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sglUnScaleRange.hpp

/*****************************************************************************
 * SGL: A Scene Graph Library
 *
 * Copyright (C) 1997-2001  Scott McMillan   All Rights Reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * 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 GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *****************************************************************************
 *     File: sglUnScaleRange.hpp
 *   Author: Scott McMillan
 *  Created: 6 May 2002
 *  Summary: Dynamically scales to maintain a constant minimum pixel size
 *           beyond a certain range, and a constant maximum pixel size inside
 *           a certain range (the user only specifies the min and max sizes).
 *****************************************************************************/

#ifndef __SGL_UNSCALE_RANGE_HPP
#define __SGL_UNSCALE_RANGE_HPP

#include <sgl.h>
#include <sglGroup.hpp>

class SGL_DLL_API sglUnScaleRange : public sglGroup
{
public:
   sglUnScaleRange();

   virtual ~sglUnScaleRange();

   void setScaleParameters(float reference_size,
                           unsigned int min_pixel_size,
                           unsigned int max_pixel_size);

   unsigned int getMinPixelSize() const { return m_min_pixel_size; }

   unsigned int getMaxPixelSize() const { return m_max_pixel_size; }

   float getReferenceSize() const { return m_reference_size; }

   void setInverseMode(bool on) { m_inverse_mode = on; }

   bool getInverseMode() const { return m_inverse_mode; }

   // See sglNode::intersect(f) for details.
   virtual sglBound::IntersectResultEnum intersect(
      sglIntersectf &isector) const;

   // See sglNode::intersect(d) for details.
   virtual sglBound::IntersectResultEnum intersect(
      sglIntersectd &isector) const;

   // See sglNode::pick(f) for details.
   virtual void pick(sglPickf &pick_state, unsigned int cull_flags) const;

   // See sglNode::pick(d) for details.
   virtual void pick(sglPickd &pick_state, unsigned int cull_flags) const;

   // See sglNode::clone() for details.
   virtual sglNode *clone(unsigned int mode) const;

   // See sglObject::printInfo() for details.
   virtual void printInfo(ostream &ostrm, const char *indent_string) const;

protected:
   // See sglNode::cull(f) for details
   virtual void cull(sglCull<float> &trav_state,
                     unsigned int cull_flags) const;

   // See sglNode::cull(d) for details
   virtual void cull(sglCull<double> &trav_state,
                     unsigned int cull_flags) const;

   void copyTo(sglUnScaleRange *dst, unsigned int mode) const;

private:
   sglUnScaleRange(const sglUnScaleRange &);              // not implemented
   sglUnScaleRange &operator=(const sglUnScaleRange &);   // not implemented

   template <class T>
   T computeScale(sglProbeTemplate<T> &probe) const
        {
            T scale = (T)1;

            if (probe.getOrigViewFrustum().getOrthoFlag())
            {
                // HACK precompute this in sglProbeTemplate.
                scale =
                    probe.getOrigViewFrustum().getPlane(
                        sglFrustum<T>::eUP).getDistance() +
                    probe.getOrigViewFrustum().getPlane(
                        sglFrustum<T>::eDOWN).getDistance();
            }
            else
            {
                scale = -(probe.getModelViewMatrix())[3][2] *
                    tan((probe.getOrigViewFrustum().getFOVY())*0.5) * 2.0;
            }

            // do I need to check for zero scale?

            // compute size of reference size in pixels, the apparent size
            unsigned int viewport_x, viewport_y;
            probe.getViewportSize(viewport_x, viewport_y);
            T apparent_size = viewport_y*m_reference_size/scale;

            if (apparent_size < m_min_pixel_size && m_min_pixel_size != 0)
                scale = (T)m_min_pixel_size/apparent_size;
            else if (apparent_size > m_max_pixel_size && m_max_pixel_size != 0)
                scale = (T)m_max_pixel_size/apparent_size;
            else
                scale = (T)1;

            if (!m_inverse_mode)
                return scale;
            else
                return (T)1/scale;
        }

   template <class T>
   T computeScale(sglCull<T> &trav_state) const
        {
            T scale = 1.0f;

            if (trav_state.getOrigFrustum().getOrthoFlag())
            {
                // HACK precompute this in sglProbeTemplate.
                scale =
                    trav_state.getOrigFrustum().getPlane(
                        sglFrustum<T>::eUP).getDistance() +
                    trav_state.getOrigFrustum().getPlane(
                        sglFrustum<T>::eDOWN).getDistance();
            }
            else
            {
                scale = -(trav_state.getModelViewMatrix())[3][2] *
                    tan((trav_state.getOrigFrustum().getFOVY())*0.5) * 2.0;
            }

            // do I need to check for zero scale?

            // compute size of reference size in pixels, the apparent size
            unsigned int viewport_x, viewport_y;
            trav_state.getViewportSize(viewport_x, viewport_y);
            T apparent_size = viewport_y*m_reference_size/scale;

            if (apparent_size < m_min_pixel_size && m_min_pixel_size != 0)
                scale = (T)m_min_pixel_size/apparent_size;
            else if (apparent_size > m_max_pixel_size && m_max_pixel_size != 0)
                scale = (T)m_max_pixel_size/apparent_size;
            else
                scale = (T)1;

            if (!m_inverse_mode)
                return scale;
            else
                return (T)1/scale;
        }

private:
   float        m_reference_size;
   unsigned int m_min_pixel_size;
   unsigned int m_max_pixel_size;
   bool         m_inverse_mode;
};

#endif

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