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Constraints can limit the translation and/or rotation of a (Manipulated)Frame.
Try the different possible constraints using the T (translate) and R (rotate) keys. G and D change the constraint directions. Press Space to change the coordinate system (World, Camera or Local) which defines the constraint directions.
Press the Alt key while moving the mouse to move the camera.
#include "qglviewer.h" class Viewer : public QGLViewer { protected: void init(); void draw(); void help(); void keyPressEvent(QKeyEvent *); void displayText(); void displayType(const qglviewer::AxisPlaneConstraint::Type type, const int x, const int y, const char c); void displayDir(const unsigned short dir, const int x, const int y, const char c); private: unsigned short transDir; unsigned short rotDir; qglviewer::ManipulatedFrame* frame; void changeConstraint(); qglviewer::AxisPlaneConstraint* constraints[3]; unsigned short activeConstraint; };
#include "constrainedFrame.h" using namespace qglviewer; using namespace std; static AxisPlaneConstraint::Type nextConstraintType(const AxisPlaneConstraint::Type& type) { switch (type) { case AxisPlaneConstraint::FREE : return AxisPlaneConstraint::PLANE; break; case AxisPlaneConstraint::PLANE : return AxisPlaneConstraint::AXIS; break; case AxisPlaneConstraint::AXIS : return AxisPlaneConstraint::FORBIDDEN; break; case AxisPlaneConstraint::FORBIDDEN : return AxisPlaneConstraint::FREE; break; default : return AxisPlaneConstraint::FREE; } } void Viewer::changeConstraint() { unsigned short previous = activeConstraint; activeConstraint = (activeConstraint+1)%3; constraints[activeConstraint]->setTranslationConstraintType(constraints[previous]->translationConstraintType()); constraints[activeConstraint]->setTranslationConstraintDir (constraints[previous]->translationConstraintDir()); constraints[activeConstraint]->setRotationConstraintType (constraints[previous]->rotationConstraintType()); constraints[activeConstraint]->setRotationConstraintDir (constraints[previous]->rotationConstraintDir()); frame->setConstraint(constraints[activeConstraint]); } void Viewer::init() { constraints[0] = new LocalConstraint(); constraints[1] = new WorldConstraint(); constraints[2] = new CameraConstraint(camera); transDir = 0; // X direction rotDir = 0; // X direction activeConstraint = 0; frame = new ManipulatedFrame(); setManipulatedFrame(frame); frame->setConstraint(constraints[activeConstraint]); // The frames can be move without any key pressed setMouseStateKey(QGLViewer::FRAME, Qt::NoButton); // The camera can always be moved with the Alt key. setMouseStateKey(QGLViewer::CAMERA, Qt::AltButton); setDrawAxis(); help(); } void Viewer::draw() { glMultMatrixd(frame->matrix()); drawAxis(0.4); glScalef(0.3,0.3,0.3); const float nbSteps = 500.0; glBegin(GL_QUAD_STRIP); for (float i=0; i<nbSteps; ++i) { glColor3f((nbSteps-i)/nbSteps, .2 , i/nbSteps); float angle = i/20.0; float c = cos(angle); float s = sin(angle); float r1 = 1.0 - i/(1.3*nbSteps); float r2 = 0.8 - i/(1.3*nbSteps); float alt = i/nbSteps - 0.5; const float nor = .5; const float up = sqrt(1.0-nor*nor); glNormal3f(nor*c, up, nor*s); glVertex3f(r1*c, alt, r1*s); glVertex3f(r2*c, alt+0.05, r2*s); } glEnd(); displayText(); } void Viewer::keyPressEvent(QKeyEvent *e) { switch (e->key()) { case Qt::Key_G : transDir = (transDir+1)%3; break; case Qt::Key_D : rotDir = (rotDir+1)%3; break; case Qt::Key_Space: changeConstraint(); break; case Qt::Key_T : constraints[activeConstraint]->setTranslationConstraintType(nextConstraintType(constraints[activeConstraint]->translationConstraintType())); break; case Qt::Key_R : constraints[activeConstraint]->setRotationConstraintType(nextConstraintType(constraints[activeConstraint]->rotationConstraintType())); break; default: QGLViewer::keyPressEvent(e); } Vec dir(0.0,0.0,0.0); dir[transDir] = 1.0; constraints[activeConstraint]->setTranslationConstraintDir(dir); dir = Vec(0.0,0.0,0.0); dir[rotDir] = 1.0; constraints[activeConstraint]->setRotationConstraintDir(dir); updateGL(); } void Viewer::displayType(const AxisPlaneConstraint::Type type, const int x, const int y, const char c) { char text[12]; switch (type) { case AxisPlaneConstraint::FREE: sprintf(text, "FREE (%c)", c); break; case AxisPlaneConstraint::PLANE: sprintf(text, "PLANE (%c)", c); break; case AxisPlaneConstraint::AXIS: sprintf(text, "AXIS (%c)", c); break; case AxisPlaneConstraint::FORBIDDEN: sprintf(text, "FORBIDDEN (%c)", c); break; } drawText(x, y, text); } void Viewer::displayDir(const unsigned short dir, const int x, const int y, const char c) { char text[6]; switch (dir) { case 0: sprintf(text, "X (%c)", c); break; case 1: sprintf(text, "Y (%c)", c); break; case 2: sprintf(text, "Z (%c)", c); break; } drawText(x, y, text); } void Viewer::displayText() { drawText(10,height()-30, "TRANSLATION :"); displayDir(transDir, 190, height()-30, 'G'); displayType(constraints[activeConstraint]->translationConstraintType(), 10, height()-60, 'T'); drawText(width()-220,height()-30, "ROTATION"); displayDir(rotDir, width()-100, height()-30, 'D'); displayType(constraints[activeConstraint]->rotationConstraintType(), width()-220, height()-60, 'R'); switch (activeConstraint) { case 0 : drawText(20,20, "Constraint direction defined w/r to LOCAL (SPACE)"); break; case 1 : drawText(20,20, "Constraint direction defined w/r to WORLD (SPACE)"); break; case 2 : drawText(20,20, "Constraint direction defined w/r to CAMERA (SPACE)"); break; } } void Viewer::help() { cout << endl << "\t\t- - C o n s t r a i n e d F r a m e - -" << endl << endl; cout << "A manipulated frame can be constrained in its displacement." << endl; cout << "Try the different translation (press G and T) and rotation (D and R)" << endl; cout << "constraints while moving the frame with the mouse." << endl << endl; cout << "The constraints can be defined with respect to various coordinates" << endl; cout << "systems : press space to switch." << endl << endl; cout << "You can easily define your own constraints to create a specific frame behavior." << endl; }
#include "constrainedFrame.h" #include <qapplication.h> int main(int argc, char** argv) { // Read command lines arguments. QApplication application(argc,argv); // Instantiate the viewer. Viewer v; // Make the viewer window visible on screen. v.show(); // Set the viewer as the application main widget. application.setMainWidget(&v); // Run main loop. return application.exec(); }
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