coin_elements(3)                     Coin                     coin_elements(3)

NAME
       coin_elements - Element Classes

        - The element classes in Coin are the containers of state information
       during action traversals of scene graphs.


SYNOPSIS
   Classes
       class SoGLCacheContextElement
           The SoGLCacheContextElement class handles the OpenGL cache for a
           context.
       class SoGLClipPlaneElement
           The SoGLClipPlaneElement class is yet to be documented.
       class SoGLColorIndexElement
           The SoGLColorIndexElement class sets the current OpenGL color.
       class SoGLCoordinateElement
           The SoGLCoordinateElement class is yet to be documented.
       class SoGLDepthBufferElement
           The SoGLDepthBufferElement controls the OpenGL depth buffer.
       class SoGLDrawStyleElement
           The SoGLDrawStyleElement updates the current draw style in OpenGL.
       class SoGLEnvironmentElement
           The SoGLEnvironmentElement class is for setting GL fog etc.
       class SoGLLazyElement
           The SoGLLazyElement class is meant to optimize GL rendering.
       class SoGLLightIdElement
           The SoGLLightIdElement class is yet to be documented.
       class SoGLLinePatternElement
           The SoGLLinePatternElement class changes the line stipple pattern
           of the OpenGL render state.
       class SoGLLineWidthElement
           The SoGLLineWidthElement class changes the line width setting of
           the OpenGL render state.
       class SoGLModelMatrixElement
           The SoGLModelMatrixElement class is yet to be documented.
       class SoGLMultiTextureCoordinateElement
           The SoGLMultiTextureCoordinateElement class stores the current
           gltexture coordinates for several units.
       class SoGLMultiTextureEnabledElement
           The SoGLMultiTextureEnabledElement class is an element which
           controls whether texturing is enabled or not.
       class SoGLMultiTextureMatrixElement
           The SoGLMultiTextureMatrixElement class is used to update the
           OpenGL texture matrix.
       class SoGLMultiTextureImageElement
           The SoGLMultiTextureImageElement class is used to control the
           current GL texture for texture units.
       class SoGLNormalElement
           The SoGLNormalElement class is yet to be documented.
       class SoGLPointSizeElement
           The SoGLPointSizeElement class changes the point size setting of
           the OpenGL render state.
       class SoGLPolygonOffsetElement
           The SoGLPolygonOffsetElement class is yet to be documented.
       class SoGLProjectionMatrixElement
           The SoGLProjectionMatrixElement class is yet to be documented.
       class SoGLRenderPassElement
           The SoGLRenderPassElement class is yet to be documented.
       class SoGLShapeHintsElement
           The SoGLShapeHintsElement class is yet to be documented.
       class SoGLUpdateAreaElement
           The SoGLUpdateAreaElement class is yet to be documented.
       class SoGLVBOElement
           The SoGLVBOElement class is used to store VBO state.
       class SoGLViewingMatrixElement
           The SoGLViewingMatrixElement class is used to store the current
           viewing matrix.
       class SoGLViewportRegionElement
           The SoGLViewportRegionElement class is yet to be documented.
       class SoGLDisplayList
           The SoGLDisplayList class stores and manages OpenGL display lists.
       class SoGLVertexAttributeElement
           The SoGLVertexAttributeElement class is yet to be documented.
       class SoAccumulatedElement
           The SoAccumulatedElement class is an abstract class for storing
           accumulated state.
       class SoAmbientColorElement
           The SoAmbientColorElement class is yet to be documented.
       class SoAnnoText3CharOrientElement
           The SoAnnoText3CharOrientElement class is yet to be documented.
       class SoAnnoText3FontSizeHintElement
           The SoAnnoText3FontSizeHintElement class is yet to be documented.
       class SoAnnoText3RenderPrintElement
           The SoAnnoText3RenderPrintElement class is yet to be documented.
       class SoBBoxModelMatrixElement
           The SoBBoxModelMatrixElement class keeps track of the current model
           matrix during a scene graph traversal. It is used by amongst others
