class MPxHwShaderNode

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Inheritance:

MPxHwShaderNode < MPxNode

public members:

enum	Writeable kWriteNone kWriteVertexArray kWriteNormalArray kWriteColorArrays kWriteTexCoordArrays kWriteAll
enum	DirtyMask kDirtyNone kDirtyVertexArray kDirtyNormalArray kDirtyColorArrays kDirtyTexCoordArrays kDirtyAll
enum	TransparencyOptions kIsTransparent kNoTransparencyFrontBackCull kNoTransparencyPolygonSort
	MPxHwShaderNode ()
virtual	~MPxHwShaderNode ()
virtual MPxNode::Type	type () const
virtual MStatus	bind ( const MDrawRequest & request, M3dView & view )
virtual MStatus	unbind ( const MDrawRequest & request, M3dView & view )
virtual MStatus	geometry ( const MDrawRequest & request, M3dView & view, int prim, unsigned int writable, int indexCount, const unsigned int * indexArray, int vertexCount, const int * vertexIDs, const float * vertexArray, int normalCount, floatArrayPtr normalArrays, int colorCount, floatArrayPtr colorArrays, int texCoordCount, floatArrayPtr texCoordArrays)
virtual MStatus	glBind ( const MDagPath & shapePath )
virtual MStatus	glUnbind ( const MDagPath & shapePath )
virtual MStatus	glGeometry ( const MDagPath & shapePath, int glPrim, unsigned int writeMask, int indexCount, const unsigned int* indexArray, int vertexCount, const int * vertexIDs, const float * vertexArray, int normalCount, floatArrayPtr normalArrays, int colorCount, floatArrayPtr colorArrays, int texCoordCount, floatArrayPtr texCoordArrays)
virtual bool	supportsBatching () const
virtual bool	invertTexCoords () const
const MDagPath &	currentPath () const
unsigned int	dirtyMask () const
virtual int	normalsPerVertex ()
virtual int	colorsPerVertex ()
virtual int	getColorSetNames ( MStringArray & names) NO SCRIPT SUPPORT
virtual int	texCoordsPerVertex ()
virtual int	getTexCoordSetNames ( MStringArray & names) NO SCRIPT SUPPORT
virtual bool	hasTransparency ()
virtual bool	provideVertexIDs ()
virtual unsigned int	transparencyOptions ()
virtual MStatus	getAvailableImages ( const MString & uvSetName, MStringArray & imageNames) NO SCRIPT SUPPORT
virtual MStatus	renderImage ( const MString & imageName, floatRegion region, int& imageWidth, int& imageHeight) NO SCRIPT SUPPORT
virtual MStatus	renderSwatchImage ( MImage & image )
static MPxHwShaderNode *	getHwShaderNodePtr ( MObject & object )
MObject	currentShadingEngine () const
static MObject	outColor output color value
static MObject	outColorR output color red
static MObject	outColorG output color green
static MObject	outColorB output color blue
static MObject	outTransparency output transparency value
static MObject	outTransparencyR output transparency red
static MObject	outTransparencyG output transparency green
static MObject	outTransparencyB output transparency blue
static MObject	outMatteOpacity output matte opacity value
static MObject	outMatteOpacityR output matte opacity red
static MObject	outMatteOpacityG output matte opacity green
static MObject	outMatteOpacityB output matte opacity blue
static MObject	outGlowColor output glow color value
static MObject	outGlowColorR output glow color red
static MObject	outGlowColorG output glow color green
static MObject	outGlowColorB output glow color blue

