--- name: "SoAlphaTest" section: "3" platform: "linux" package: "coin" version: "1:4.0.10-1" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/SoAlphaTest" --- # SoAlphaTest(3) The SoAlphaTest class is a node used to control the GL alpha test function. ## NAME SoAlphaTest - The **SoAlphaTest** class is a node used to control the GL alpha test function. ## SYNOPSIS \#include \ Inherits **SoNode**. ### Public Types enum **Function** { **NONE**, **NEVER**, **ALWAYS**, **LESS**, **LEQUAL**, **EQUAL**, **GEQUAL**, **GREATER**, **NOTEQUAL** }\ Public Types inherited from **SoNode** enum **NodeType** { **INVENTOR** = 0x0000, **VRML1** = 0x0001, **VRML2** = 0x0002, **INVENTOR\_1** = 0x0004, **INVENTOR\_2\_0** = 0x0008, **INVENTOR\_2\_1** = 0x0010, **INVENTOR\_2\_5** = 0x0020, **INVENTOR\_2\_6** = 0x0040, **COIN\_1\_0** = 0x0080, **COIN\_2\_0** = 0x0100, **EXTENSION** = 0x0200, **COIN\_2\_2** = 0x0400, **COIN\_2\_3** = 0x0800, **COIN\_2\_4** = 0x1000, **INVENTOR\_5\_0** = 0x2000, **COIN\_2\_5** = 0x4000, **COIN\_3\_0** = 0x8000, **INVENTOR\_6\_0** = 0x10000, **COIN\_4\_0** = 0x20000 }\ ### Public Member Functions virtual **SoType** **getTypeId** (void) const\ **SoAlphaTest** (void)\ virtual void **GLRender** (**SoGLRenderAction** \*action)\ Public Member Functions inherited from **SoNode** void **setOverride** (const SbBool state)\ SbBool **isOverride** (void) const\ void **setNodeType** (const **NodeType** type)\ **NodeType** **getNodeType** (void) const\ virtual **SoNode** \* **copy** (SbBool copyconnections=FALSE) const\ virtual SbBool **affectsState** (void) const\ virtual void **doAction** (**SoAction** \*action)\ virtual void **GLRenderBelowPath** (**SoGLRenderAction** \*action)\ virtual void **GLRenderInPath** (**SoGLRenderAction** \*action)\ virtual void **GLRenderOffPath** (**SoGLRenderAction** \*action)\ virtual void **callback** (**SoCallbackAction** \*action)\ virtual void **getBoundingBox** (**SoGetBoundingBoxAction** \*action)\ virtual void **getMatrix** (**SoGetMatrixAction** \*action)\ virtual void **handleEvent** (**SoHandleEventAction** \*action)\ virtual void **pick** (**SoPickAction** \*action)\ virtual void **rayPick** (**SoRayPickAction** \*action)\ virtual void **search** (**SoSearchAction** \*action)\ virtual void **write** (**SoWriteAction** \*action)\ virtual void **audioRender** (**SoAudioRenderAction** \*action)\ virtual void **getPrimitiveCount** (**SoGetPrimitiveCountAction** \*action)\ virtual void **grabEventsSetup** (void)\ virtual void **grabEventsCleanup** (void)\ virtual void **startNotify** (void)\ virtual void **notify** (**SoNotList** \*l)\ SbUniqueId **getNodeId** (void) const\ virtual **SoChildList** \* **getChildren** (void) const\ virtual void **writeInstance** (**SoOutput** \*out)\ virtual **SoNode** \* **addToCopyDict** (void) const\ virtual void **copyContents** (const **SoFieldContainer** \*from, SbBool copyconnections)\ virtual **SoFieldContainer** \* **copyThroughConnection** (void) const\ Public Member Functions inherited from **SoFieldContainer** void **setToDefaults** (void)\ SbBool **hasDefaultValues** (void) const\ SbBool **fieldsAreEqual** (const **SoFieldContainer** \*container) const\ void **copyFieldValues** (const **SoFieldContainer** \*container, SbBool copyconnections=FALSE)\ SbBool **set** (const char \*const fielddata)\ void **get** (**SbString** &fielddata)\ virtual int **getFields** (**SoFieldList** &l) const\ virtual int **getAllFields** (**SoFieldList** &l) const\ virtual **SoField** \* **getField** (const **SbName** &name) const\ virtual **SoField** \* **getEventIn** (const **SbName** &name) const\ virtual **SoField** \* **getEventOut** (const **SbName** &name) const\ SbBool **getFieldName** (const **SoField** \*const field, **SbName** &name) const\ SbBool **enableNotify** (const SbBool flag)\ SbBool **isNotifyEnabled** (void) const\ SbBool **set** (const char \*fielddata, **SoInput** \*input)\ void **get** (**SbString** &fielddata, **SoOutput** \*out)\ virtual SbBool **validateNewFieldValue** (**SoField** \*field, void \*newval)\ virtual void **addWriteReference** (**SoOutput** \*out, SbBool isfromfield=FALSE)\ SbBool **getIsBuiltIn** (void) const\ virtual void **getFieldsMemorySize** (size\_t &managed, size\_t &unmanaged) const\ void **setUserData** (void \*userdata) const\ void \* **getUserData** (void) const\ Public Member Functions inherited from **SoBase** void **ref** (void) const\ void **unref** (void) const\ void **unrefNoDelete** (void) const\ int32\_t **getRefCount** (void) const\ void **touch** (void)\ SbBool **isOfType** (**SoType** type) const\ Returns TRUE if the type of this object is either of the same