---
name: "SoCallback"
section: "3iv"
platform: "linux"
package: "inventor-doc"
version: "2.1.6+ds-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/SoCallback/3iv"
---

# SoCallback(3iv)

provides custom behavior during actions

## NAME

SoCallback — provides custom behavior during actions

## INHERITS FROM

SoBase \> SoFieldContainer \> SoNode \> SoCallback

## SYNOPSIS

**#include \<Inventor/nodes/SoCallback.h\>**

**typedef void**	**SoCallbackCB(void \*userData, SoAction \*action)**

Methods from class SoCallback:

	**SoCallback()**\
 **void**	**setCallback(SoCallbackCB \*func, void \*userData = NULL)**\
 **static SoType**	**getClassTypeId()**

Methods from class SoNode:

**void**	**setOverride(SbBool state)**\
 **SbBool**	**isOverride() const**\
 **SoNode \***	**copy(SbBool copyConnections = FALSE) const**\
 **virtual SbBool**	**affectsState() const**\
 **static SoNode \***	**getByName(const SbName &name)**\
 **static int**	**getByName(const SbName &name, SoNodeList &list)**

Methods from class SoFieldContainer:

**void**	**setToDefaults()**\
 **SbBool**	**hasDefaultValues() const**\
 **SbBool**	**fieldsAreEqual(const SoFieldContainer \*fc) const**\
 **void**	**copyFieldValues(const SoFieldContainer \*fc, SbBool copyConnections = FALSE)**\
 **SbBool**	**set(const char \*fieldDataString)**\
 **void**	**get(SbString &fieldDataString)**\
 **virtual int**	**getFields(SoFieldList &resultList) const**\
 **virtual SoField \***	**getField(const SbName &fieldName) const**\
 **SbBool**	**getFieldName(const SoField \*field, SbName &fieldName) const**\
 **SbBool**	**isNotifyEnabled() const**\
 **SbBool**	**enableNotify(SbBool flag)**

Methods from class SoBase:

**void**	**ref()**\
 **void**	**unref() const**\
 **void**	**unrefNoDelete() const**\
 **void**	**touch()**\
 **virtual SoType**	**getTypeId() const**\
 **SbBool**	**isOfType(SoType type) const**\
 **virtual void**	**setName(const SbName &name)**\
 **virtual SbName**	**getName() const**

## DESCRIPTION

**This node provides a general mechanism for inserting callback functions into a scene graph. The callback function registered with the node is called each time the node is traversed while performing any** **scene graph action. The callback function is passed a pointer to the action being performed and a user data pointer registered with the callback function. You can use this node to make nonstandard OpenGL** **calls while rendering. If you do, be careful not to interfere with Inventor's use of OpenGL.**

**If you use a callback node for GL rendering, you should be careful to follow render caching rules. If your callback** **node can make different rendering calls each time it is traversed, it cannot be cached. In such a case, the node should invalidate any open caches, as in the following example:**

```
void
myCallbackFunc(void *d, SoAction *action) {
    if (action->isOfType(SoGLRenderAction::getClassTypeId())) {
	// Make my custom GL calls
	((MyClass *) d)->myRender();
	// Invalidate the state so that a cache is not made
	SoCacheElement::invalidate(action->getState());
    }
}
```

## METHODS

	**SoCallback()**\
 Creates a callback node with default settings.

**void**	**setCallback(SoCallbackCB \*func, void \*userData = NULL)**\
 Sets pointer to callback function and user data. By default, the function pointer in the node is NULL and does nothing.

**static SoType**	**getClassTypeId()**\
 Returns type identifier for this class.

## ACTION BEHAVIOR

**SoGLRenderAction, SoBoundingBoxAction, SoPickAction**\
 Calls the specified callback function for all actions.

## FILE FORMAT/DEFAULTS

```
Callback {
}
```

## SEE ALSO

**SoAction, SoCallbackAction, SoEventCallback**