Inherited from MPxNode:

public members:

enum	Type kDependNode kLocatorNode kDeformerNode kManipContainer kSurfaceShape kFieldNode kEmitterNode kSpringNode kIkSolverNode kHardwareShader Custom shader derived from MPxHardwareShader kHwShaderNode Custom shader derived from MPxHwShaderNode kTransformNode kObjectSet kFluidEmitterNode kImagePlaneNode kParticleAttributeMapperNode kConstraintNode kLast
virtual void	postConstructor ()
virtual MStatus	compute ( const MPlug & plug, MDataBlock & dataBlock )
virtual bool	getInternalValueInContext ( const MPlug & plug, MDataHandle & dataHandle, MDGContext & ctx)
virtual bool	setInternalValueInContext ( const MPlug & plug, const MDataHandle & dataHandle, MDGContext & ctx)
virtual bool	getInternalValue ( const MPlug & plug, MDataHandle & dataHandle)
virtual bool	setInternalValue ( const MPlug & plug, const MDataHandle & dataHandle)
virtual int	internalArrayCount ( const MPlug & plug, const MDGContext & ctx) const
virtual void	copyInternalData ( MPxNode * )
virtual MStatus	legalConnection ( const MPlug & plug, const MPlug & otherPlug, bool asSrc, bool& isLegal ) const
virtual MStatus	legalDisconnection ( const MPlug & plug, const MPlug & otherPlug, bool asSrc, bool& isLegal ) const
virtual MStatus	setDependentsDirty ( const MPlug & plug, MPlugArray & plugArray)
virtual MStatus	connectionMade ( const MPlug & plug, const MPlug & otherPlug, bool asSrc )
virtual MStatus	connectionBroken ( const MPlug & plug, const MPlug & otherPlug, bool asSrc )
virtual bool	isPassiveOutput ( const MPlug & plug ) const
virtual MStatus	shouldSave ( const MPlug & plug, bool& isSaving )
virtual MPlug	passThroughToOne ( const MPlug & plug ) const
virtual bool	passThroughToMany ( const MPlug & plug, MPlugArray & plugArray ) const
MTypeId	typeId () const
MString	typeName () const
MString	name () const
virtual Type	type () const
virtual bool	isAbstractClass () const
MObject	thisMObject () const
static MStatus	addAttribute ( const MObject & attr )
static MStatus	inheritAttributesFrom ( const MString & parentClassName )
static MStatus	attributeAffects ( const MObject & whenChanges, const MObject & isAffected )
MStatus	setExistWithoutInConnections ( bool flag )
bool	existWithoutInConnections ( MStatus * ReturnStatus = NULL ) const
MStatus	setExistWithoutOutConnections ( bool flag )
bool	existWithoutOutConnections ( MStatus * ReturnStatus = NULL ) const
static MObject	message
static MObject	isHistoricallyInteresting
static MObject	caching
static MObject	state

protected members:

MDataBlock	forceCache ( MDGContext & ctx= MDGContext::fsNormal )
void	setMPSafe ( bool flag )
MStatus	setDoNotWrite ( bool flag )
bool	doNotWrite ( MStatus *ReturnStatus = NULL ) const

Documentation

Description

MPxHwShaderNode allows the creation of user-defined hardware shaders. A hardware shader allows the plug-in writer to control the on-screen display of an object in Maya.

You must derive a hardware shader node from MPxHwShaderNode for it to have any affect on the on-screen display at all. In addition to their affect on the on-screen display of objects, hardware shaders function as surface shader nodes. This allows you to connect any shading network up to the hardware shader's outColor attribute to handle the shading during a software render.

To create a working hardware shader, derive from this class and override the bind(), unbind(), and geometry() methods. If your hardware shader uses texture coordinates from Maya, you also need to override either texCoordsPerVertex or getTexCoordSetNames(). The other methods of the parent class MPxNode may also be overridden to perform dependency node capabilities.

NOTE: Plug-in hardware shaders are fully supported for polygonal mesh shapes. NURBS surfaces are only supported in the High Quality Interactive viewport and Hardware Renderer if the glBind/glGeometry/glUnbind methods of this class are implemented.

Functions

MPxHwShaderNode:: MPxHwShaderNode ()

Constructor

Class constructor.

MPxHwShaderNode:: ~MPxHwShaderNode ()

Destructor

Class destructor.

MPxNode::Type MPxHwShaderNode:: type () const

Description

This method returns the type of the node. This method should not be overridden by the user. It will return MPxNode::kHwShaderNode.

Return Value

• the type of node

MStatus MPxHwShaderNode:: bind (const MDrawRequest & request, M3dView & view)

Description

This method is invoked for hardware rendering to Maya's 3D view.

