Developer Documentation
TrackballNode.cc
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45 
46 
47 //=============================================================================
48 //
49 // CLASS TrackballNode - IMPLEMENTATION
50 //
51 //=============================================================================
52 
53 
54 //== INCLUDES =================================================================
55 
56 
57 #include "TrackballNode.hh"
58 #include <ACG/GL/GLPrimitives.hh>
59 
60 
61 //== NAMESPACES ===============================================================
62 
63 
64 namespace ACG {
65 namespace SceneGraph {
66 
67 
68 //== IMPLEMENTATION ==========================================================
69 
70 
71 void
72 TrackballNode::draw(GLState& /* _state */ , const DrawModes::DrawMode& /* _drawMode */ )
73 {
74  // draw the track ball
75  if (drawTrackball_)
76  {
77  ACG::GLState::disable(GL_LIGHTING);
78  ACG::GLState::shadeModel( GL_FLAT );
79  glPushMatrix();
80  glTranslatef(center()[0], center()[1], center()[2]);
81  glScalef(radius_, radius_, radius_);
82 
83  GLint previous[2];
84  glGetIntegerv(GL_POLYGON_MODE,previous);
85  glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
86  ACG::GLSphere sphere(20, 20);
87  sphere.draw_primitive();
88  glPolygonMode(GL_FRONT,previous[0]);
89  glPolygonMode(GL_BACK,previous[1]);
90  glPopMatrix();
91  }
92 
93 
94  // draw the coord axes
95  if (drawAxes_)
96  {
97  // store original settings
98  GLfloat backupColor[4], backupLineWidth;
99  glGetFloatv(GL_CURRENT_COLOR, backupColor);
100  glGetFloatv(GL_LINE_WIDTH, &backupLineWidth);
101 
102  ACG::GLState::disable(GL_LIGHTING);
103  ACG::GLState::shadeModel( GL_FLAT );
104  glLineWidth(3.0);
105 
106  glColor3f(1.0, 0.0, 0.0);
107  glBegin(GL_LINES);
108  glVertex(center());
109  glVertex(center() + radius_*xAxis_);
110  glEnd();
111 
112  glColor3f(0.0, 1.0, 0.0);
113  glBegin(GL_LINES);
114  glVertex(center());
115  glVertex(center() + radius_*yAxis_);
116  glEnd();
117 
118  glColor3f(0.0, 0.0, 1.0);
119  glBegin(GL_LINES);
120  glVertex(center());
121  glVertex(center() + radius_*zAxis_);
122  glEnd();
123 
124  // restore original settings
125  glColor4fv(backupColor);
126  glLineWidth(backupLineWidth);
127  }
128 }
129 
130 
131 //----------------------------------------------------------------------------
132 
133 
134 void
135 TrackballNode::mouseEvent(GLState& _state, QMouseEvent* _event)
136 {
137  Vec3d oldPoint3D;
138  Vec2i newPoint2D(_event->pos().x(), _event->pos().y());
139  Vec3d newPoint3D;
140 
141 
142  switch (_event->type())
143  {
144  case QEvent::MouseButtonPress:
145  {
146  break;
147  }
148 
149 
150  case QEvent::MouseButtonDblClick:
151  {
152  if (mapToSphere(_state, oldPoint2D_, oldPoint3D))
153  {
154  // toggle drawTrackball_
155  if (_event->button() == Qt::LeftButton)
156  drawTrackball_ = !drawTrackball_;
157 
158  // toggle drawAxes_
159  if (_event->button() == Qt::MidButton)
160  drawAxes_ = !drawAxes_;
161  }
162  break;
163  }
164 
165 
166  case QEvent::MouseMove:
167  {
168  bool hit0 = mapToSphere(_state, newPoint2D, newPoint3D);
169  bool hit1 = mapToSphere(_state, oldPoint2D_, oldPoint3D);
170 
171  if (hit0 && hit1)
172  {
173 
174  // scaling
175  if ((_event->button() & Qt::LeftButton) &&
176  (_event->button() & Qt::MidButton))
177  {
178  double s = 1.0 + ((double) (newPoint2D[1] - oldPoint2D_[1]) /
179  (double) _state.viewport_height());
180  scale(s);
181  }
182 
183 
184  // translation
185  else if (_event->button() & Qt::MidButton)
186  {
187  double value_x = (radius_ * ((newPoint2D[0] - oldPoint2D_[0]))
188  * 2.0 / (double) _state.viewport_width());
189 
190  double value_y = (radius_ * ((newPoint2D[1] - oldPoint2D_[1]))
191  * 2.0 / (double) _state.viewport_height());
192 
193 
194  /* need inverse transposed matrix in order to
195  transform direction vectors */
197  m.transpose();
198 
199 
200  Vec3d dx, dy;
201 
202  // axis aligned
203  if (drawAxes_)
204  {
205  dx = m.transform_point(xAxis_);
206  dy = m.transform_point(yAxis_);
207  }
208 
209  // screen space translation
210  else
211  {
212  dx = m.transform_vector(_state.right());
213  dy = m.transform_vector(_state.up());
214  }
215 
216  dx.normalize();
217  dy.normalize();
218  translate(value_x*dx - value_y*dy);
219  }
220 
221 
222 
223  // rotation
