MPxHwShaderNode Class Reference
[OpenMayaUI - API module for user interface, Proxy classes]

#include <MPxHwShaderNode.h>
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List of all members.

Detailed Description

Base class for user defined hardware shaders.

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.

Examples:

blindDataShader.h, cgfxShaderNode.h, GLSLShaderNode.h, hwAnisotropicShader_NV20.h, hwColorPerVertexShader.cpp, hwDecalBumpShader_NV20.h, hwManagedTextureShader.cpp, hwPhongShader.h, hwReflectBumpShader_NV20.h, hwRefractReflectShader_NV20.h, hwToonShader_NV20.h, hwUnlitShader.h, and pnTrianglesNode.h.


Public Types
enum   Writeable {
   kWriteNone = 0x0000, kWriteVertexArray = 0x0001, kWriteNormalArray = 0x0002, kWriteColorArrays = 0x0004,
   kWriteTexCoordArrays = 0x0008, kWriteAll = 0x000f
}
enum   DirtyMask {
   kDirtyNone = 0x0000, kDirtyVertexArray = 0x0001, kDirtyNormalArray = 0x0002, kDirtyColorArrays = 0x0004,
   kDirtyTexCoordArrays = 0x0008, kDirtyAll = 0x000f
}
enum   TransparencyOptions { kIsTransparent = 0x0001, kNoTransparencyFrontBackCull = 0x0002, kNoTransparencyPolygonSort = 0x0004 }
  Bit masks to be returned by the shader's transparencyOptions() method. More...

Public Member Functions
  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)
MObject  currentShadingEngine () const

Static Public Member Functions
static MPxHwShaderNode *  getHwShaderNodePtr (MObject &object)

Static Public Attributes
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

Member Enumeration Documentation

enum MPxHwShaderNode::Writeable

Bit masks used in conjuction with the 'writeable' parameter passed to the geometry() method to determine which arrays the shader is allowed to write to.

Enumerator:
kWriteNone   
kWriteVertexArray   
kWriteNormalArray   
kWriteColorArrays   
kWriteTexCoordArrays   
kWriteAll   

enum MPxHwShaderNode::DirtyMask

Bit masks used in combination with the return value of the dirtyMask() method to determine which portions of the geometry are dirty.

Enumerator:
kDirtyNone   
kDirtyVertexArray   
kDirtyNormalArray   
kDirtyColorArrays   
kDirtyTexCoordArrays   
kDirtyAll   

enum MPxHwShaderNode::TransparencyOptions

Bit masks to be returned by the shader's transparencyOptions() method.

Enumerator:
kIsTransparent  Draw as a transparent object. If this bit is not set then the others are ignored.
kNoTransparencyFrontBackCull  Do not use the two-pass front-and-back culling algorithm.
kNoTransparencyPolygonSort  Do not use two-pass drawing of back-to-front sorted polygons.

Constructor & Destructor Documentation

MPxHwShaderNode::MPxHwShaderNode (  ) 

Class constructor.

MPxHwShaderNode::~MPxHwShaderNode (  )  [virtual]

Class destructor.

Member Function Documentation

MPxNode::Type MPxHwShaderNode::type (  )  const [virtual]

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

Returns:
The type of node.

Reimplemented from MPxNode.

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

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.

Parameters:
[in]  request  the draw request.
[in]  view  the view in which to draw.
Returns:
Status code.
Status Codes:
Examples:
blindDataShader.h, hwAnisotropicShader_NV20.h, hwColorPerVertexShader.cpp, hwDecalBumpShader_NV20.h, hwPhongShader.h, hwReflectBumpShader_NV20.h, hwToonShader_NV20.h, hwUnlitShader.h, and pnTrianglesNode.h.

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

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.

Parameters:
[in]  request  the draw request.
[in]  view  the view in which to draw.
Returns:
Status code.
Status Codes:
Examples:
blindDataShader.h, hwAnisotropicShader_NV20.h, hwColorPerVertexShader.cpp, hwDecalBumpShader_NV20.h, hwPhongShader.h, hwReflectBumpShader_NV20.h, hwToonShader_NV20.h, hwUnlitShader.h, and pnTrianglesNode.h.

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  
) [virtual]

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.