This is the preferred method of interactive feedback and performance. the "gl" version should be used for batch hardware rendering.

This method is called to set up the OpenGL state. It would typically ensure that textures were bound and that any specific OpenGL extensions are enabled. A status code of MS::kSuccess should be returned unless there was a problem during the display, such as insufficient memory or required input data is missing or invalid.

Arguments

• request the draw request.
• view the view in which to draw.

Return Value

• status code

Status Codes

• MS::kSuccess The method was successful.
• MS::kFailure An error has occurred.

MStatus MPxHwShaderNode:: unbind (const MDrawRequest & request, M3dView & view)

Description

This method is invoked for hardware rendering to Maya's 3D view.

This is the preferred method of interactive feedback and performance. the "gl" version should be used for batch hardware rendering.

This method is called to restore the OpenGL state. Specifically, it must disable any OpenGL extensions that the matching bind() method may have enabled. This is necessary to ensure that the rest of Maya's drawing code continues to work correctly. A status code of MS::kSuccess should be returned unless there was a problem such as insufficient memory or required input data is missing or invalid.

The arguments passed to this method are the same ones that were passed to the bind() method.

Arguments

• request the draw request.
• view the view in which to draw.

Return Value

• status code

Status Codes

• MS::kSuccess The method was successful.
• MS::kFailure An error has occurred.

MStatus MPxHwShaderNode:: geometry ( const MDrawRequest & request, M3dView & view, int prim, unsigned int writable, int indexCount, const unsigned int * indexArray, int vertexCount, const int * vertexIDs, const float* vertexArray, int normalCount, floatArrayPtr normalArrays, int colorCount, floatArrayPtr colorArrays, int texCoordCount, floatArrayPtr texCoordArrays)

Description

This method is invoked for hardware rendering to Maya's 3D view.

This is the preferred method of interactive feedback and performance. the "gl" version should be used for batch hardware rendering.

This method does all the actual OpenGL drawing. The arguments contain all the data to successfully call glDrawElements or glDrawRangeElements. It is possible that there will be multiple calls to this method surrounded by a single call to bind() and unbind().

Note 1. The array of vertex IDs returned corresponds to each triangle's vertex. This allows access to associated blind data per vertex. The vertexIDs array allows querying of information such as color per vertex etc.

Note 2. The array of array parameters passed to this method can contain sparse information. Check array positions against NULL to ensure that the array information item is valid.

It is necessary to use the indexArray to access information contained in the data arrays.

Arguments

• request the draw request.
• view the view in which to draw.
• prim the type of primitive to draw. This is one of the values accepted by glBegin(). Typically it will be GL_TRIANGLES but it could be any of the others.
• writable this is a mask which indicates which of the various array arguments can be modified in place. If a bit in writable is set then you can modify corresponding data array (after casting it to a non-const type). If the bit is not set in writable then you must not modify the data since it points to internal Maya storage. You can test the bits in writeable against the values defined by the enum MPxHwShaderNode::Writable.
• indexCount specifies both the number of indices to draw and the size of the indexArray argument.
• indexArray the array of index values. This array is in a format suitable for passing as the indices argument to glDrawElements() or glDrawRangeElements(). See the OpenGL documentation for details on calling these routines.
• vertexCount the number of elements in the vertexArray, the normalArray, each of the colorArrays, and each of the texCoordArrays.
• vertexIDs the component IDs of the vertices in vertexArray. This array is only provided if it was requested by overriding the provideVertexIDs() method to return true.
• vertexArray the array of vertex data. Currently, this is always 3 element floating point values. This data is in a format suitable for passing to glVertexPointer(). See the OpenGL documentation for details.
• normalCount the number of individual "normal" arrays that are being provided in normalArrays. See the description of normalsPerVertex method below for details.
• normalArrays the normal (and tangent) data suitable. There may be 0, 1, 2, or 3 "normal" arrays. See the description of the normalsPerVertex method below for details.
• colorCount the number of individual color arrays.
• colorArrays the arrays of color data. The first set of color data is pointed to by colorArrays[0]. Each color array contains vertexCount color values, each of which is 4 floating point values long and represents the red, green, blue, and alph values on a 0 to 1 scale. Each individual array is suitable for passing to glColorPointer().
• texCoordCount the number of texture coordinate arrays. Each array contains one set of UV texture coordinates.
• texCoordArrays the arrays of texture coordinate data. The first set of texture coordinate data is pointed to by texCoordArrays[0]. Each array contains vertexCount coordinate values, each of which is 2 floating point values long. Each individual array is suitable for passing to glTexCoordPointer().

