Migrating viewer from 1.4 to 2.0

Table of Contents

• Introduction and features changes
• Converting code from QGLViewer to PolyscopeViewer
  • Example
• Feature losses

This part of the manual describes how to migrate from QGL viewer to Polyscope viewer

Author

Bastien Doignies

Introduction and features changes

With version 2.0 of DGtal, the internal and external structures of 3D visualization have been completely changed. The aim is to take advantage of the advanced features of Polyscope, a geometric object viewer.

The major changes are:

• No more QApplication class
• A simpler API with fewer classes
• More interaction with the simulation

Converting code from QGLViewer to PolyscopeViewer

The stream mechanism was kept, therefore, most draw commands remain the same. Here are the few steps to migrate from DGtal 1.4 to DGtal 2.0 are:

• Remove QApplication (and the .exec() file)
• Move the .show() method to the end of the block.
• CustomColor3D does not exist anymore. Instead use Display3D::drawColor (or Display3D::draw)
• UpdateDisplay is not needed anymore.
• SetMode3D does not exist anymore. Use Display3D::drawAsGrid, Display3D::drawAsPaving, Display3D::drawAsBalls, Display3D::drawAdjacencies instead.

Example

Old 1.4 code:

QApplication application(argc,argv); // To remove
 
typedef Viewer3D<> MyViewer;         // Change name
MyViewer viewer;                   
viewer.show();                       // To the end of the function
 
 
Point p1( -1, -1, -2 );
Point p2( 2, 2, 3 );
Domain domain( p1, p2 );
Point p3( 1, 1, 1 );
Point p4( 2, -1, 3 );
Point p5( -1, 2, 3 );
Point p6( 0, 0, 0 );
Point p0( 0, 2, 1 );
viewer <<  SetMode3D( p1.className(), "PavingWired" ); // viewer.drawAsPaving()
viewer << p1 << p2 << p3;
 
 
viewer <<  SetMode3D( p1.className(), "Grid" );                        // viewer.drawAsBalls()
viewer << CustomColors3D(Color(250, 0,0),Color(250, 0,0));             // viewer << Color(255, 0, 0);
viewer << p4 << p5 ; 
viewer <<  SetMode3D( p1.className(), "Both" );                        // Does not exist anymore
viewer << CustomColors3D(Color(250, 200,0, 100),Color(250, 0,0, 100)); // viewer << Color(250, 0, 0, 100);
viewer << p6;
viewer << CustomColors3D(Color(250, 200,0, 100),Color(250, 200,0, 20)); // viewer << Color(250, 200, 0, 20)
viewer << p0;
 
viewer << SetMode3D(domain.className(), "Paving"); // viewer.drawAsPaving();
viewer << domain;
viewer << MyViewer::updateDisplay; // To remove
 
return application.exec();         // To remove

New 2.0 code:

PolyscopeViewer viewer;                   
 
 
Point p1( -1, -1, -2 );
Point p2( 2, 2, 3 );
Domain domain( p1, p2 );
Point p3( 1, 1, 1 );
Point p4( 2, -1, 3 );
Point p5( -1, 2, 3 );
Point p6( 0, 0, 0 );
Point p0( 0, 2, 1 );
 
viewer.drawAsPaving();
viewer << p1 << p2 << p3;
 
viewer.drawAsGrid();
viewer << Color(250, 0,0) << p4 << p5; 
viewer << Color(250, 0, 0, 100)  << p6;
viewer << Color(250, 200, 0, 20) << p0;
 
viewer.drawAsPaving();
viewer << domain;
 
viewer.show();
return 0;         

Feature losses

As part of the simplification process, here are the old features that now have no direct equivalent:

• Most Draw Modes have been removed but can be emulated by manipulating the viewer interactively.
• Image and Domain transform no longer have dedicated classes. To rotate and translate them, use elements transform instead (DisplayData::transform).
• Mesh exports and exports.