depthOffsetAttrib.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 depthOffsetAttrib.cxx
 * @author drose
 * @date 2002-03-14
 */

#include "depthOffsetAttrib.h"
#include "graphicsStateGuardianBase.h"
#include "dcast.h"
#include "bamReader.h"
#include "bamWriter.h"
#include "datagram.h"
#include "datagramIterator.h"

TypeHandle DepthOffsetAttrib::_type_handle;
int DepthOffsetAttrib::_attrib_slot;

/**
 * Constructs a new DepthOffsetAttrib object that indicates the relative
 * amount of bias to write to the depth buffer for subsequent geometry.
 */
CPT(RenderAttrib) DepthOffsetAttrib::
make(int offset) {
  DepthOffsetAttrib *attrib = new DepthOffsetAttrib(offset, 0.0f, 1.0f);
  return return_new(attrib);
}

/**
 * Constructs a new DepthOffsetAttrib object that indicates the bias, and also
 * specifies a minimum and maximum (or, more precisely, nearest and farthest)
 * values to write to the depth buffer, in the range 0 .. 1.  This range is 0,
 * 1 by default; setting it to some other range can be used to create
 * additional depth buffer effects.
 */
CPT(RenderAttrib) DepthOffsetAttrib::
make(int offset, PN_stdfloat min_value, PN_stdfloat max_value) {
  nassertr(min_value >= 0.0f && min_value <= 1.0f, nullptr);
  nassertr(max_value >= 0.0f && max_value <= 1.0f, nullptr);
  DepthOffsetAttrib *attrib = new DepthOffsetAttrib(offset, min_value, max_value);
  return return_new(attrib);
}

/**
 * Returns a RenderAttrib that corresponds to whatever the standard default
 * properties for render attributes of this type ought to be.
 */
CPT(RenderAttrib) DepthOffsetAttrib::
make_default() {
  return return_new(new DepthOffsetAttrib(0, 0.0f, 1.0f));
}

/**
 *
 */
void DepthOffsetAttrib::
output(std::ostream &out) const {
  out << get_type() << ":(" << get_offset() << ", " << get_min_value()
      << ", " << get_max_value() << ")";
}

/**
 * Intended to be overridden by derived DepthOffsetAttrib types to return a
 * unique number indicating whether this DepthOffsetAttrib is equivalent to
 * the other one.
 *
 * This should return 0 if the two DepthOffsetAttrib 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 DepthOffsetAttrib objects whose
 * get_type() functions return the same.
 */
int DepthOffsetAttrib::
compare_to_impl(const RenderAttrib *other) const {
  const DepthOffsetAttrib *ta = (const DepthOffsetAttrib *)other;

  if (_offset != ta->_offset) {
    return _offset - ta->_offset;
  }
  if (_min_value != ta->_min_value) {
    return _min_value < ta->_min_value ? -1 : 1;
  }
  if (_max_value != ta->_max_value) {
    return _max_value < ta->_max_value ? -1 : 1;
  }
  return 0;
}

/**
 * Intended to be overridden by derived RenderAttrib types to return a unique
 * hash for these particular properties.  RenderAttribs that compare the same
 * with compare_to_impl(), above, should return the same hash; RenderAttribs
 * that compare differently should return a different hash.
 */
size_t DepthOffsetAttrib::
get_hash_impl() const {
  size_t hash = 0;
  hash = int_hash::add_hash(hash, _offset);
  hash = float_hash().add_hash(hash, _min_value);
  hash = float_hash().add_hash(hash, _max_value);
  return hash;
}

/**
 * Intended to be overridden by derived RenderAttrib types to specify how two
 * consecutive RenderAttrib objects of the same type interact.
 *
 * This should return the result of applying the other RenderAttrib to a node
 * in the scene graph below this RenderAttrib, which was already applied.  In
 * most cases, the result is the same as the other RenderAttrib (that is, a
 * subsequent RenderAttrib completely replaces the preceding one).  On the
 * other hand, some kinds of RenderAttrib (for instance, ColorTransformAttrib)
 * might combine in meaningful ways.
 */
CPT(RenderAttrib) DepthOffsetAttrib::
compose_impl(const RenderAttrib *other) const {
  const DepthOffsetAttrib *ta = (const DepthOffsetAttrib *)other;

  int new_offset = ta->_offset + _offset;

  DepthOffsetAttrib *attrib = new DepthOffsetAttrib(new_offset, ta->_min_value, ta->_max_value);
  return return_new(attrib);
}

/**
 * Intended to be overridden by derived RenderAttrib types to specify how two
 * consecutive RenderAttrib objects of the same type interact.
 *
 * See invert_compose() and compose_impl().
 */
CPT(RenderAttrib) DepthOffsetAttrib::
invert_compose_impl(const RenderAttrib *other) const {
  const DepthOffsetAttrib *ta = (const DepthOffsetAttrib *)other;

  int new_offset = ta->_offset - _offset;

  DepthOffsetAttrib *attrib = new DepthOffsetAttrib(new_offset, ta->_min_value, ta->_max_value);
  return return_new(attrib);
}

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

  dg.add_int32(_offset);
  if (manager->get_file_minor_ver() >= 31) {
    dg.add_stdfloat(_min_value);
    dg.add_stdfloat(_max_value);
  }
}

/**
 * This function is called by the BamReader's factory when a new object of
 * type DepthOffsetAttrib is encountered in the Bam file.  It should create
 * the DepthOffsetAttrib and extract its information from the file.
 */
TypedWritable *DepthOffsetAttrib::
make_from_bam(const FactoryParams &params) {
  DepthOffsetAttrib *attrib = new DepthOffsetAttrib(0, 0.0f, 1.0f);
  DatagramIterator scan;
  BamReader *manager;

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

  return attrib;
}

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

  _offset = scan.get_int32();
  _min_value = 0.0f;
  _max_value = 1.0f;
  if (manager->get_file_minor_ver() >= 31) {
    _min_value = scan.get_stdfloat();
    _max_value = scan.get_stdfloat();
  }
}