Return Value

• status code

Status Codes

• MS::kSuccess The method was successful.
• MS::kFailure An error has occurred.

MStatus MPxHwShaderNode:: glBind (const MDagPath &)

Description

This method should only be overridden for hardware rendering.

The implementation can assume the graphics context and model view projection matrix have already been set.

This method will be invoked once per frame and should be overridden to allocate any resources needed for the draw. For example, binding vertex programs, fragment programs, or allocating textures. A status code of MS::kSuccess should be returned unless there was a problem such as insufficient memory or required input data is missing or invalid.

Arguments

• shapePath Path to the surface being drawn.

Return Value

• status code

Status Codes

• MS::kSuccess The method was successful.
• MS::kFailure An error has occurred.

MStatus MPxHwShaderNode:: glUnbind (const MDagPath &)

Description

This method should only be overridden for hardware rendering.

The implementation can assume the graphics context and model view projection matrix have already been set.

This method will be invoked once per frame and should be overridden to deallocate any resources used to draw. It's important that all resources be released when a batch hardware render has occured because the graphics context will be deleted. It may be desireable to override the other version of bind/unbind to keep track of whether the draw is for the 3D view or the batch hardware renderer. This information could then be used to better track the reuse of resources and optimize performance.

A status code of MS::kSuccess should be returned unless there was a problem.

Arguments

• shapePath Path to the surface being drawn.

Return Value

• status code

Status Codes

• MS::kSuccess The method was successful.
• MS::kFailure An error has occurred.

MStatus MPxHwShaderNode:: glGeometry ( const MDagPath & shapePath, int prim, unsigned int writable, int indexCount, const unsigned int * indexArray, int vertexCount, const int * vertexIDs, const float* vertexArray, int normalCount, floatArrayPtr normalArrays, int colorCount, floatArrayPtr colorArrays, int texCoordCount, floatArrayPtr texCoordArrays)

Description

This method should only be overridden for hardware rendering.

The implementation can assume graphics context and model view projection matrix have already been set.

This method does all the actual OpenGL drawing. The arguments contain all the data to successfully call glDrawElements or glDrawRangeElements. It is possible that there will be multiple calls to this method surrounded by a single call to bind() and unbind().

Note 1. The array of vertex IDs returned corresponds to each triangle's vertex. This allows access to associated blind data per vertex. The vertexIDs array allows querying of information such as color per vertex etc.

Note 2. The array of array parameters passed to this method can contain sparse information. Check array positions against NULL to ensure that the array information item is valid.

It is necessary to use the indexArray to access information contained in the data arrays.