type or inherited from *type*. virtual **SbName** **getName** (void) const\ virtual void **setName** (const **SbName** &newname)\ void **addAuditor** (void \*const auditor, const **SoNotRec::Type** type)\ void **removeAuditor** (void \*const auditor, const **SoNotRec::Type** type)\ const **SoAuditorList** & **getAuditors** (void) const\ SbBool **shouldWrite** (void)\ void **assertAlive** (void) const\ ### Static Public Member Functions static **SoType** **getClassTypeId** (void)\ static void **initClass** (void)\ Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system. Static Public Member Functions inherited from **SoNode** static uint32\_t **getCompatibilityTypes** (const **SoType** &nodetype)\ static **SoType** **getClassTypeId** (void)\ static **SoNode** \* **getByName** (const **SbName** &name)\ static int **getByName** (const **SbName** &name, **SoNodeList** &l)\ static void **initClass** (void)\ Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system. static void **initClasses** (void)\ static SbUniqueId **getNextNodeId** (void)\ static int **getActionMethodIndex** (const **SoType** type)\ static void **getBoundingBoxS** (**SoAction** \*action, **SoNode** \*node)\ static void **GLRenderS** (**SoAction** \*action, **SoNode** \*node)\ static void **callbackS** (**SoAction** \*action, **SoNode** \*node)\ static void **getMatrixS** (**SoAction** \*action, **SoNode** \*node)\ static void **handleEventS** (**SoAction** \*action, **SoNode** \*node)\ static void **pickS** (**SoAction** \*action, **SoNode** \*node)\ static void **rayPickS** (**SoAction** \*action, **SoNode** \*node)\ static void **searchS** (**SoAction** \*action, **SoNode** \*node)\ static void **writeS** (**SoAction** \*action, **SoNode** \*node)\ static void **audioRenderS** (**SoAction** \*action, **SoNode** \*node)\ static void **getPrimitiveCountS** (**SoAction** \*action, **SoNode** \*node)\ Static Public Member Functions inherited from **SoFieldContainer** static void **initClass** (void)\ Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system. static **SoType** **getClassTypeId** (void)\ This static method returns the **SoType** object associated with objects of this class. static void **cleanupClass** (void)\ static void **initCopyDict** (void)\ static void **addCopy** (const **SoFieldContainer** \*orig, const **SoFieldContainer** \*copy)\ static **SoFieldContainer** \* **checkCopy** (const **SoFieldContainer** \*orig)\ static **SoFieldContainer** \* **findCopy** (const **SoFieldContainer** \*orig, const SbBool copyconnections)\ static void **copyDone** (void)\ Static Public Member Functions inherited from **SoBase** static void **initClass** (void)\ Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system. static **SoType** **getClassTypeId** (void)\ This static method returns the **SoType** object associated with objects of this class. static void **addName** (**SoBase** \*const base, const char \*const name)\ static void **removeName** (**SoBase** \*const base, const char \*const name)\ static void **incrementCurrentWriteCounter** (void)\ static void **decrementCurrentWriteCounter** (void)\ static **SoBase** \* **getNamedBase** (const **SbName** &name, **SoType** type)\ static int **getNamedBases** (const **SbName** &name, **SoBaseList** &baselist, **SoType** type)\ static SbBool **read** (**SoInput** \*input, **SoBase** \*&base, **SoType** expectedtype)\ static void **setInstancePrefix** (const **SbString** &c)\ static void **setTraceRefs** (SbBool trace)\ static SbBool **getTraceRefs** (void)\ static SbBool **connectRoute** (**SoInput** \*input, const **SbName** &fromnodename, const **SbName** &fromfieldname, const **SbName** &tonodename, const **SbName** &tofieldname)\ static SbBool **readRoute** (**SoInput** \*input)\ ### Public Attributes **SoSFEnum** **function**\ **SoSFFloat** **value**\ ### Protected Member Functions virtual const **SoFieldData** \* **getFieldData** (void) const\ virtual **~SoAlphaTest** ()\ Protected Member Functions inherited from **SoNode** **SoNode** (void)\ virtual **~SoNode** ()\ virtual SbBool **readInstance** (**SoInput** \*in, unsigned short flags)\ Protected Member Functions inherited from **SoFieldContainer** **SoFieldContainer** (void)\ virtual **~SoFieldContainer** ()\ Protected Member Functions inherited from **SoBase** **SoBase** (void)\ virtual **~SoBase** ()\ virtual void **destroy** (void)\ SbBool **hasMultipleWriteRefs** (void) const\ SbBool **writeHeader** (**SoOutput** \*out, SbBool isgroup, SbBool isengine) const\ void **writeFooter** (**SoOutput** \*out) const\ virtual const char \* **getFileFormatName** (void) const\ virtual **SoNotRec** **createNotRec** (void)\ ### Static Protected Member Functions static const **SoFieldData** \*\* **getFieldDataPtr** (void)\ Static Protected Member Functions inherited from **SoNode** static const **SoFieldData** \*\* **getFieldDataPtr** (void)\ static void **setNextActionMethodIndex** (int index)\ static int **getNextActionMethodIndex** (void)\ static void **incNextActionMethodIndex** (void)\ static void **setCompatibilityTypes** (const **SoType** &nodetype, const uint32\_t bitmask)\ Static Protected Member Functions inherited from **SoBase** static uint32\_t **getCurrentWriteCounter** (void)\ static void **staticDataLock** (void)\ static void **staticDataUnlock** (void)\ ### Additional Inherited Members Protected Types inherited from **SoBase** enum **BaseFlags** { **IS\_ENGINE** = 0x01, **IS\_GROUP** = 0x02 }\ Protected Attributes inherited from **SoNode** SbUniqueId **uniqueId**\ Protected Attributes inherited from **SoFieldContainer** SbBool **isBuiltIn**\ Static Protected Attributes inherited from **SoNode** static SbUniqueId **nextUniqueId** = 1\ static int **nextActionMethodIndex** = 0\ ## Detailed Description The **SoAlphaTest** class is a node used to control the GL alpha test function. With this node you can control the OpenGL alpha test function. The alpha test function enables you to discard fragments based on its alpha value. For instance, if you set the function to GREATER and value to 0.5, only fragments with alpha value greater than 0.5 will be rendered. Alpha testing is typically used when rendering textures where all pixels are either completely opaque or completely transparent. Transparency sorting problems are avoided when alpha testing is used instead of blending, since depth testing can still be enabled and no sorting or delayed rendering is needed. To enable alpha testing instead of transparency blending, insert a TransparencyType node with value = NONE, and an AlphaTest node with *function* set to GREATER and *value* set to for instance 0.01. **FILE FORMAT/DEFAULTS:** ``` AlphaTest { function NONE value 0.5 } ``` Be aware that this class is an extension for Coin, and it is not available in the original SGI Open Inventor v2.1 API.\ **Since** Coin 4.0 ## Member Enumeration Documentation ### enum SoAlphaTest::Function Enumeration for the various alpha functions. **Enumerator** - ***NONE*** No alpha test is performed. - ***NEVER*** Never passes. - ***ALWAYS*** Always passes. - ***LESS*** Passes if the incoming alpha value is less than the stored alpha value. - ***LEQUAL*** Passes if the incoming alpha value is less than or equal to the stored alpha value. - ***EQUAL*** Passes if the incoming alpha value is equal to the stored alpha value. - ***GEQUAL*** Passes if the incoming alpha value is greater than or equal to the stored alpha value. - ***GREATER*** Passes if the incoming alpha value is greater than the stored alpha value. - ***NOTEQUAL*** Passes if the incoming alpha value is not equal to the stored alpha value. ## Constructor & Destructor Documentation ### SoAlphaTest::SoAlphaTest (void ) Constructor. ### SoAlphaTest::~SoAlphaTest () \[protected\], \[virtual\] Destructor. ## Member Function Documentation ### SoType SoAlphaTest::getClassTypeId (void ) \[static\] This static method returns the **SoType** object associated with objects of this class. ### SoType SoAlphaTest::getTypeId (void ) const \[virtual\] Returns the type identification of an object derived from a class inheriting **SoBase**. This is used for runtime type checking and "downward" casting. Implements **SoBase**. ### const SoFieldData \*\* SoAlphaTest::getFieldDataPtr (void ) \[static\], \[protected\] *This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.*\ Returns the **SoFieldData** class which holds information about fields in this node. ### const SoFieldData \* SoAlphaTest::getFieldData (void ) const \[protected\], \[virtual\] Returns a pointer to the class-wide field data storage object for this instance. If no fields are present, returns NULL. Reimplemented from **SoFieldContainer**. ### void SoAlphaTest::GLRender (SoGLRenderAction \* action) \[virtual\] Action method for the **SoGLRenderAction**. This is called during rendering traversals. Nodes influencing the rendering state in any way or want to throw geometry primitives at OpenGL override this method. Reimplemented from **SoNode**. ## Member Data Documentation ### SoSFEnum SoAlphaTest::function Which alpha function to use. Defaults to NONE. ### SoSFFloat SoAlphaTest::value The value the function will compare against when applicable. Default is 0.5. ## Author Generated automatically by Doxygen for Coin from the source code.