126 lines
4.3 KiB
C++
126 lines
4.3 KiB
C++
// Filename: depthOffsetAttrib.h
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// Created by: drose (14Mar02)
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//
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////////////////////////////////////////////////////////////////////
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//
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// PANDA 3D SOFTWARE
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// Copyright (c) Carnegie Mellon University. All rights reserved.
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//
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// All use of this software is subject to the terms of the revised BSD
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// license. You should have received a copy of this license along
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// with this source code in a file named "LICENSE."
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//
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////////////////////////////////////////////////////////////////////
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#ifndef DEPTHOFFSETATTRIB_H
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#define DEPTHOFFSETATTRIB_H
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#include "pandabase.h"
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#include "renderAttrib.h"
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#include "luse.h"
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class FactoryParams;
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////////////////////////////////////////////////////////////////////
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// Class : DepthOffsetAttrib
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// Description : This is a special kind of attribute that instructs
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// the graphics driver to apply an offset or bias to the
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// generated depth values for rendered polygons, before
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// they are written to the depth buffer.
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//
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// This can be used to shift polygons forward slightly,
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// to resolve depth conflicts. The cull traverser may
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// optionally use this, for instance, to implement
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// decals. However, driver support for this feature
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// seems to be spotty, so use with caution.
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//
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// The bias is always an integer number, and each
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// integer increment represents the smallest possible
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// increment in Z that is sufficient to completely
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// resolve two coplanar polygons. Positive numbers are
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// closer towards the camera.
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//
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// Nested DepthOffsetAttrib values accumulate; that is,
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// a DepthOffsetAttrib with a value of 1 beneath another
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// DepthOffsetAttrib with a value of 2 presents a net
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// offset of 3. (A DepthOffsetAttrib will not, however,
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// combine with any other DepthOffsetAttribs with a
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// lower override parameter.) The net value should
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// probably not exceed 16 or drop below 0 for maximum
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// portability.
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//
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// Also, and only tangentially related, the
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// DepthOffsetAttrib can be used to constrain the Z
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// output value to a subset of the usual [0, 1] range
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// (or reversing its direction) by specifying a new
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// min_value and max_value.
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////////////////////////////////////////////////////////////////////
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class EXPCL_PANDA_PGRAPH DepthOffsetAttrib : public RenderAttrib {
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private:
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INLINE DepthOffsetAttrib(int offset, PN_stdfloat min_value, PN_stdfloat max_value);
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PUBLISHED:
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static CPT(RenderAttrib) make(int offset = 1);
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static CPT(RenderAttrib) make(int offset, PN_stdfloat min_value, PN_stdfloat max_value);
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static CPT(RenderAttrib) make_default();
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INLINE int get_offset() const;
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INLINE PN_stdfloat get_min_value() const;
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INLINE PN_stdfloat get_max_value() const;
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public:
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virtual void output(ostream &out) const;
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protected:
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virtual int compare_to_impl(const RenderAttrib *other) const;
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virtual size_t get_hash_impl() const;
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virtual CPT(RenderAttrib) compose_impl(const RenderAttrib *other) const;
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virtual CPT(RenderAttrib) invert_compose_impl(const RenderAttrib *other) const;
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private:
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int _offset;
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PN_stdfloat _min_value;
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PN_stdfloat _max_value;
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PUBLISHED:
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static int get_class_slot() {
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return _attrib_slot;
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}
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virtual int get_slot() const {
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return get_class_slot();
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}
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public:
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static void register_with_read_factory();
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virtual void write_datagram(BamWriter *manager, Datagram &dg);
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protected:
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static TypedWritable *make_from_bam(const FactoryParams ¶ms);
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void fillin(DatagramIterator &scan, BamReader *manager);
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public:
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static TypeHandle get_class_type() {
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return _type_handle;
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}
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static void init_type() {
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RenderAttrib::init_type();
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register_type(_type_handle, "DepthOffsetAttrib",
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RenderAttrib::get_class_type());
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_attrib_slot = register_slot(_type_handle, 100, make_default);
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}
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virtual TypeHandle get_type() const {
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return get_class_type();
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}
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virtual TypeHandle force_init_type() {init_type(); return get_class_type();}
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private:
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static TypeHandle _type_handle;
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static int _attrib_slot;
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};
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#include "depthOffsetAttrib.I"
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#endif
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