Arguments

• shapePath Path to the surface being drawn.
• prim the type of GL primitive is supplied as it would be used for glBegin() or glDrawElements(). Typically it will be GL_TRIANGLES or GL_TRIANGLE_STRIP for drawing polygonal or nurb surfaces respectively.
• writable this is a mask which indicates which of the various array arguments can be modified in place. If a bit in writable is set then you can modify corresponding data array (after casting it to a non-const type). If the bit is not set in writable then you must not modify the data since it points to internal Maya storage. You can test the bits in writeable against the values defined by the enum MPxHwShaderNode::Writable.
• indexCount specifies both the number of indices to draw and the size of the indexArray argument.
• indexArray the array of index values. This array is in a format suitable for passing as the indices argument to glDrawElements() or glDrawRangeElements(). See the OpenGL documentation for details on calling these routines.
• vertexCount the number of elements in the vertexArray, the normalArray, each of the colorArrays, and each of the texCoordArrays.
• vertexIDs the component IDs of the vertices in vertexArray. This array is only provided if it was requested by overriding the provideVertexIDs() method to return true.
• vertexArray the array of vertex data. Currently, this is always 3 element floating point values. This data is in a format suitable for passing to glVertexPointer(). See the OpenGL documentation for details.
• normalCount the number of individual "normal" arrays that are being provided in normalArrays. See the description of normalsPerVertex method below for details.
• normalArrays the normal (and tangent) data suitable. There may be 0, 1, 2, or 3 "normal" arrays. See the description of the normalsPerVertex method below for details.
• colorCount the number of individual color arrays.
• colorArrays the arrays of color data. The first set of color data is pointed to by colorArrays[0]. Each color array contains vertexCount color values, each of which is 4 floating point values long and represents the red, green, blue, and alpha values on a 0 to 1 scale. The 3D view and hardware renderer handle missing color data differently. The 3D view will create an array and pass black colors for each vertex, whereas the hardware renderer will supply a NULL pointer to indicate that color per-vertex data is unavailable.
• texCoordCount the number of texture coordinate arrays. Each array contains one set of UV texture coordinates.
• texCoordArrays the arrays of texture coordinate data. The first set of texture coordinate data is pointed to by texCoordArrays[0]. Each array contains vertexCount coordinate values, each of which is 2 floating point values long. Each individual array is suitable for passing to glTexCoordPointer(). The 3D view and hardware renderer handle missing texture coordinates differently. The 3D view will create an array of [0,0] texture coordinates for each vertex, whereas the hardware renderer will supply a NULL pointer to indicate that uv-set data is unavailable.

Return Value

• status code

Status Codes

• MS::kSuccess The method was successful.
• MS::kFailure An error has occurred.

bool MPxHwShaderNode:: supportsBatching () const

Description

Specifies whether or not this shader supports batched rendering of shapes.

In normal rendering, a shader is invoked using bind/geometry/unbind (or glBind/glGeometry/glUnbind) once for each shape being rendered. When a shader is used in batched rendering mode however, bind is called once, a series of geometry calls are made for each shape being rendered, followed by a single call to unbind (and similarly for glBind, glGeometry and glUnbind). As shader binding/unbinding can be expensive, batched rendering can significantly improve rendering performance. The more (particularly expensive) operations that can be moved out of the geometry/glGeometry methods the greater the performance improvement is. Ideally, only shape specific operations (such as binding geometry arrays and shape matrices) should be left in the geometry methods.

It is important to note that your shader can only use batched rendering mode if there is no shape (i.e. dag path) specific code in bind, glBind, unbind, or glUnbind. If any of these methods perform shape specific processing, this code must either be moved into geometry/glGeometry, or you must return false in this method to indicate batching should be disabled for this shader.

By default, this method will return false to ensure compatibility with existing shader code.

Return Value

• true if this shader supports batched rendering
• false otherwise

bool MPxHwShaderNode:: invertTexCoords () const

Description

Specifies whether this shader requires inverted texture coordinates. (i.e. where the top-left hand corner of UV space is (0,0) instead of the bottom-left corner).

By default, this method will return false to ensure compatibility with existing shader code.

Return Value

• true if inverted texture coordinates are required
• false otherwise

int MPxHwShaderNode:: normalsPerVertex ()

Description

Specifies how many normals per vertex the HW shader would like Maya to provide. This can range from 0 to 3. The first normal is the surface normal. The second "normal" is the primary tangent (generally the "u" direction). The third "normal" is the secondary tangent or the binormal (generally the "v" direction). Together, the normal, tangent and binormal form an orthogonal basis frequently named "tangent space basis".

The tangent and binormal vectors are guaranteed to be normalized and orthogonal to the surface normal. Please note that extracting the tangent and/or binormal requires expensive calculations, that will slow down refresh time substantially. In a future version, Maya may cache the resulting tangent space basis; in the meantime, only ask for more than one normal per vertex if they are absolutely required.

Also note that the tangent and binormal calculation requires a uv map. Currently, they are always computed from the first available uv map; if there is no uv mapping on the surface, Maya will only provide surface normals in the geometry call, regardless of the value returned by normalsPerVertex().

If you do not override this method, Maya will provide 1 normal per vertex.

