NAME

vzAppearance - Appearance description of a shape node.

INHERITS FROM

vzObject

HEADER FILE

#include <Volumizer2/Appearance.h>

PUBLIC METHOD SUMMARY

vzAppearance (

vzShader* shader);

void setParameter (

const char* name, vzParameter* parameter);

vzParameter* getParameter (

const char* name) const;

void setShader (

vzShader* shader);

vzShader* getShader (

) const;

vzParameter* getParameter (

int index) const;

const char* getParameterName (

int index) const;

int getNumParameters (

) const;

PROTECTED METHOD SUMMARY

virtual ~vzAppearance (

);

CLASS DESCRIPTION

The vzAppearance class describes how the shape should look when it is rendered. A vzShader must be specified, together with a set of shading parameters that affect the appearance. Each parameter associated with a vzAppearance has a name which is used by the vzShader to extract the corresponding values and take the appropriate actions. To get information about the specific shaders that are available for each render action, refer to the specific render action documentation: (e.g. vzTMRenderAction)

EXAMPLES

The following sample code shows how to use the vzAppearance class to describe the appearance of a vzShape. The following example initializes an appearance using the built-in shader vzTMLUTShader, which expects two parameters; One of type vzParameterVolumeTexture and name "volume" and two of type vzParameterLookupTable and name "lookup_table"

// Create the shader
vzShader *shader = new vzTMLUTShader();    

// Create the appearance
vzAppearance *appearance = new vzAppearance(shader); 

// Create the volume texture
vzParameterVolumeTexture *texture = myInitVolumeTexture(); 
 
// Create the lookup table
vzParameterLookupTable *table = myInitLookupTable();

// Set the respective parameters for the appearance
appearance->setParameter("volume", texture);
appearance->setParameter("lookup_table", table);

METHOD DESCRIPTIONS

   vzAppearance()

vzAppearance (

vzShader* shader);

Appearance constructor. The shader specifies the the volumetric shader to be used to render the shape. For example, vzTMLUTShader is a built-in shader which provides volume rendering of 3D textures using lookup tables. The shader is ref-counted by the appearance in the constructor.

Passing a NULL shader to the constructor will cause a vzError::error().

   ~vzAppearance()

virtual ~vzAppearance (

);

Appearance destructor. The shader and all the parameters for this appearance are unref'ed in the destructor.

   getNumParameters()

int getNumParameters (

) const;

Retrieve the number of parameters attached to the vzAppearance.

   getParameter()

vzParameter* getParameter (

const char* name) const;

Retrieve the parameter with name. If a parameter with name is not attached to the appearance, than a NULL is returned.

   getParameter()

vzParameter* getParameter (

int index) const;

Retrieve a parameter by its index in the list. The first element in the list is the 0th element. A NULL pointer is returned if index is not in the range [0 .. numParameters-1]. This method can be useful for iterating through the list of parameters. For example -

// Get the number of parameters -
int numParams = appearance->getNumParameters();

// Now iterate through the parameters
for(int i = 0; i < numParams; i++) {

    // Get the individual parameter by index
    vzParameter *param = appearance->getParameter(i);

    // Get the parameter's name 
    char *name = appearance->getParameterName(i);

    ........
}

   getParameterName()

const char* getParameterName (

int index) const;

Retrieve a parameter name by its index in the list. The first element in the list is the 0th element. A NULL pointer is returned if index is not in the range [0 .. numParameters-1].

   getShader()

vzShader* getShader (

) const;

Retrieve the shader attached to this appearance.

   setParameter()

void setParameter (

const char* name, vzParameter* parameter);

Adds the given parameter to the list of parameters for this appearance. The parameter will be ref counted by the class. If a parameter with the given name already exists, then its reference count will be decremented and it will be replaced by the new one.

   setShader()

void setShader (

vzShader* shader);

Sets the vzShader to be used with this appearance. The shader is ref-counted by the appearance and will be used for all future draw calls. Also, the initial shader's reference count will be decremented. The psuedocode for the method looks like -

void vzAppearance::setShader (vzShader *shader) {

  // Ref the new shader
  shader->ref();
  
  // unref the old shader
  currentShader->unref();

  // set the old shader to the new one
  currentShader = shader;
}

SEE ALSO

vzAppearance, vzObject, vzParameterLookupTable, vzParameterVolumeTexture, vzShader, vzShape, vzTMLUTShader, vzTMRenderAction

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