Visualization Library 2.0.0-b3

A lightweight C++ OpenGL middleware for 2D/3D graphics

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Clipping Planes Tutorial

This tutorial shows how to use clipping, planes, how to animate them and how to use them with multipassing rendering.

[From App_ClipPlanes.cpp]

class App_ClipPlanes: public BaseDemo
{
public:
void initEvent()
{
vl::Log::notify(appletInfo());
// load model
vl::ref<vl::Geometry> model = vl::loadResource("/models/3ds/monkey.3ds")->get<vl::Geometry>(0);
model->computeNormals();
// install transform
mClipTr = new vl::Transform;
rendering()->as<vl::Rendering>()->transform()->addChild(mClipTr.get());
// to be used later
// demonstrates multipassing clipping
// setup clipping pass 1
clip1_sh->setRenderState( light.get(), 0 );
clip1_sh->enable(vl::EN_LIGHTING);
clip1_sh->gocMaterial()->setBackDiffuse(vl::yellow);
clip1_sh->gocLightModel()->setTwoSide(true);
// clipping plane 1 setup
clip1_sh->gocClipPlane(0)->setPlane( vl::Plane(0.2f, vl::vec3(0,+1,0)) );
clip1_sh->gocClipPlane(0)->bindTransform( mClipTr.get() );
// setup clipping pass 2
clip2_sh->setRenderState( light.get(), 0 );
clip2_sh->enable(vl::EN_LIGHTING);
clip2_sh->gocMaterial()->setBackDiffuse(vl::green);
clip2_sh->gocLightModel()->setTwoSide(true);
// clipping plane 2 setup
clip2_sh->gocClipPlane(0)->setPlane( vl::Plane(0.2f, vl::vec3(0,-1,0)) );
clip2_sh->gocClipPlane(0)->bindTransform( mClipTr.get() );
// install the two passes for LOD 0
clip_fx->setLOD(0, clip1_sh.get(), clip2_sh.get());
// add model to the scene
sceneManager()->tree()->addActor( model.get(), clip_fx.get(), NULL );
// renders a plane for visual feedback
// setup effect
plane_fx->setRenderRank(1); // draw after the clipped model
plane_fx->shader()->enable(vl::EN_BLEND);
plane_fx->shader()->gocLightModel()->setTwoSide(true);
plane_fx->shader()->gocColor()->setValue(vl::fvec4(1,0,0,0.3f)); // transparent red
// add plane actor
vl::ref<vl::Geometry> plane = vl::makeGrid( vl::vec3(0,0,0), 4,4, 2,2 );
sceneManager()->tree()->addActor( plane.get(), plane_fx.get(), mClipTr.get() );
}
virtual void updateScene()
{
// animate the clipping planes and the rendered plane
vl::real t = (vl::real)vl::Time::currentTime();
mClipTr->setLocalMatrix( vl::mat4::getRotation(t*90.0f, sin(t*(vl::fPi-3.0f)),1,cos(t)) );
}
protected:
};
// Have fun!