Maya will automatically and silently clamp the result of this function to the [0,3] range.

COMPATIBILITY NOTE: Automatic tangent space basis calculation is only supported starting with Maya 4.0.1. Maya 4.0 supported a different scheme that was much more complicated and no longer supported.

Return Value

• the number of normal values desired. (0 = none, 1 = surface normal only, 2 = surface normal + tangent, 3 = surface normal + tangent + binormal)

int MPxHwShaderNode:: colorsPerVertex ()

Description

This method returns the number of color values per vertex that the hw shader node would like to receive from Maya. Maya will attempt to provide all the color data that the shader would like but it will never provide more data that is actually available in the shape. The color sets returned by getColorSetNames() will override the number of color sets specified by colorsPerVertex(). If you do not override this method or getColorSetNames(), Maya will provide no colors per vertex.

Return Value

• the number of color values desired

int MPxHwShaderNode:: getColorSetNames ( MStringArray & names)

Description

This method returns an array of color per vertex set names. Maya will attempt to provide color per vertex data from these maps in the corresponding array element in the colorArrays argument to the geometry method. For example, if the names[2] is "cpv56" then colorArrays[2] will be the array of values from cpv56, or NULL if the shape being rendered does not have a color set of that name. If this method is not overridden an empty list of names will be returned, and Maya will use colorsPerVertex() to determine how many color sets to provide.

Arguments

• names a string array holding the names of the color per vertex sets from which color data should be extracted.

Return Value

• the number of elements in the names array.

int MPxHwShaderNode:: texCoordsPerVertex ()

Description

This method returns the number of texture coordinate values per vertex that the hw shader node would like to receive from Maya. Maya will attempt to provide all the texture coordinate data that the shader would like but it will never provide more data than is actually available in the shape. The uv sets returned by getTexCoordSetNames() will override the number of uv sets specified by texCoordsPerVertex(). If you do not override this method or getTexCoordSetNames(), Maya will provide no texture coordinates per vertex.

NOTE: Currently, Maya only retains 2 dimensional texture coordinate data but this may change in a future release.

Return Value

• the number of texture coordinate values desired

int MPxHwShaderNode:: getTexCoordSetNames ( MStringArray & names)

Description

This method returns an array of texture coordinate set names. Maya will attempt to provide texture coordinates from these maps in the corresponding array element in the texCoordArrays argument to the geometry method. For example, if the names[2] is "uvSet3" then texCoordArrays[2] will be the array of values from uvSet3. If this method is not overridden an empty list of names will be returned, and Maya will use texCoordsPerVertex() to determine how many uv sets to provide.

Arguments

• names a string array holding the names of the uvSets from which texture coordinate data should be extracted.

Return Value

• the number of elements in the names array.

bool MPxHwShaderNode:: hasTransparency ()

Description

This method returns a boolean value that indicates whether the object will be drawn transparently or not. Transparent objects must be drawn after all the opaque objects in the scene or they will not display correctly. Maya uses the return value to determine when it can draw this shape.

Note : The functionality in this method has been subsumed by the transparencyOptions() method. It is recommended that shader node writers use this newer method as it provides greater control over how transparency is interpreted by Maya's refresh mechanism.

For backward compatibility, if this method is specified and returns a "true" value, it will override the transparencyOptions() method.

Return Value

• true if the object will be transparent or false if it will not.

unsigned int MPxHwShaderNode:: transparencyOptions ()

Description

This method returns transparency options for usage as hints for Maya's internal draw during a given rendering pass. Parameters are returned via an integer containing masked out bits. By default the mask is set to 0, meaning that the drawing should be treated as regular opaque object drawing. This will generally mean one call per draw pass.

Options to control transparency are specified by returning one or more masks specified by the TransparencyOptions enumeration :

• kIsTransparent : Draw as a transparent object. If no transparency overrides are specified, then control of how to draw during a given pass is determined internally by Maya's refresh algorithm, and options the user can set per modelling viewport.
• kNoTransparencyFrontBackCull : When kisTransparent is set and this flag is set, do not perform transparency drawing using the internal 2-pass front-face + back-face culling algorithm.
• kNoTransparencyPolygonSort : When kisTransparent is set and this flag is set, do not perform transparency drawing using the internal 2-pass drawing of back-to-front sorted triangles.