           the SoGetBoundingBoxAction class.
       class SoBumpMapElement
           The SoBumpMapElement class is yet to be documented.
       class SoBumpMapCoordinateElement
           The SoBumpMapCoordinateElement class is yet to be documented.
       class SoBumpMapMatrixElement
           The SoBumpMapMatrixElement class is used to manage the bump map
           matrix stack.
       class SoCacheElement
           The SoCacheElement class stores and manages the open caches.
       class SoCacheHintElement
           The SoCacheHintElement class is yet to be documented.
       class SoClipPlaneElement
           The SoClipPlaneElement class is used to manage the clip plane
           stack.
       class SoComplexityElement
           The SoComplexityElement class contains the current shape complexity
           for a graph traverser.
       class SoComplexityTypeElement
           The SoComplexityTypeElement class is yet to be documented.
       class SoCoordinateElement
           The SoCoordinateElement class is yet to be documented.
       class SoCreaseAngleElement
           The SoCreaseAngleElement class stores the crease angle during a
           scene graph traversal.
       class SoCullElement
           The SoCullElement class is used internally for render and pick
           culling.
       class SoDecimationPercentageElement
           The SoDecimationPercentageElement class is yet to be documented.
       class SoDecimationTypeElement
           The SoDecimationTypeElement class is yet to be documented.
       class SoDepthBufferElement
           The SoDepthBufferElement controls the depth buffer settings.
       class SoDiffuseColorElement
           The SoDiffuseColorElement class is yet to be documented.
       class SoDrawStyleElement
           The SoDrawStyleElement class is yet to be documented.
       class SoElement
           SoElement is the abstract base class for all elements.
       class SoEmissiveColorElement
           The SoEmissiveColorElement class is yet to be documented.
       class SoEnvironmentElement
           The SoEnvironmentElement class is yet to be documented.
       class SoFloatElement
           SoFloatElement is an abstract base class for elements that consists
           of a single float value.
       class SoFocalDistanceElement
           The SoFocalDistanceElement class is yet to be documented.
       class SoFontNameElement
           The SoFontNameElement class is yet to be documented.
       class SoFontSizeElement
           The SoFontSizeElement class is yet to be documented.
       class SoInt32Element
           The SoInt32Element class is the base class for elements that simply
           store a 32-bit integer.
       class SoLazyElement
           The SoLazyElement class is used to handle material and shape
           properties.
       class SoLightAttenuationElement
           The SoLightAttenuationElement class is yet to be documented.
       class SoLightElement
           The SoLightElement class manages the currently active light
           sources.
       class SoLightModelElement
           The SoLightModelElement class is yet to be documented.
       class SoLinePatternElement
           The SoLinePatternElement class defines the line stipple pattern.
       class SoLineWidthElement
           The SoLineWidthElement class changes the line width setting of the
           render state.
       class SoLocalBBoxMatrixElement
           The SoLocalBBoxMatrixElement class is yet to be documented.
       class SoMaterialBindingElement
           The SoMaterialBindingElement class is yet to be documented.
       class SoVertexAttributeBindingElement
           The SoVertexAttributeBindingElement class is yet to be documented.
       class SoMultiTextureCoordinateElement
           The SoMultiTextureCoordinateElement class is yet to be documented.
       class SoMultiTextureEnabledElement
           The SoMultiTextureEnabledElement class is an element which stores
           whether texturing is enabled or not.
       class SoMultiTextureMatrixElement
           The SoMultiTextureMatrixElement class is used to manage the texture
           matrix stack for texture units > 0.
       class SoMultiTextureImageElement
           The SoMultiTextureImageElement class is yet to be documented.
       class SoModelMatrixElement