224  else if (_event->button() & Qt::LeftButton)
225  {
226  Vec3d axis = oldPoint3D % newPoint3D;
227  double cos_angle = ( oldPoint3D | newPoint3D );
228 
229 
230  if (fabs(cos_angle) < 1.0)
231  {
232  // rotate coord axes
233  if (_event->modifiers() & Qt::AltModifier)
234  {
235  GLMatrixd mat;
236 
237  mat.identity();
238  mat.rotate(acos(cos_angle)*180.0/M_PI, axis);
239 
240  /* transform_point works since only
241  rotations and no translations are
242  involved */
243  xAxis_ = mat.transform_point(xAxis_);
244  yAxis_ = mat.transform_point(yAxis_);
245  zAxis_ = mat.transform_point(zAxis_);
246  }
247 
248  // normal rotation
249  else rotate(acos(cos_angle)*180.0/M_PI, axis);
250  }
251  }
252  }
253 
254 
255  break;
256  }
257 
258  default: // avoid warning
259  break;
260  }
261 
262 
263  // store 2D point
264  oldPoint2D_ = newPoint2D;
265 }
266 
267 
268 //----------------------------------------------------------------------------
269 
270 
271 bool
273  const Vec2i& _v2,
274  Vec3d& _v3 )
275 {
276  // Qt -> GL coordinate systems
277  unsigned int x = _v2[0];
278  unsigned int y = _state.context_height() - _v2[1];
279 
280 
281  // get ray from eye through pixel (trackball coords)
282  Vec3d origin, direction;
283  _state.viewing_ray(x, y, origin, direction);
284 
285 
286  // translate and scale trackball to unit sphere
287  origin -= center();
288  origin /= radius_;
289 
290 
291  // calc sphere-ray intersection
292  // (sphere is centered at origin, has radius 1)
293  double a = direction.sqrnorm(),
294  b = 2.0 * (origin | direction),
295  c = origin.sqrnorm() - 1.0,
296  d = b*b - 4.0*a*c,
297  t;
298 
299  if (d < 0.0) return false;
300  else if (d == 0.0) t = -b / (2.0*a);
301  else
302  {
303  // t1 = (-b - sqrt(d)) / (2.0*a), t2 = (-b + sqrt(d)) / (2.0*a)
304  a = 1.0 / (2.0*a);
305  d = sqrt(d);
306  double t1 = (-b - d) * a;
307  double t2 = (-b + d) * a;
308  t = (t1 < t2) ? t1 : t2;
309  }
310 
311  _v3 = origin + direction*t;
312 
313  return true;
314 }
315 
316 
317 //=============================================================================
318 } // namespace SceneGraph
319 } // namespace ACG
320 //=============================================================================
void rotate(Scalar angle, Scalar x, Scalar y, Scalar z, MultiplyFrom _mult_from=MULT_FROM_RIGHT)
void translate(const Vec3d &_v)
Add a translation to the current Transformation.
static void shadeModel(GLenum _mode)
replaces glShadeModel, supports locking
Definition: GLState.cc:1729
const Vec3d & center() const
get center
Vec3d up() const
get up-vector w.r.t. camera coordinates
Definition: GLState.cc:906
int viewport_width() const
get viewport width
Definition: GLState.hh:847
Namespace providing different geometric functions concerning angles.
void transpose()
transpose matrix
bool mapToSphere(GLState &_state, const Vec2i &_v2, Vec3d &_v3)
Map 2D-screen-coords to trackball.
void identity()
setup an identity matrix
virtual void mouseEvent(GLState &_state, QMouseEvent *_event) override
get mouse events
VectorT< T, 3 > transform_point(const VectorT< T, 3 > &_v) const
transform point (x&#39;,y&#39;,z&#39;,1) = M * (x,y,z,1)
const GLMatrixd & inverse_matrix() const
return inverse matrix
Vec3d right() const
get right-vector w.r.t. camera coordinates
Definition: GLState.cc:918
static void disable(GLenum _cap, bool _warnRemoved=true)
replaces glDisable, but supports locking
Definition: GLState.cc:1527
int viewport_height() const
get viewport height
Definition: GLState.hh:849
VectorT< T, 3 > transform_vector(const VectorT< T, 3 > &_v) const
transform vector (x&#39;,y&#39;,z&#39;,0) = A * (x,y,z,0)
void glVertex(const Vec2i &_v)
Wrapper: glVertex for Vec2i.
Definition: gl.hh:95
void viewing_ray(int _x, int _y, Vec3d &_origin, Vec3d &_direction) const
Definition: GLState.cc:930
decltype(std::declval< S >() *std::declval< S >()) sqrnorm() const
compute squared euclidean norm
Definition: Vector11T.hh:421
int context_height() const
get gl context height
Definition: GLState.hh:855
void rotate(double _angle, const Vec3d &_axis)
void draw(GLState &_state, const DrawModes::DrawMode &_drawMode) override
Draw the trackball + axes (if enabled)
auto normalize() -> decltype(*this/=std::declval< VectorT< S, DIM >>().norm())
Definition: Vector11T.hh:453
const GLMatrixd & scale() const
return scale matrix