Note : Setting the "hasTransparency()" method to true will override this method. This is for backward compatibility with behaviour on existing hardware shader nodes. It is recommended that shaders use the "transparencyOptions()" override, and not longer use the older "hasTransparency()" override from their shader classes.

Return Value

• integer containing the appropriate options set via masks.

bool MPxHwShaderNode:: provideVertexIDs ()

Description

This method returns a boolean value that indicates whether a map of the vertex IDs will be provided to the geometry method.

Return Value

• true if vertex IDs should be provided to the geometry method.

MStatus MPxHwShaderNode:: getAvailableImages ( const MString & uvSetName, MStringArray & imageNames)

Description

This method allows your shader to define the list of images which are available in the UV texture editor for the UV set specified. Typically, this list will include one entry for each texture using the specified UV set, however, your shader is free to return as many images as you wish (for example, blending between two textures, texture alpha masks, artificially shaded views of bump/normal maps, etc). Your shader's renderImage method will be used to render the images themselves.

Arguments

• uvSetName a string specifying the name of a UV set the channel list should be filtered against.

• imageNames a string array holding the names of the images this shader defines which are valid for the uvSetName specified.

Return Value

• status code

Status Codes

• MS::kSuccess The method was successful.
• MS::kFailure An error has occurred.
• MS::kNotImplemented Use the default behaviour.

MStatus MPxHwShaderNode:: renderImage ( const MString & imageName, floatRegion region, int& imageWidth, int& imageHeight)

Description

This method allows you to to render the background image used for this shader in the UV texture editor. The image requested will be one of the image names returned by your shader's getAvailableImages method.

The implementation can assume OpenGL context, model view projection matrix, and texture transformations have already been set. A default color of white will be set, however you are free to change this. The magnification filter will be set to either point or bilinear based on user configuration and should not be modified. The values of GL_TEXTURE_WRAP_S and GL_TEXTURE_WRAP_T are undefined on entry, and your implementation is responsible for setting them to appropriate values (e.g. GL_REPEAT).

The arguments contain the name of the image to render, and the vertex and texture coordinate values to use at each corner of the rectangular image being rendered. Your implementation is responsible for restoring the original the value of any OpenGL state that is modified.

For example:

		glPushAttrib( <GL bits your shader modifies> );
		glPushClientAttrib( GL_CLIENT_VERTEX_ARRAY_BIT);

		... setup material here ...

		glBegin( GL_QUADS);
		glTexCoord2f(region[0][0], region[0][1]);
		glVertex2f(region[0][0], region[0][1]);
		glTexCoord2f(region[0][0], region[1][1]);
		glVertex2f(region[0][0], region[1][1]);
		glTexCoord2f(region[1][0], region[1][1]);
		glVertex2f(region[1][0], region[1][1]);
		glTexCoord2f(region[1][0], region[0][1]);
		glVertex2f(region[1][0], region[0][1]);
		glEnd();

		glPopAttrib();
		glPopClientAttrib();

   

Arguments

• imageName the name of the image to render. This corresponds to one of the image names returned by your shader's getAvailableImages method.
• region the rectangular region that should be rendered. The values of this parameter should be used to populate the vertex and texture coordinates of the rectangle being rendered.
• imageWidth if applicable, this argument should be set to the image's native width (e.g. texture pixel width).
• imageHeight if applicable, this argument should be set to the image's native height (e.g. texture pixel height).

Return Value

• status code

Status Codes

• MS::kSuccess The method was successful.
• MS::kFailure An error has occurred.