           The SoModelMatrixElement class is used to manage the current
           transformation.
       class SoNormalBindingElement
           The SoNormalBindingElement is yet to be documented.
       class SoNormalElement
           The SoNormalElement class is yet to be documented.
       class SoOverrideElement
           The SoOverrideElement maintains a list of overridable elements and
           a list over which elements should be overridden.
       class SoPickRayElement
           The SoPickRayElement class is yet to be documented.
       class SoPickStyleElement
           The SoPickStyleElement is yet to be documented.
       class SoPointSizeElement
           The SoPointSizeElement changes the point size setting of the render
           state.
       class SoPolygonOffsetElement
           The SoPolygonOffsetElement class is yet to be documented.
       class SoProfileCoordinateElement
           The SoProfileCoordinateElement class is yet to be documented.
       class SoProfileElement
           The SoProfileElement class is yet to be documented.
       class SoProjectionMatrixElement
           The SoProjectionMatrixElement class is yet to be documented.
       class SoReplacedElement
           The SoReplacedElement class is an abstract element superclass.
       class SoShapeHintsElement
           The SoShapeHintsElement class is yet to be documented.
       class SoShapeStyleElement
           The SoShapeStyleElement class is yet to be documented.
       class SoShininessElement
           The SoShininessElement class is yet to be documented.
       class SoSpecularColorElement
           The SoSpecularColorElement is yet to be documented.
       class SoSwitchElement
           The SoSwitchElement class is yet to be documented.
       class SoTextOutlineEnabledElement
           The SoTextOutlineEnabledElement class is yet to be documented.
       class SoTextureCombineElement
           The SoTextureCombineElement class is yet to be documented.
       class SoTextureCoordinateBindingElement
           The SoTextureCoordinateBindingElement class is yet to be
           documented.
       class SoTextureOverrideElement
           The SoTextureOverrideElement makes it possible to override texture
           elements.
       class SoTextureUnitElement
           The SoTextureUnitElement class is yet to be documented.
       class SoTextureQualityElement
           The SoTextureQualityElement is yet to be documented.
       class SoTransparencyElement
           The SoTransparencyElement is yet to be documented.
       class SoUnitsElement
           The SoUnitsElement class is yet to be documented.
       class SoViewVolumeElement
           The SoViewVolumeElement class is yet to be documented.
       class SoViewingMatrixElement
           The SoViewingMatrixElement class stores the world-to-camera
           transformation.
       class SoViewportRegionElement
           The SoViewportRegionElement class is yet to be documented.
       class SoWindowElement
           The SoWindowElement class is used to store current window
           attributes.
       class SoListenerPositionElement
           The SoListenerPositionElement holds the position of the current
           listener.
       class SoListenerOrientationElement
           The SoListenerOrientationElement holds the orientation of the
           current listener.
       class SoListenerGainElement
           The SoListenerGainElement class stores the SoListener gain during a
           scene graph traversal.
       class SoListenerDopplerElement
           The SoListenerDopplerElement holds the Doppler velocity and factor
           of the current listener.
       class SoSoundElement
           The SoSoundElement is used for optimizing audio rendering and for
           turning off inactive SoVRMLSound nodes.
       class SoVertexAttributeElement
           The SoVertexAttributeElement class is yet to be documented.
       class SoShadowStyleElement
           The SoShadowStyleElement class is yet to be documented.
       class SoGLShadowCullingElement
           The SoGLShadowCullingElement class is yet to be documented.
       class SoGeoElement
           The SoGeoElement class is yet to be documented.
       class SoProfilerTopEngine
           The SoProfilerTopEngine class is yet to be documented.
       class SoNodeVisualize
           The SoNodeVisualize class is yet to be documented.

