Detailed Description

Geometric data cache.

The MVaryingParameter class provides a high-level interface to hardware shader varying parameters. By defining your shader's varying data through this class, you allow Maya to handle the attributes, editing, serialisation, requirements setup, and cache management for you in a standard way that ensure you'll be able to leverage future performance and functionlity improvements.

At setup time (either initial load or when the effect/technique is changed), your shader simply creates the list of parameters it requires, specifying the name, type, semantic of the parameters. At render time, you can then use the parameters to directly access the appropriate buffers for that surface data.

If you include a custom Attribute Editor template for your shader node, you can include these surface parameters by calling the AEhwShaderTemplateParameters script function. The following sample code provides a basic template you can modify - however your AE template can use as much or as little of this as you like:

global int $yourShaderNameTemplateInitialised = 0;

global proc AEyourShaderNameTemplate ( string $node )
{
    global int $yourShaderNameTemplateInitialised;
    if( $yourShaderNameTemplateInitialised == 0)
    {
        source "AEhwShaderTemplate.mel";
        $yourShaderNameTemplateInitialised = 1;
    }

    AEhwShaderTemplateHeader( $node);

    // Insert custom attributes between the swatch and the parameters here

    AEhwShaderTemplateParameters( $node);

    // Insert custom attributes after the parameters here

    AEhwShaderTemplateFooter( $node);
}

Examples:: hlslShader.cpp, and hlslShader.h.

#include <MVaryingParameter.h>

List of all members.

Public Types
enum	MVaryingParameterType { kInvalidParameter = -1, kStructure = 0, kFloat }
	Parameter types. More...
enum	MVaryingParameterSemantic { kNoSemantic = 0, kPosition, kNormal, kTexCoord, kColor, kWeight, kTangent = kWeight + 2, kBinormal }
	Parameter semantics (i.e. what the parameter represents). More...
Public Member Functions
	MVaryingParameter ()
	Create an uninitialised (i.e.
	MVaryingParameter (const MString &name, MVaryingParameterType type, int minElements=1, int maxElements=1, MVaryingParameterSemantic semantic=kNoSemantic, bool invertTexCoords=false)
	Create a new varying parameter.
	~MVaryingParameter ()
	Class destructor.
const MVaryingParameter &	operator= (const MVaryingParameter &other)
	Assignment operator.
const MString &	name () const
	Get the name of this parameter.
MVaryingParameter::MVaryingParameterType	type () const
	Get the type of this parameter.
MVaryingParameter::MVaryingParameterSemantic	semantic () const
	Get the semantic of this parameter.
MStatus	getBuffer (MGeometry &geometry, const void *&data, unsigned int &elements, unsigned int &count) const
	Get the data for this parameter as a system memory buffer.
MVaryingParameter::MVaryingParameterSemantic	getSourceType () const
	Get the type of data (e.g.
MString	getSourceSetName () const
	If the current data type supports data sets (e.g.
MStatus	setSource (MVaryingParameter::MVaryingParameterSemantic type, const MString &setName)
	While the source of geometry parameters is usually configured by the artist through Maya's user interface, this method allows you to programatically set the source of a geometry parameter, including both the data type (e.g.
unsigned int	getElementSize () const
	Get the size in bytes of one element of this parameter.
unsigned int	getMaximumStride () const
	Get the maximum stride of this parameter in bytes.
MStatus	addElement (const MVaryingParameter &child)
	Add a child element to this parameter.
unsigned int	numElements () const
	Get the number of elements in this structure.
MVaryingParameter	getElement (unsigned int i) const
	Get an element within a structure.
MStatus	removeElements ()
	Remove all child elements from a structure.
Friends
class	MVaryingParameterList Search for all occurrences

kInvalidParameter	Search for all occurrences
kStructure	Search for all occurrences
kFloat	Search for all occurrences

kNoSemantic	Search for all occurrences
kPosition	Search for all occurrences
kNormal	Search for all occurrences
kTexCoord	Search for all occurrences
kColor	Search for all occurrences
kWeight	Search for all occurrences
kTangent	Search for all occurrences
kBinormal	Search for all occurrences

MVaryingParameter	(	const MString &	name,
		MVaryingParameterType	type,
		int	minElements = `1`,
		int	maxElements = `1`,
		MVaryingParameterSemantic	semantic = `kNoSemantic`,
		bool	invertTexCoords = `false`
	)

[in]	name	the name of the new parameter. For independently configurable inputs, this must be unique across all parameters on the shader. If multiple parameters share the same name, only a single input will be presented to the user, and the value used to populate the set of commonly named parameters.
[in]	type	the type of the new parameter. This can either be an atomic type (e.g. float), or a structure containing other parameters. Vectors of atomic types (e.g. float4) are defined by setting the atomic type to kFloat, and specifying the maxElements value of 4.
[in]	minElements	specifies the minimum number of elements of the specified atomic type that should be used to populate this parameter. Many hardware channels allow binding of a variable number of elements per value; for example you can bind a stream of float3s or float4s to a color register. In this case, you would specify a minElements value of 3, and a maxElements value of 4. This value is ignored for structures and elements inside structures (elements inside a structure are always maxElements size).
[in]	maxElements	specifies the maximum number of elements of the specified atomic type that should be used to populate this parameter. See minElements for more information. This value is ignored for structures.
[in]	semantic	specifies the expected usage of the paramter (e.g. we expect this to be a colour, or a tangent, etc). This gives Maya a hint as to how the input should be presented to the user, and possibly even which input data is valid for this parameter. This value is ignored for structures.
[in]	invertTexCoords	If true the V texture coordinate will be inverted, so that it begins at the top of the texture rather than the bottom.

MStatus getBuffer	(	MGeometry &	geometry,
		const void *&	data,
		unsigned int &	elements,
		unsigned int &	count
	)		const

[in]	geometry	the geometry cache the data should be retrieved from. This corresponds to the shape (e.g. mesh) you want the data for.
[out]	data	returns a pointer to the data (or NULL if the parameter is not available).
[in]	elements	the number of elements specified for this parameter (e.g. is it 3 floats or 4 floats?)
[in]	count	the number of values returned for this parameter (e.g. there are 426 normals)

MStatus setSource	(	MVaryingParameter::MVaryingParameterSemantic	type,
		const MString &	setName
	)

[in]	type	the type of data to populate this parameter with
[in]	setName	the specific data set to use for parameter types which support data sets, such as UV and color.

MVaryingParameter Class Reference

OpenMayaRender - API module for rendering

Detailed Description

Public Types

Public Member Functions

Friends

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation