePath, it means the CompassEffect is relative to the root of the scene
 * graph; otherwise, it's relative to the indicated node.  The properties
 * bitmask specifies the set of properties that the compass node inherits from
 * the reference instead of from its parent.
 */
CPT(RenderEffect) CompassEffect::
make(const NodePath &reference, int properties) {
  CompassEffect *effect = new CompassEffect;
  effect->_reference = reference;
  effect->_properties = (properties & P_all);
  return return_new(effect);
}

/**
 * Returns true if it is generally safe to transform this particular kind of
 * RenderEffect by calling the xform() method, false otherwise.
 */
bool CompassEffect::
safe_to_transform() const {
  return false;
}

/**
 *
 */
void CompassEffect::
output(std::ostream &out) const {
  out << get_type() << ":";
  if (_properties == 0) {
    out << " none";
  }
  if ((_properties & P_pos) == P_pos) {
    out << " xyz";
  } else {
    if ((_properties & P_x) != 0) {
      out << " x";
    }
    if ((_properties & P_y) != 0) {
      out << " y";
    }
    if ((_properties & P_z) != 0) {
      out << " z";
    }
  }
  if ((_properties & P_rot) != 0) {
    out << " rot";
  }
  if ((_properties & P_scale) == P_scale) {
    out << " scale";
  } else {
    if ((_properties & P_sx) != 0) {
      out << " sx";
    }
    if ((_properties & P_sy) != 0) {
      out << " sy";
    }
    if ((_properties & P_sz) != 0) {
      out << " sz";
    }
  }
  if (!_reference.is_empty()) {
    out << " reference " << _reference;
  }
}

/**
 * Should be overridden by derived classes to return true if cull_callback()
 * has been defined.  Otherwise, returns false to indicate cull_callback()
 * does not need to be called for this effect during the cull traversal.
 */
bool CompassEffect::
has_cull_callback() const {
  return true;
}

/**
 * If has_cull_callback() returns true, 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.
 *
 * At the time this function is called, the current node's transform and state
 * have not yet been applied to the net_transform and net_state.  This
 * callback may modify the node_transform and node_state to apply an effective
 * change to the render state at this level.
 */
void CompassEffect::
cull_callback(CullTraverser *trav, CullTraverserData &data,
              CPT(TransformState) &node_transform,
              CPT(RenderState) &) const {
  if (_properties == 0) {
    // Nothing to do.
    return;
  }

  CPT(TransformState) true_net_transform = data.get_net_transform(trav);
  CPT(TransformState) want_net_transform = true_net_transform;
  adjust_transform(want_net_transform, node_transform, data.node());

  // Now compute the transform that will convert true_net_transform to
  // want_transform.  This is inv(true_net_transform) * want_transform.
  CPT(TransformState) compass_transform =
    true_net_transform->invert_compose(want_net_transform);

  // And modify our local node's apparent transform so that
  // true_net_transform->compose(new_node_transform) produces the same result
  // we would have gotten had we actually computed
  // want_transform->compose(orig_node_transform).
  node_transform = compass_transform->compose(node_transform);
}

/**
 * Should be overridden by derived classes to return true if
 * adjust_transform() has been defined, and therefore the RenderEffect has
 * some effect on the node's apparent local and net transforms.
 */
bool CompassEffect::
has_adjust_transform() const {
  return (_properties != 0);
}

/**
 * Performs some operation on the node's apparent net and/or local transforms.
 * This will only be called if has_adjust_transform() is redefined to return
 * true.
 *
 * Both parameters are in/out.  The original transforms will be passed in, and
 * they may (or may not) be modified in-place by the RenderEffect.
 */
void CompassEffect::
adjust_transform(CPT(TransformState) &net_transform,
                 CPT(TransformState) &node_transform,
                 const PandaNode *) const {
  if (_properties == 0) {
    // Nothing to do.
    return;
  }

  // The reference transform: where we are acting as if we inherit from.
  // Either the root node (identity) or the specified reference node.
  CPT(TransformState) ref_transform;
  if (_reference.is_empty()) {
    ref_transform = TransformState::make_identity();
  } else {
    ref_transform = _reference.get_net_transform();
  }