Parameters:
[in]  request  the draw request.
[in]  view  the view in which to draw.
[in]  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.
[in]  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.
[in]  indexCount  specifies both the number of indices to draw and the size of the indexArray argument.
[in]  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.
[in]  vertexCount  the number of elements in the vertexArray, the normalArray, each of the colorArrays, and each of the texCoordArrays.
[in]  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.
[in]  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.
[in]  normalCount  the number of individual "normal" arrays that are being provided in normalArrays. See the description of normalsPerVertex method below for details.
[in]  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.
[in]  colorCount  the number of individual color arrays.
[in]  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().
[in]  texCoordCount  the number of texture coordinate arrays. Each array contains one set of UV texture coordinates.
[in]  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().
Returns:
Status code.
Status Codes:
Examples:
blindDataShader.h, hwAnisotropicShader_NV20.h, hwColorPerVertexShader.cpp, hwDecalBumpShader_NV20.h, hwPhongShader.h, hwReflectBumpShader_NV20.h, hwRefractReflectShader_NV20.h, hwToonShader_NV20.h, hwUnlitShader.h, and pnTrianglesNode.h.

MStatus MPxHwShaderNode::glBind ( const MDagPath &  shapePath  )  [virtual]

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.

Parameters:
[in]  shapePath  Path to the surface being drawn.
Returns:
Status code
Status Codes:
Examples:
cgfxShaderNode.h, GLSLShaderNode.h, hwColorPerVertexShader.cpp, hwManagedTextureShader.cpp, and hwPhongShader.h.

MStatus MPxHwShaderNode::glUnbind ( const MDagPath &  shapePath  )  [virtual]

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.

Parameters:
[in]  shapePath  Path to the surface being drawn.
Returns:
Status code
Status Codes:
Examples:
cgfxShaderNode.h, GLSLShaderNode.h, hwColorPerVertexShader.cpp, hwManagedTextureShader.cpp, and hwPhongShader.h.

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  
) [virtual]

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.

Parameters:
[in]  shapePath  Path to the surface being drawn.
[in]  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.
[in]  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.
[in]  indexCount  specifies both the number of indices to draw and the size of the indexArray argument.
[in]  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.
[in]  vertexCount  the number of elements in the vertexArray, the normalArray, each of the colorArrays, and each of the texCoordArrays.
[in]  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.
[in]  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.
[in]  normalCount  the number of individual "normal" arrays that are being provided in normalArrays. See the description of normalsPerVertex method below for details.
[in]  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.
[in]  colorCount  the number of individual color arrays.
[in]  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.
[in]  texCoordCount  the number of texture coordinate arrays. Each array contains one set of UV texture coordinates.
[in]  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.
Returns:
Status code
Status Codes:
Examples:
cgfxShaderNode.h, GLSLShaderNode.h, hwColorPerVertexShader.cpp, hwManagedTextureShader.cpp, and hwPhongShader.h.

bool MPxHwShaderNode::supportsBatching (  )  const [virtual]

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.

Returns:
true if this shader supports batched rendering, false otherwise
Examples:
cgfxShaderNode.h, GLSLShaderNode.h, and hwManagedTextureShader.cpp.

bool MPxHwShaderNode::invertTexCoords (  )  const [virtual]

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.

Returns:
true if inverted texture coordinates are required, false otherwise
Examples:
cgfxShaderNode.h.

const MDagPath & MPxHwShaderNode::currentPath (  )  const

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:

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.

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

unsigned int MPxHwShaderNode::dirtyMask (  )  const

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".
Returns:
The dirty mask which can be bit 'AND'ed against the MPxHwShaderNode::DirtyMask enum.
Examples:
GLSLShaderNode.h.

int MPxHwShaderNode::normalsPerVertex (  )  [virtual]

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.

Returns:
The number of normal values desired. (0 = none, 1 = surface normal only, 2 = surface normal + tangent, 3 = surface normal + tangent + binormal)
Examples:
cgfxShaderNode.h, GLSLShaderNode.h, hwAnisotropicShader_NV20.h, hwColorPerVertexShader.cpp, hwDecalBumpShader_NV20.h, hwManagedTextureShader.cpp, hwPhongShader.h, hwReflectBumpShader_NV20.h, hwRefractReflectShader_NV20.h, hwToonShader_NV20.h, hwUnlitShader.h, and pnTrianglesNode.h.

int MPxHwShaderNode::colorsPerVertex (  )  [virtual]

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.

