122 lines
3.8 KiB
C++
122 lines
3.8 KiB
C++
/**
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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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* @file depthOffsetAttrib.h
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* @author drose
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* @date 2002-03-14
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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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* This is a special kind of attribute that instructs the graphics driver to
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* apply an offset or bias to the generated depth values for rendered
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* polygons, before they are written to the depth buffer.
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*
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* This can be used to shift polygons forward slightly, to resolve depth
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* conflicts. The cull traverser may optionally use this, for instance, to
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* implement decals. However, driver support for this feature seems to be
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* spotty, so use with caution.
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*
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* The bias is always an integer number, and each integer increment represents
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* the smallest possible increment in Z that is sufficient to completely
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* resolve two coplanar polygons. Positive numbers are closer towards the
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* camera.
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*
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* Nested DepthOffsetAttrib values accumulate; that is, a DepthOffsetAttrib
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* with a value of 1 beneath another DepthOffsetAttrib with a value of 2
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* presents a net offset of 3. (A DepthOffsetAttrib will not, however,
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* combine with any other DepthOffsetAttribs with a lower override parameter.)
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* The net value should 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 DepthOffsetAttrib can be used to
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* constrain the Z output value to a subset of the usual [0, 1] range (or
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* reversing its direction) by specifying a new 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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PUBLISHED:
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MAKE_PROPERTY(offset, get_offset);
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MAKE_PROPERTY(min_value, get_min_value);
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MAKE_PROPERTY(max_value, get_max_value);
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public:
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virtual void output(std::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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MAKE_PROPERTY(class_slot, get_class_slot);
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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,
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new DepthOffsetAttrib(0, 0, 1));
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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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