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/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
*
* This library is open source and may be redistributed and/or modified under
* the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
* (at your option) any later version. The full license is in LICENSE file
* included with this distribution, and on the openscenegraph.org website.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* OpenSceneGraph Public License for more details.
*/
#ifndef OSG_TRANSFERFUNCTION
#define OSG_TRANSFERFUNCTION 1
#include <osg/Texture>
#include <osg/Shader>
#include <map>
namespace osg {
/** TransferFunction is a class that provide a 1D,2D or 3D colour look up table
* that can be used on the GPU as a 1D, 2D or 3D texture.
* Typically uses include mapping heights to colours when contouring terrain,
* or mapping intensities to colours when volume rendering.
*/
class OSG_EXPORT TransferFunction : public osg::Object
{
public :
TransferFunction();
/** Copy constructor using CopyOp to manage deep vs shallow copy.*/
TransferFunction(const TransferFunction& tf, const CopyOp& copyop=CopyOp::SHALLOW_COPY);
META_Object(osg, TransferFunction)
/** Get the image that is used for passing the transfer function data to the GPU.*/
osg::Image* getImage() { return _image.get(); }
/** Get the const image that is used for passing the transfer function data to the GPU.*/
const osg::Image* getImage() const { return _image.get(); }
protected:
virtual ~TransferFunction();
osg::ref_ptr<osg::Image> _image;
};
/** 1D variant of TransferFunction. */
class OSG_EXPORT TransferFunction1D : public osg::TransferFunction
{
public:
TransferFunction1D();
/** Copy constructor using CopyOp to manage deep vs shallow copy.*/
TransferFunction1D(const TransferFunction1D& tf, const CopyOp& copyop=CopyOp::SHALLOW_COPY);
META_Object(osg, TransferFunction1D)
/** Get the minimum transfer function value.*/
float getMinimum() const { return _colorMap.empty() ? 0.0f : _colorMap.begin()->first; }
/** Get the maximum transfer function value.*/
float getMaximum() const { return _colorMap.empty() ? 0.0f : _colorMap.rbegin()->first; }
/** allocate the osg::Image with specified dimension. The Image tracks the color map, and is used to represent the
* transfer function when download to GPU.*/
void allocate(unsigned int numImageCells);
/** Clear the whole range to just represent a single color.*/
void clear(const osg::Vec4& color = osg::Vec4(1.0f,1.0f,1.0f,1.0f));
/** Get pixel value from the image. */
osg::Vec4 getPixelValue(unsigned int i) const
{
if (_image.valid() && i<static_cast<unsigned int>(_image->s()))
{
return *reinterpret_cast<osg::Vec4*>(_image->data(i));
}
else
{
return osg::Vec4(1.0f,1.0f,1.0f,1.0f);
}
}
/** Get the number of image cells that are assigned to the represent the transfer function when download to the GPU.*/
unsigned int getNumberImageCells() const { return _image.valid() ? _image->s() : 0; }
/** Set the color for a specified transfer function value.
* updateImage defaults to true, and tells the setColor function to update the associate osg::Image that
* tracks the color map. Pass in false as the updateImage parameter if you are setting up many values
* at once to avoid recomputation of the image data, then once all setColor calls are made explictly call
* updateImage() to bring the osg::Image back into sync with the color map. */
void setColor(float v, const osg::Vec4& color, bool updateImage=true);
/** Get the color for a specified transfer function value, interpolating the value if no exact match is found.*/
osg::Vec4 getColor(float v) const;
typedef std::map<float, osg::Vec4> ColorMap;
/** Get the color map that stores the mapping between the the transfer function value and the colour it maps to.*/
ColorMap& getColorMap() { return _colorMap; }
/** Get the const color map that stores the mapping between the the transfer function value and the colour it maps to.*/
const ColorMap& getColorMap() const { return _colorMap; }
/** Assign a color map and automatically update the image to make sure they are in sync.*/
void assign(const ColorMap& vcm);
/** Manually update the associate osg::Image to represent the colors assigned in the color map.*/
void updateImage();
protected:
ColorMap _colorMap;
void assignToImage(float lower_v, const osg::Vec4& lower_c, float upper_v, const osg::Vec4& upper_c);
};
}
#endif
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