Returns:
The number of color values desired
Examples:
cgfxShaderNode.h, GLSLShaderNode.h, hwColorPerVertexShader.cpp, and pnTrianglesNode.h.

int MPxHwShaderNode::getColorSetNames ( MStringArray &  names  )  [virtual]

NO SCRIPT SUPPORT.

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.

Parameters:
[in]  names  a string array holding the names of the color per vertex sets from which color data should be extracted.
Returns:
The number of elements in the names array.
Examples:
cgfxShaderNode.h, and GLSLShaderNode.h.

int MPxHwShaderNode::texCoordsPerVertex (  )  [virtual]

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.
Returns:
The number of texture coordinate values desired
Examples:
GLSLShaderNode.h, hwAnisotropicShader_NV20.h, hwColorPerVertexShader.cpp, hwDecalBumpShader_NV20.h, hwManagedTextureShader.cpp, hwPhongShader.h, hwReflectBumpShader_NV20.h, hwRefractReflectShader_NV20.h, hwToonShader_NV20.h, hwUnlitShader.h, and pnTrianglesNode.h.

int MPxHwShaderNode::getTexCoordSetNames ( MStringArray &  names  )  [virtual]

NO SCRIPT SUPPORT.

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.

Parameters:
[in]  names  a string array holding the names of the uvSets from which texture coordinate data should be extracted.
Returns:
The number of elements in the names array.
Examples:
cgfxShaderNode.h, GLSLShaderNode.h, and hwPhongShader.h.

bool MPxHwShaderNode::hasTransparency (  )  [virtual]

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.

Returns:
true if the object will be transparent or false if it will not.
Examples:
cgfxShaderNode.h, hwColorPerVertexShader.cpp, and hwUnlitShader.h.

bool MPxHwShaderNode::provideVertexIDs (  )  [virtual]

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

Returns:
true if vertex IDs should be provided to the geometry method.
Examples:
blindDataShader.h.

unsigned int MPxHwShaderNode::transparencyOptions (  )  [virtual]

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.
Returns:
Integer containing the appropriate options set via masks.
Examples:
cgfxShaderNode.h.

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

NO SCRIPT SUPPORT.

Maya will call this method to get your shader's list of images which are available for use 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.

Parameters:
[in]  uvSetName  Name of a UV set the channel list should be filtered against.
[out]  imageNames  Array in which to return the names of the images this shader defines which are valid for the uvSetName specified.
Returns:
Status code
Status Codes:

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

NO SCRIPT SUPPORT.

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 must return the dimensions of the image in the 'imageWidth' and 'imageHeight' parameters so that Maya can perform pixel snapping and other resolution-dependent operations.

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();
Parameters:
[in]  imageName  Name of the image to render. This corresponds to one of the image names returned by your shader's getAvailableImages() method.
[in]  region  Rectangular region to be rendered. The values of this parameter should be used to populate the vertex and texture coordinates of the rectangle being rendered.
[out]  imageWidth  Native width (e.g. texture pixel width) of the image. This should be for the entire image, not just the portion within 'region'.
[out]  imageHeight  Native height (e.g. texture pixel height) of the image. This should be for the entire image, not just the portion within 'region'.
Returns:
Status code
Status Codes:

MStatus MPxHwShaderNode::renderSwatchImage ( MImage &  image  )  [virtual]

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().
Parameters:
[in,out]  image  Image object to which this method must write the rendered swatch. On input the image's dimensions are already set and pixel storage already allocated.
Returns:
Status code
Status Codes:
Examples:
cgfxShaderNode.h, GLSLShaderNode.h, hwColorPerVertexShader.cpp, and hwPhongShader.h.

MPxHwShaderNode * MPxHwShaderNode::getHwShaderNodePtr ( MObject &  object  )  [static]

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).

Parameters:
[in]  object  The object to examine.
Returns:
A pointer to an MPxHwShaderNode. If the method failed for any reason then a 0 (null) will be returned.

MObject MPxHwShaderNode::currentShadingEngine (  )  const

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:

Returns:
The shading engine currently being rendered.
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