GLTransform.h

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//      File:           GLTransform.h
//      Author:         Changchang Wu
//      Description : GLTransform tookit for opengl display
//
//
//
//      Copyright (c) 2007 University of North Carolina at Chapel Hill
//      All Rights Reserved
//
//      Permission to use, copy, modify and distribute this software and its
//      documentation for educational, research and non-profit purposes, without
//      fee, and without a written agreement is hereby granted, provided that the
//      above copyright notice and the following paragraph appear in all copies.
//      
//      The University of North Carolina at Chapel Hill make no representations
//      about the suitability of this software for any purpose. It is provided
//      'as is' without express or implied warranty. 
//
//      Please send BUG REPORTS to ccwu@cs.unc.edu
//
#if !defined(GL_TRANSFORM_H)
#define GL_TRANSFORM_H

#include <math.h>
class GlTransform
{
public:
        double          cx, cy;
        double          q[4];
        double          t[3];
        double          sc, ds;
        GlTransform()
        {
                q[0]    =       1.0;
                q[1]    =       q[2]    =       q[3]    =0;
                t[0]    =       t[1]    =       t[2]    =0;
                sc              =       1.0;
                cx              =       cy              = 0;
        }
        void reset()
        {
                q[0]    =       1.0;
                q[1]    =       q[2]    =       q[3]    =0;
                t[0]    =       t[1]    =       t[2]    =0;
                sc              =       1.0;
        }
         void operator=(GlTransform& v)
         {
                q[0]    =       v.q[0];
                q[1]    =       v.q[1];
                q[2]    =       v.q[2];
                q[3]    =       v.q[3];
                t[0]    =       v.t[0];
                t[1]    =       v.t[1];
                t[2]    =       v.t[3];
                sc              =       v.sc;   
         }
         void operator *=(double scale)
         {
                sc      *=      scale;
                t[0]*=  scale;
                t[1]*=  scale;
                t[2]*=  scale;
         }
         void scaleset(double scale)
         {
                double ds = scale/sc;
                t[0]*=  ds;
                t[1]*=  ds;
                t[2]*=  ds;     
                sc  = scale;
         }
         void scaleup()
         {
                double scale;
                if(sc < 6) scale = float(int(sc))+1;
                else scale = sc * 2.0;
                scaleset(scale);
         }
         void scaledown()
         {
                double scale;
                if(sc >1.0 &&sc < 2.0) scale = 1.0;
                else scale = sc*0.5;
                scaleset(scale);
         }
         void translate(int dx, int dy, int dz =0)
         {
                t[0]    +=      dx;
                t[1]    +=      dy;
                t[2]    +=      dz;
         }
         void setcenter(double x, double y)
         {
                cx = x;
                cy = y;
                t[0] = t[1] = t[2] = 0;
         }

         void transform(double es = 1.0)
         {
            double s = sc* es;
                glTranslated(cx*es, cy*es, 0.0);
                glTranslated(t[0] ,t[1] ,t[2]);
                glScaled(s,s,s);
                glTranslated(-cx, - cy, 0);
         }
};

#endif