Geometry Primitives

Visualization Library includes a series of functions to create the most common primitive objects out of the box such as:

Box	Teapot	Capsule	Torus	Cylinder
UV Sphere	Icosphere	Icosahedron	Cone	Grid

The above primitive objects can be created by calling the following functions:

• vl::makeBox()
• vl::makeTeapot()
• vl::makeCapsule()
• vl::makeTorus()
• vl::makeCylinder()
• vl::makeUVSphere()
• vl::makeIcosphere()
• vl::makeIcosahedron()
• vl::makeCone()
• vl::makePyramid()
• vl::makeGrid()

The example below demonstrates how to create a simple applet that displays several geometrical primitives and allows the user to navigate through them by pressing the left/right arrow keys. Note how creating a geometrical primitive is just a matter of calling a function such as vl::makeBox(), vl::makeTeapot() etc.

[From App_Primitives.cpp]

class App_Primitives: public BaseDemo
{
public:
  void initEvent()
  {
    vl::Log::notify(appletInfo());

    const float objdim = 1;
    const float scene_radius = 4;

    /* solid fill shader */
    ref<Effect> fx = new Effect;
    fx->shader()->enable(EN_DEPTH_TEST);
    fx->shader()->enable(EN_LIGHTING);
    fx->shader()->setRenderState( new Light, 0 );
    fx->shader()->gocMaterial()->setDiffuse(vl::royalblue);

#if defined(VL_OPENGL)
    /* wireframe shader */
    fx->lod(0)->push_back( new Shader );
    fx->shader(0,1)->enable(EN_BLEND);
    fx->shader(0,1)->enable(EN_LINE_SMOOTH);
    fx->shader(0,1)->enable(EN_DEPTH_TEST);
    fx->shader(0,1)->enable(EN_POLYGON_OFFSET_LINE);
    fx->shader(0,1)->gocPolygonOffset()->set(-1.0f, -1.0f);
    fx->shader(0,1)->gocPolygonMode()->set(PM_LINE, PM_LINE);
    fx->shader(0,1)->gocColor()->setValue(vl::lightgreen);

    // speedup tricks:
    // we don't use lighting here so these won't be used, however including them in the second pass
    // will allow VL to avoid restoring and resetting them back and forth all the time.
    fx->shader(0,1)->setRenderState( fx->shader()->getMaterial() );
    fx->shader(0,1)->setRenderState( fx->shader()->getLight(0), 0 );
#endif

    /* create our primitives */
    mGeometries.push_back( vl::makeBox( vec3( 0, 0, 0 ), objdim*0.8f, objdim*0.8f, objdim*0.8f )  );
    mGeometries.push_back( vl::makeCone( vec3( 0, 0, 0 ), objdim, objdim, 20 )  );
    mGeometries.push_back( vl::makePyramid( vec3( 0, 0, 0 ), objdim, objdim )  );
    mGeometries.push_back( vl::makeIcosahedron( vec3( 0, 0, 0 ), objdim )  );
    mGeometries.push_back( vl::makeIcosphere( vec3( 0, 0, 0 ), objdim )  );
    mGeometries.push_back( vl::makeUVSphere( vec3( 0, 0, 0 ), objdim )  );
    mGeometries.push_back( vl::makeCylinder( vec3( 0, 0, 0 ), objdim, objdim, 20 )  );
    mGeometries.push_back( vl::makeTorus( vec3( 0, 0, 0 ), objdim*1.2f, 0.2f, 20, 40  )  );
    mGeometries.push_back( vl::makeCapsule( objdim/2.0f, objdim/2.0f, 20, CC_RoundedCap, CC_RoundedCap, vl::lightgreen, vl::lightgreen )  );
    mGeometries.push_back( vl::makeTeapot( vec3( 0, 0, 0 ), objdim*1.5f )  );
    mGeometries.push_back( vl::makeGrid( vec3( 0, 0, 0 ), objdim, objdim, 10, 10 )  );

    /* populate the scene */
    for(size_t i=0; i<mGeometries.size(); ++i)
    {
      /* arrange objects in a circle */
      ref<Transform> tr = new Transform;
      rendering()->as<Rendering>()->transform()->addChild( tr.get() );

      mat4 m = mat4::getRotation( 360 * i / (real)mGeometries.size(), 0, 1, 0) *
               mat4::getTranslation(0,0,-scene_radius);
      tr->setLocalMatrix( m );

      /* center the geometry */
      mGeometries[i]->computeBounds();
      m = mat4::getTranslation( -mGeometries[i]->boundingBox().center() );
      mGeometries[i]->transform( m );

      /* computes normals if not present */
      if (!mGeometries[i]->normalArray())
        mGeometries[i]->computeNormals();

      /* add object to the scene */
      sceneManager()->tree()->addActor( mGeometries[i].get(), fx.get(), tr.get() );
    }

    /* settings for the current visible object */
    mRot0  = 0;
    mRot1  = 0;
    mAngle = 360.0f / mGeometries.size();
  }

  /* press left/right arrow to rotate objects left/right */
  void keyPressEvent(unsigned short ch, vl::EKey key)
  {
    BaseDemo::keyPressEvent(ch, key);

    if ( !mTimer.isStarted() )
    {
      if (key == vl::Key_Left)
      {
        mTimer.start();
        mRot0 = mRot1;
        mRot1 = mRot1 + mAngle;
      }
      else
      if (key == vl::Key_Right)
      {
        mTimer.start();
        mRot0 = mRot1;
        mRot1 = mRot1 - mAngle;
      }
    }
  }

  /* animate rotation */
  void updateScene()
  {
    if ( mTimer.isStarted() )
    {
      float t = mTimer.elapsed();
      if (t>1)
      {
        t = 1;
        mTimer.stop();
      }
      t = smoothstep(0.0f, 1.0f, t);
      mat4 m = mat4::getRotation( mRot0*(1.0f-t) + mRot1*t, 0, 1, 0 );
      rendering()->as<Rendering>()->transform()->setLocalMatrix(m);
    }
  }

protected:
  std::vector< ref<Geometry> > mGeometries;
  Time mTimer;
  float mRot0;
  float mRot1;
  float mAngle;
};

// Have fun!