Detailed Description
       The element classes in Coin are the containers of state information
       during action traversals of scene graphs.

       One element usually corresponds to one item of information, or
       sometimes a group of related information values. The elements work like
       a stack that is pushed and popped as the action traverses in and out of
       SoSeparator nodes, and the action will always just inspect the top of
       the stack when it needs to know a value.

       Elements are internal implementation details of the workings of nodes
       and actions, and is not something one needs to worry about before
       writing ones own extension nodes. Writing extension elements is even
       more removed from plain Open Inventor usage, but is fully possible for
       the experienced Open Inventor developer. The Element Classes

       Elements are mostly internal to Coin, unless you create new extension
       nodes over Coin. Then you will probably need to know about them.
        Elements are part of the design for scene graph traversal in Coin.
        It works like this: any traversal action instantiates and keeps a
       single SoState instance during traversal. The SoState instance uses
       SoElement objects as 'memory units' to keep track of the current state
       for any feature of the scene graph nodes.
        As an example, consider the SoPointSize node: when the SoPointSize
       node is traversed by for instance a SoGLRenderAction, it will itself
       push a SoPointSizeElement onto the SoGLRenderAction's SoState stack.
       Later, when a SoPointSet node occurs in the scene graph, it will
       request the current point size value from the SoState by reading off
       the value of its SoPointSizeElement.
        SoSeparator nodes will push and pop elements on and off the state
       stack, so anything that changes state below a SoSeparator node will not
       influence anything above the SoSeparator.

       For more information on the theoretical underpinnings of this traversal
       design, you should consider reading available literature on the so-
       called 'Visitor pattern'. We recommend 'Design Patterns', by Gamma,
       Helm, Johnson, Vlissides (aka the 'Gang Of Four'). This book actually
       uses the Inventor API traversal mechanism as the case study for
       explaining the Visitor pattern.
        For extending the Coin library with your own classes, we strongly
       recommend that you make yourself acquainted with the excellent The
       Inventor Toolmaker book (ISBN 0-201-62493-1), which describes the tasks
       involved in detail. This book was written by the original SGI Inventor
       designers and explains many of the underlying design ideas, as well as
       having lots of hands-on examples on how to extend the Coin toolkit in
       ways that are true to the fundamental design ideas. (The Inventor
       Toolmaker is also available at SGI's online library, at no cost. See
       Download The Inventor Toolmaker.) Reading the source code of the
       built-in classes in Coin should also prove very helpful.

        The following is a complete example on how to extend Coin with your
       own traversal elements. First, the class declaration of the new element
       (i.e. the header include file):

       // [texturefilenameelement.h]
       #ifndef TEXTUREFILENAMEELEMENT_H
       #define TEXTUREFILENAMEELEMENT_H

       #include <Inventor/elements/SoReplacedElement.h>
       #include <Inventor/SbString.h>

       class TextureFilenameElement : public SoReplacedElement {
         typedef SoReplacedElement inherited;

         SO_ELEMENT_HEADER(TextureFilenameElement);
       public:
         static void initClass(void);

         virtual void init(SoState * state);
         static void set(SoState * const state, SoNode * const node,
                         const SbString & filename);
         static const SbString & get(SoState * const state);
         static const TextureFilenameElement * getInstance(SoState * state);

       protected:
         virtual ~TextureFilenameElement();
         virtual void setElt(const SbString & filename);

       private:
         SbString filename;
       };

       #endif // !TEXTUREFILENAMEELEMENT_H

       The implementation of the element:

       // [texturefilenameelement.cpp]
       //
       // The purpose of the code in this file is to demonstrate how you can
       // make your own elements for scene graph traversals.
       //
       // Code by Peder Blekken <pederb@sim.no>. Copyright (C)
       // Kongsberg Oil & Gas Technologies.

       #include "texturefilenameelement.h"


       SO_ELEMENT_SOURCE(TextureFilenameElement);


       void
       TextureFilenameElement::initClass(void)
       {
         SO_ELEMENT_INIT_CLASS(TextureFilenameElement, inherited);
       }

       void
       TextureFilenameElement::init(SoState * state)
       {
         this->filename = "<none>";
       }

       TextureFilenameElement::~TextureFilenameElement()
       {
       }

       void
       TextureFilenameElement::set(SoState * const state, SoNode * const node,
                                   const SbString & filename)
       {
         TextureFilenameElement * elem = (TextureFilenameElement *)
           SoReplacedElement::getElement(state, classStackIndex, node);
         elem->setElt(filename);
       }

       const SbString &
       TextureFilenameElement::get(SoState * const state)
       {
         return TextureFilenameElement::getInstance(state)->filename;
       }

       void
       TextureFilenameElement::setElt(const SbString & filename)
       {
         this->filename = filename;
       }

       const TextureFilenameElement *
       TextureFilenameElement::getInstance(SoState * state)
       {
         return (const TextureFilenameElement *)
           SoElement::getConstElement(state, classStackIndex);
       }