MStatus MPxHwShaderNode:: renderSwatchImage ( MImage & image )

Description

If the shader specifies to override swatch rendering, then this method must be overridden in order to draw anything into a swatch. The default implementation is to draw nothing. The basic logic to draw a swatch is as follows:

• Determine the size of the swatch required. This is the dimensions of the MImage passed in as an argument. The pixels for the MImage will have been pre-allocated. The format of the pixels is 32-bit R,G,B,A, with 8-bits per channel.
• Either use an offscreen "swatch context" provided to you or use your own offscreen context. The provided context is available via the MHardwareRenderer class method makeSwatchContextCurrent(). Note that the swatch context may be smaller than the desired image size. In this case the rendering dimensions will be clamped.
• Either use swatch geometry provided to you, or use your own swatch geometry. The provided geometry is available via the method MHardwareRenderer::referenceDefaultGeometry(). The possible "default" geometries are either a sphere, cube or plane.
• Either use the provided "default" light and "default" camera or set up your own. Use the methods (getSwatchOrthoCameraSetting(), getSwatchLightDirection()) on MHardwareRenderer to get these defaults.
• Read back the swatch context into the provided MImage. The convenience method MHardwareRenderer::readSwatchContextPixels() can be used. By default the format of the MImage and the swatch context are the same, so the user does not need to worry about this. The context will read into the pre-allocated MImage pixels.
• Unreference any swatch geometry used for rendering using MHardwareRenderer::dereferenceGeometry().

Arguments

• image The image which contain the pixels of the rendered swatch.

Return Value

• status code

Status Codes

• MS::kNotImplemented : No rendering will occur.

MPxHwShaderNode * MPxHwShaderNode:: getHwShaderNodePtr ( MObject & object )

Description

This is a static convenience method to be able to get an MPxHwShaderNode from an MObject provided by a swatch generator class (Class derived from MSwatchRenderRegister).

Arguments

• MObject The object to examine.

Return Value

• A pointer to an MPxHwShaderNode. If the method failed for any reason then a 0 (null) will be returned.

const MDagPath & MPxHwShaderNode:: currentPath () const

Description

This method returns a reference to the current path that the shader is invoked for.

The path is only valid before a call to any of the attribute specifying routines:

• normalsPerVertex()
• colorsPerVertex()
• getColorSetNames()
• texCoordsPerVertex()
• getTexCoordSetNames()
• hasTransparency()
• provideVertexIDs()

The path is not guaranteed to be valid at any other time.

This method allows the plugin to return attribute queries which are relative to a specific path or object.

For example, the plugin can retrieve the MObject from the path, then use the MFnMesh class on the MObject, assuming the object is a polygonal surface. Through MFnMesh the code can query the actual number of texture coordinate sets on the surface and return appropriate values for the getTexCoordSetNames() routine.

The [gl]bind(), [gl]unbind() and [gl]geometry() routines already have access to a dag path which is the same path as the one which can be retrieved via this method.

For performance reasons, it is recommended that for those methods the MDagPath passed in as an argument should be used.

Return Value

• An MDagPath. Note that this path can be invalid Use MDagPath::isValid() to confirm the validity of the path.

unsigned int MPxHwShaderNode:: dirtyMask () const

Description

This method returns a "dirty" mask that indicates which geometry items have changed from the last invocation of the plugin to draw. The mask is valid at the time that geometry() or glGeometry() is called and at no other time.

Note that this mask is relative to the geometry for the current object (path) being drawn by the shader. The current path is the MDagPath argument passed in via the geometry routines.

In general the mask will mark the geometry as not being dirty.

Scenarios where the geometry will be marked dirty include:

• Whenever a geometry attribute changes. For example positions or normals are modified.
• Whenever the attributes being requested changes from the previous invocation of the shader. For example, if in the previous invocation the plugin asks for position only, and in the current invocation asks for position and normals, then the geometry attributes returned will have changed and thus be marked "dirty".

Return Value

• The dirty mask which can be bit 'AND'ed against the MPxHwShaderNode::DirtyMask enum.

MObject MPxHwShaderNode:: currentShadingEngine () const

Description

This method returns an MObject to the shading engine that is currently being rendered. This method will only return a valid MObject during the following calls:

• normalsPerVertex()
• colorsPerVertex()
• getColorSetNames()
• texCoordsPerVertex()
• getTexCoordSetNames()
• hasTransparency()
• provideVertexIDs()
• getAvailableImages()
• bind(), glBind()
• geometry(), glGeometry()
• unbind(), glUnbind()

Return Value

• The shading engine currently being rendered.

This class has no child classes.