NAME

vzShapeSet - A set of volumetric shapes.

INHERITS FROM

vzObject

HEADER FILE

#include <Volumizer2/ShapeSet.h>

PUBLIC METHOD SUMMARY

   Creation/Modification

vzShapeSet (

);

static vzShapeSet* load (

const char* filename);

void add (

vzShape* shape);

void remove (

vzShape* shape);

void setGraphicsState (

vzGraphicsState* state);

   Get methods

int getNumShapes (

) const;

vzShape* get (

int i) const;

void getBoundingBox (

float bbox[6]) const;

vzGraphicsState* getGraphicsState (

) const;

   Utility methods

void sort (

int* indices) const;

static void setLoaderCB (

vzShapeSetLoaderCB loaderPtr);

PROTECTED METHOD SUMMARY

~vzShapeSet (

);

CLASS DESCRIPTION

vzShapeSet provides a simple abstraction for a collection of volumetric shapes (vzShape). Individual shapes can be added to and removed from the set. The class provides utility routines for computing the bounding box and visibility sorting of the set, among others. The ShapeSet provides a static load() method which uses the libvzxml loader library (based on Apache's Xerces library) to load and create a shape set.

METHOD DESCRIPTIONS

   vzShapeSet()

vzShapeSet (

);

Constructor for the shape set.

   ~vzShapeSet()

~vzShapeSet (

);

Destructor for the shape set.

   add()

void add (

vzShape* shape);

Add the shape to the shape set. The shape is added to the end of the set.

   get()

vzShape* get (

int i) const;

Get the i 'th shape from the set.

   getBoundingBox()

void getBoundingBox (

float bbox[6]) const;

Return the bounding box of the set of shapes.

   getGraphicsState()

vzGraphicsState* getGraphicsState (

) const;

Get the graphics state for the shape set.

   getNumShapes()

int getNumShapes (

) const;

Returns the number of shapes in the set

   load()

static vzShapeSet* load (

const char* filename);

Load a filename. For any plug-in modules, the plug-in DSO has to define the callback functions with the name createObjectClassName, where the ObjectClassName is the name of the class without the vz prefix.

// Type definition for the object loader callback
typedef vzObject * (*vzObjectLoaderCB)(const char *filename, 
                                       const char *userString);

// Example for loading class vzPolyGeometry
extern "C" vzObject *createPolyGeometry(const char *filename,
                                        const char *userString)
{
    vzPolyGeometry *geom = MyPolyLoader::load(filename);
    if(!geom) {
        fprintf(stderr,"Cannot load file %s using MyPolyLoader\n", filename);
        return NULL;
    }

return (vzObject *)geom;
}

   remove()

void remove (

vzShape* shape);

Remove the shape from the shape set.

   setGraphicsState()

void setGraphicsState (

vzGraphicsState* state);

Set the current graphics state to be used for controlling LOD parameters for this shape set. The graphics state would be used to update the center-of-interest of any clip-textures in the shape set. The application needs to update the graphics state depending on user interaction, etc. If the application does not use the above method to set a graphics state, the class would create a default one internally.

   setLoaderCB()

static void setLoaderCB (

vzShapeSetLoaderCB loaderPtr);

Set the loader method for this shape set. The loader method is defined as

typedef vzShapeSet * (*vzShapeSetLoaderCB)(const char *filename);

This callback is set by the libvzxml library automatically if the application links against the library or dlopen's the library. In this case, the shape set will be loaded using the XML based Volumizer loader. Applications can implement their own loaders for loading a vzShapeSet by setting the appropriate loader callback.

   sort()

void sort (

int* indices) const;

Sort the set of shapes in a back-to-front visibility sorted order. The sorted order is returned as the indices of the shapes in indices in a back-to-front sorted order. Note: The method does not allocate any memory for indices so the length of the array should atleast be equal to the value returned by getNumShapes(). The sort method assumes a valid OpenGL context and querries the OpenGL transformation matrices using the glGetDoublev calls.

Note on Sorting:The ShapeSet currently uses an approximate sorting algorithm which sorts the shapes by distance from the view point. This will not give accurate results if the shapes are of different sizes and/or if they are intersecting. If accurate sorting is critical, the application would need to implement its own sorting algorithm.

SEE ALSO

vzObject, vzShape, vzShapeSet

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