       And a small, standalone test application putting the new element to
       use:

       // [lstextures.cpp]
       //
       // The purpose of this file is to make a small wrapper "tool" around
       // the TextureFilenameElement extension element, just for showing
       // example code on how to make use of a user-defined custom element.
       //
       // The code goes like this:
       //
       // We initialize the element, enable it for the SoCallbackAction, read
       // a scene graph file, set callbacks on SoTexture2 and all shape nodes
       // and applies the SoCallbackAction. The callbacks will then print out
       // the texture filename information from the TextureFilenameElement
       // each time an interesting node is hit.
       //
       //
       // Code by Peder Blekken <pederb@sim.no>. Cleaned up, integrated in
       // Coin distribution and commented by Morten Eriksen
       // <mortene@sim.no>. Copyright (C) Kongsberg Oil & Gas Technologies.

       #include <Inventor/SoDB.h>
       #include <Inventor/SoInput.h>
       #include <Inventor/actions/SoCallbackAction.h>
       #include <Inventor/nodes/SoSeparator.h>
       #include <Inventor/nodes/SoTexture2.h>
       #include <Inventor/nodes/SoShape.h>
       #include <Inventor/misc/SoState.h>
       #include <cstdio>

       #include "texturefilenameelement.h"


       SoCallbackAction::Response
       pre_tex2_cb(void * data, SoCallbackAction * action, const SoNode * node)
       {
         const SbString & filename = ((SoTexture2 *)node)->filename.getValue();
         TextureFilenameElement::set(action->getState(), (SoNode *)node, filename);

         (void)fprintf(stdout, "=> New texture: %s\n",
                       filename.getLength() == 0 ?
                       "<inlined>" : filename.getString());

         return SoCallbackAction::CONTINUE;
       }

       SoCallbackAction::Response
       pre_shape_cb(void * data, SoCallbackAction * action, const SoNode * node)
       {
         const SbString & filename =
           TextureFilenameElement::get(action->getState());

         (void)fprintf(stdout, "   Texturemap on %s: %s\n",
                       node->getTypeId().getName().getString(),
                       filename.getLength() == 0 ?
                       "<inlined>" : filename.getString());

         return SoCallbackAction::CONTINUE;
       }

       void
       usage(const char * appname)
       {
         (void)fprintf(stderr, "\n\tUsage: %s <modelfile.iv>\n\n", appname);
         (void)fprintf(stderr,
                       "\tLists all texture filenames in the model file,\n"
                       "\tand on which shape nodes they are used.\n\n"
                       "\tThe purpose of this example utility is simply to\n"
                       "\tshow how to create and use an extension element for\n"
                       "\tscene graph traversal.\n\n");
       }

       int
       main(int argc, char ** argv)
       {
         if (argc != 2) {
           usage(argv[0]);
           exit(1);
         }

         SoDB::init();

         TextureFilenameElement::initClass();
         SO_ENABLE(SoCallbackAction, TextureFilenameElement);

         SoInput input;
         if (!input.openFile(argv[1])) {
           (void)fprintf(stderr, "ERROR: couldn't open file ``%s''.\n", argv[1]);
           exit(1);
         }

         SoSeparator * root = SoDB::readAll(&input);
         if (root) {
           root->ref();
           SoCallbackAction cbaction;
           cbaction.addPreCallback(SoTexture2::getClassTypeId(), pre_tex2_cb, NULL);
           cbaction.addPreCallback(SoShape::getClassTypeId(), pre_shape_cb, NULL);
           cbaction.apply(root);
           root->unref();
           return 0;
         }
         return 1;
       }

Author
       Generated automatically by Doxygen for Coin from the source code.

Version 4.0.2              Tue Dec 26 2023 17:59:22           coin_elements(3)