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#ifndef __GLGRAPHICS_SIMPLETRACKBALL_H__
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#define __GLGRAPHICS_SIMPLETRACKBALL_H__
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#include "CGLA/CGLA.h"
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#include "CGLA/Vec3f.h"
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namespace GLGraphics
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{
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/** \brief Simple trackball class.
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Use it to let the mouse movement control the viewing transformation.
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Typical usage:
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Construct the trackball as a global variable. Call the roll function
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from the GLUT mouse motion callback. Setup an idle callback which only
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calls glutPostRedisplay and call gl_view from the display function to
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set up the view transform.
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Deficiencies: This trackball has many shortcomings. For instance
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you cannot pan but only zoom and rotate. Go fix those problems!
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*/
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class SimpleTrackBall
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{
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CGLA::Vec3f center;
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float r; // Distance to center (origin)
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float theta; // Horizontal angle (azimuth)
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float phi; // vertical angle (zenith)
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float da; // angle increment
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float dr; // zoom increment
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bool firsttime; // used by the roll function
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float oldx, oldy;
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int X,Y,Z;
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void roll_x(float dx);
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void roll_y(float dy);
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public:
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/** Constructor. Call with the distance to the center. */
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SimpleTrackBall(const CGLA::Vec3f& _center, float _r):
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center(_center),
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r(_r), theta(static_cast<float>(M_PI_2)), phi(0.0f),
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da(static_cast<float>(M_PI/100.0)), dr(r/100.0f), firsttime(true),
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X(0), Y(1), Z(2)
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{}
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/** Callthis to set up OpenGL viewing matrix. It will also
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clear the view matrix. */
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void gl_view() const;
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void get_view(CGLA::Vec3f& c, CGLA::Vec3f& e, CGLA::Vec3f& u)
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{
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const CGLA::Vec3f up(0,1,0);
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float x = r * sin(theta) * cos(phi);
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float y = r * cos(theta);
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float z = r * sin(theta) * sin(phi);
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CGLA::Vec3f dir(x,y,z);
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CGLA::Vec3f eye = center + CGLA::Vec3f(dir[X], dir[Y], dir[Z]);
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c = center;
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e = eye;
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u = CGLA::Vec3f(up[X], up[Y], up[Z]);
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}
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void up_axis(char up);
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/** Move away. Typically called from the keyboard callback */
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void farther()
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{
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r += dr;
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}
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/** Move closer. Typically called from the keyboard callback */
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void closer()
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{
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r = CGLA::s_max(0.0f, r - dr);
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}
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/** Roll ball. Call with the x,y coordinates. This function is typically
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called from GLUT's mouse motion callback. */
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void roll(int x, int y);
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void set_center(const CGLA::Vec3f& _center)
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{
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center = _center;
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}
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};
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}
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#endif
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