1/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
3 * This library is open source and may be redistributed and/or modified under
4 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
5 * (at your option) any later version. The full license is in LICENSE file
6 * included with this distribution, and on the openscenegraph.org website.
8 * This library is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * OpenSceneGraph Public License for more details.
14#ifndef OSG_TRANSFERFUNCTION
15#define OSG_TRANSFERFUNCTION 1
25/** TransferFunction is a class that provide a 1D,2D or 3D colour look up table
26 * that can be used on the GPU as a 1D, 2D or 3D texture.
27 * Typically uses include mapping heights to colours when contouring terrain,
28 * or mapping intensities to colours when volume rendering.
30class OSG_EXPORT TransferFunction : public osg::Object
36 /** Copy constructor using CopyOp to manage deep vs shallow copy.*/
37 TransferFunction(const TransferFunction& tf, const CopyOp& copyop=CopyOp::SHALLOW_COPY);
39 META_Object(osg, TransferFunction)
41 /** Get the image that is used for passing the transfer function data to the GPU.*/
42 osg::Image* getImage() { return _image.get(); }
44 /** Get the const image that is used for passing the transfer function data to the GPU.*/
45 const osg::Image* getImage() const { return _image.get(); }
49 virtual ~TransferFunction();
51 osg::ref_ptr<osg::Image> _image;
54/** 1D variant of TransferFunction. */
55class OSG_EXPORT TransferFunction1D : public osg::TransferFunction
61 /** Copy constructor using CopyOp to manage deep vs shallow copy.*/
62 TransferFunction1D(const TransferFunction1D& tf, const CopyOp& copyop=CopyOp::SHALLOW_COPY);
64 META_Object(osg, TransferFunction1D)
66 /** Get the minimum transfer function value.*/
67 float getMinimum() const { return _colorMap.empty() ? 0.0f : _colorMap.begin()->first; }
69 /** Get the maximum transfer function value.*/
70 float getMaximum() const { return _colorMap.empty() ? 0.0f : _colorMap.rbegin()->first; }
72 /** allocate the osg::Image with specified dimension. The Image tracks the color map, and is used to represent the
73 * transfer function when download to GPU.*/
74 void allocate(unsigned int numImageCells);
76 /** Clear the whole range to just represent a single color.*/
77 void clear(const osg::Vec4& color = osg::Vec4(1.0f,1.0f,1.0f,1.0f));
79 /** Get pixel value from the image. */
80 osg::Vec4 getPixelValue(unsigned int i) const
82 if (_image.valid() && i<static_cast<unsigned int>(_image->s()))
84 return *reinterpret_cast<osg::Vec4*>(_image->data(i));
88 return osg::Vec4(1.0f,1.0f,1.0f,1.0f);
92 /** Get the number of image cells that are assigned to the represent the transfer function when download to the GPU.*/
93 unsigned int getNumberImageCells() const { return _image.valid() ? _image->s() : 0; }
95 /** Set the color for a specified transfer function value.
96 * updateImage defaults to true, and tells the setColor function to update the associate osg::Image that
97 * tracks the color map. Pass in false as the updateImage parameter if you are setting up many values
98 * at once to avoid recomputation of the image data, then once all setColor calls are made explicitly call
99 * updateImage() to bring the osg::Image back into sync with the color map. */
100 void setColor(float v, const osg::Vec4& color, bool updateImage=true);
102 /** Get the color for a specified transfer function value, interpolating the value if no exact match is found.*/
103 osg::Vec4 getColor(float v) const;
105 typedef std::map<float, osg::Vec4> ColorMap;
107 /** set the color map and automatically update the image to make sure they are in sync.*/
108 void setColorMap(const ColorMap& vcm) { assign(vcm); }
110 /** Get the color map that stores the mapping between the transfer function value and the colour it maps to.*/
111 ColorMap& getColorMap() { return _colorMap; }
113 /** Get the const color map that stores the mapping between the transfer function value and the colour it maps to.*/
114 const ColorMap& getColorMap() const { return _colorMap; }
116 /** Assign a color map and automatically update the image to make sure they are in sync.*/
117 void assign(const ColorMap& vcm);
119 /** Manually update the associate osg::Image to represent the colors assigned in the color map.*/
126 void assignToImage(float lower_v, const osg::Vec4& lower_c, float upper_v, const osg::Vec4& upper_c);