source: trunk/packages/vizservers/vtkvis/ColorMap.h @ 2238

/* -*- mode: c++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
 * Copyright (C) 2011, Purdue Research Foundation
 *
 * Author: Leif Delgass <ldelgass@purdue.edu>
 */

#ifndef __RAPPTURE_VTKVIS_COLORMAP_H__
#define __RAPPTURE_VTKVIS_COLORMAP_H__

#include <string>
#include <list>
#include <cstring>
#include <vtkSmartPointer.h>
#include <vtkLookupTable.h>

namespace Rappture {
namespace VtkVis {

/**
 * \brief RGBA color map table created from transfer function
 *
 * ColorMap uses linear interpolation between ControlPoints to
 * create a color lookup table for VTK
 */
class ColorMap {
public:
    /**
     * \brief RGB inflection point in a transfer function
     */
    struct ControlPoint {
        ControlPoint() :
            value(0)
        {
            memset(color, 0, sizeof(double)*3);
        }
        ControlPoint(const ControlPoint& other) :
            value(other.value)
        {
            memcpy(color, other.color, sizeof(double)*3);
        }
        ControlPoint& operator=(const ControlPoint &other)
        {
            if (this != &other) {
                value = other.value;
                memcpy(color, other.color, sizeof(double)*3);
            }
            return *this;
        }

        double value; ///< Normalized scalar data value [0,1]
        double color[3]; ///< RGB color
    };

    /**
     * \brief Opacity(alpha) inflection point in a transfer function
     */
    struct OpacityControlPoint {
        OpacityControlPoint() :
            value(0),
            alpha(1)
        {
        }
        OpacityControlPoint(const OpacityControlPoint& other) :
            value(other.value),
            alpha(other.alpha)
        {
        }
        OpacityControlPoint& operator=(const OpacityControlPoint &other)
        {
            if (this != &other) {
                value = other.value;
                alpha = other.alpha;
            }
            return *this;
        }

        double value; ///< Normalized scalar data value [0,1]
        double alpha; ///< Opacity
    };

    ColorMap(const std::string& name);
    virtual ~ColorMap();

    const std::string& getName();
    vtkLookupTable *getLookupTable();

    void setNumberOfTableEntries(int numEntries);

    void addControlPoint(ControlPoint& cp);

    void addOpacityControlPoint(OpacityControlPoint& cp);

    void build();

    void clear();

    static ColorMap* createDefault();

private:
    ColorMap();

    void lerp(double *result, const ControlPoint& cp1, const ControlPoint& cp2, double value);
    void lerp(double *result, const OpacityControlPoint& cp1, const OpacityControlPoint& cp2, double value);

    std::string _name;
    std::list<ControlPoint> _controlPoints;
    std::list<OpacityControlPoint> _opacityControlPoints;
    bool _needsBuild;
    int _numTableEntries;
    vtkSmartPointer<vtkLookupTable> _lookupTable;
};

}
}

#endif