DisplayListObject.cpp

Demonstration of a 3D render object that uses display lists to cache its result. Note that with the next big release of OpenGL display lists won't be supported anymore. Thus, it might be good to use vertexbuffers instead.

Start e.g.:

../../../bin/vish DisplayListObject.vis

See also:

Required tutorial: - Simple3DObject.cpp

Further tutorial: - VertexBufferObject.cpp - SimpleCoords.cpp - VectorFieldLines.cpp

#include <stdio.h>

#include <ocean/GLvish/VRenderObject.hpp>
#include <ocean/plankton/VCreator.hpp>
#include <ocean/plankton/VTime.hpp>
#include <ocean/GLvish/BoundingBox.hpp>

#include <stdio.h>

using namespace Wizt;


/*
 Render object.
 */
class   DisplayListObject : public VRenderObject
{
        struct  MyState : State
        {
                double  complexity;

                MyState()
                : complexity(0.5)
                {}
        };

        override RefPtr<State> newState() const
        {
                return new MyState();
        }

        virtual void render(VRenderContext&Context) const;

public:
        TypedSlot<double>       Complexity;

        DisplayListObject(const string&name, int p, const RefPtr<VCreationPreferences>&VP)
        : VRenderObject(name, p, VP)
        , Complexity(this, "complexity", 0.5)
        {}

        ~DisplayListObject()
        {}
};

void DisplayListObject::render(VRenderContext&Context) const
{
static  GLfloat Red[4]   = {0.9, 0.1, 0.1, 1.0 }; 

int     N = 300;
double  r = 1.0;

double  complexity = 0.5; 
        Complexity << Context >> complexity; 

double  dphi = 3.1415/ 10,
        zs   = 0.1 * complexity;


        glEnable( GL_COLOR_MATERIAL );
        glColorMaterial( GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE ); 

        // mark the beginning of an object that can be picked by the mouse
        SubObjectBegin(Context); 
        
        // define the highlight color of an picked object
        vglColor4fv(Context, Red, 0.4); 

        glEnable(GL_DEPTH_TEST); 

// create and save state of this object (created only when called the first time) 
RefPtr<MyState>  state = myState(Context);

// create and save ParameterSpace (created only when called the first time) 
RefPtr<ValueSet> RenderParameterSpace = new ValueSet(); 

// Test if a displaylist of given state of this object and parameterspace is already there. 
RefPtr<DisplayList> DL; 
        try
        {
                DL = Context(*state)(this)( RenderParameterSpace ); 
        } 
        catch(...)
        {}

        // If it is and if local parameter complexity has not changed from complexity saved in the state, just draw existing display list 
        if (DL && state->complexity == complexity)
        {
                if (DL->call() )
                        return; 
        } 

        // create displaylist for contex
        DL = Context[*state][this][ RenderParameterSpace ];
        if (!DL) throw "No Display List!?"; 

        // save local parameter complexity to complexity in the state
        state->complexity = complexity; 

        // reset BoundingBox
        resetBBox(Context); 

        // start displaylist, draw obeject
        glCompile( *DL )
        {
                glBegin( GL_QUAD_STRIP ); 
                for (int i=0;i<N;i++) 
                {
                double  phi0 = i*dphi,
                        phi1 = (i+1/complexity)*dphi; 

                point   A, B; 
                        A = r*cos(phi0), r*sin(phi0), phi0*zs; 
                        B = r*cos(phi0), r*sin(phi0), phi1*zs; 

                bivector N; 
                        N = cos(phi0), sin(phi0), 0; 

                        // Enlarge BouningBox on demand
                        embrace( Context, A ); 
                        embrace( Context, B ); 

                        glNormal( N ); 
                        glVertex( A ); 
                        glVertex( B );
                } 
                glEnd();
        } 

        // BoundingBox has to be closed after calls of embrace(), new BoundingSphere is calculated
        closeBBox(Context);
}

static Ref<VCreator<DisplayListObject> > MyCreator("Tutorial/DisplayListObject", 0);

/*
 This line needs to be contained in ONE source file of each
 VISH plugin module. It's not important which one.
 */
VISH_DEFAULT_INIT

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