  // Now compute the net transform we actually want to achieve.  This is all
  // of the components from the net transform we want to inherit normally from
  // our parent, with all of the components from the ref transform we want to
  // inherit from our reference.
  CPT(TransformState) want_net_transform;
  if (_properties == P_all) {
    // If we want to steal the whole transform, that's easy.
    want_net_transform = ref_transform;

  } else {
    // How much of the pos do we want to steal?  We can always determine a
    // transform's pos, even if it's nondecomposable.
    LVecBase3 want_pos = net_transform->get_pos();
    const LVecBase3 &ref_pos = ref_transform->get_pos();
    if ((_properties & P_x) != 0) {
      want_pos[0] = ref_pos[0];
    }
    if ((_properties & P_y) != 0) {
      want_pos[1] = ref_pos[1];
    }
    if ((_properties & P_z) != 0) {
      want_pos[2] = ref_pos[2];
    }

    if ((_properties & ~P_pos) == 0) {
      // If we only want to steal the pos, that's pretty easy.
      want_net_transform = net_transform->set_pos(want_pos);

    } else if ((_properties & (P_rot | P_scale)) == (P_rot | P_scale)) {
      // If we want to steal everything *but* the pos, also easy.
      want_net_transform = ref_transform->set_pos(want_pos);

    } else {
      // For any other combination, we have to be able to decompose both
      // transforms.
      if (!net_transform->has_components() ||
          !ref_transform->has_components()) {
        // If we can't decompose, just do the best we can: steal everything
        // but the pos.
        want_net_transform = ref_transform->set_pos(want_pos);

      } else {
        // If we can decompose, then take only the components we want.
        LQuaternion want_quat = net_transform->get_quat();
        if ((_properties & P_rot) != 0) {
          want_quat = ref_transform->get_quat();
        }

        LVecBase3 want_scale = net_transform->get_scale();
        const LVecBase3 &ref_scale = ref_transform->get_scale();
        if ((_properties & P_sx) != 0) {
          want_scale[0] = ref_scale[0];
        }
        if ((_properties & P_sy) != 0) {
          want_scale[1] = ref_scale[1];
        }
        if ((_properties & P_sz) != 0) {
          want_scale[2] = ref_scale[2];
        }

        want_net_transform =
          TransformState::make_pos_quat_scale(want_pos, want_quat, want_scale);
      }
    }
  }

  net_transform = want_net_transform;
}

/**
 * Intended to be overridden by derived CompassEffect types to return a unique
 * number indicating whether this CompassEffect is equivalent to the other
 * one.
 *
 * This should return 0 if the two CompassEffect objects are equivalent, a
 * number less than zero if this one should be sorted before the other one,
 * and a number greater than zero otherwise.
 *
 * This will only be called with two CompassEffect objects whose get_type()
 * functions return the same.
 */
int CompassEffect::
compare_to_impl(const RenderEffect *other) const {
  const CompassEffect *ta;
  DCAST_INTO_R(ta, other, 0);

  if (_properties != ta->_properties) {
    return _properties - ta->_properties;
  }
  int compare = _reference.compare_to(ta->_reference);
  if (compare != 0) {
    return compare;
  }
  return 0;
}

/**
 * Tells the BamReader how to create objects of type CompassEffect.
 */
void CompassEffect::
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 CompassEffect::
write_datagram(BamWriter *manager, Datagram &dg) {
  RenderEffect::write_datagram(manager, dg);
  dg.add_uint16(_properties);

  if (manager->get_file_minor_ver() >= 43) {
    _reference.write_datagram(manager, dg);
  }
}

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

  if (manager->get_file_minor_ver() >= 43) {
    pi += _reference.complete_pointers(p_list + pi, manager);
  }

  return pi;
}

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

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

  return effect;
}

/**
 * This internal function is called by make_from_bam to read in all of the
 * relevant data from the BamFile for the new CompassEffect.
 */
void CompassEffect::
fillin(DatagramIterator &scan, BamReader *manager) {
  RenderEffect::fillin(scan, manager);
  _properties = scan.get_uint16();

  if (manager->get_file_minor_ver() >= 43) {
    _reference.fillin(scan, manager);
  }
}