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#include <Inventor/nodes/SoShapeHints.h>
Inheritance diagram for SoShapeHints:
The SoShapeHints node is used to set up clues to the rendering subsystem about how particular aspects of the subsequent geometry in the scene graph should be drawn.
The default settings of the rendering system is tuned towards programmer convenience. For instance, the default is to render both sides of all polygons to make sure we avoid any "holes" in the geometry if the vertex ordering should happen to differ for different polygons.
If the programmer gives up some of this convenience and uses SoShapeHints nodes to more closely specify information about the scene graph geometry, the clues given by the SoShapeHints node(s) will then be used by the rendering subsystem to avoid certain costly operations. Significant gains in rendering speed could be seen as a result.
Be aware that the way backface culling and two-sided lighting is decided by the rendering system is not at all intuitive. Here are the common rules of how primitive shapes will render themselves with regard to how the SoShapeHints::vertexOrdering and SoShapeHints::shapeType fields are set:
(We find this strategy quite odd. It seems more sensible behavior that when vertex ordering is unknown, two-sided lighting should be enabled, since it will be difficult to know if a normal points in or out of a polygon. But for compatibility reasons we are of course sticking to the same behavior as the original SGI Inventor library.)
FILE FORMAT/DEFAULTS:
ShapeHints { vertexOrdering UNKNOWN_ORDERING shapeType UNKNOWN_SHAPE_TYPE faceType CONVEX creaseAngle 0 }
Public Types | |
enum | VertexOrdering { UNKNOWN_ORDERING = SoShapeHintsElement::UNKNOWN_ORDERING, CLOCKWISE = SoShapeHintsElement::CLOCKWISE, COUNTERCLOCKWISE = SoShapeHintsElement::COUNTERCLOCKWISE } |
enum | ShapeType { UNKNOWN_SHAPE_TYPE = SoShapeHintsElement::UNKNOWN_SHAPE_TYPE, SOLID = SoShapeHintsElement::SOLID } |
enum | FaceType { UNKNOWN_FACE_TYPE = SoShapeHintsElement::UNKNOWN_FACE_TYPE, CONVEX = SoShapeHintsElement::CONVEX } |
Public Member Functions | |
virtual SoType | getTypeId (void) const |
SoShapeHints (void) | |
virtual void | doAction (SoAction *action) |
virtual void | GLRender (SoGLRenderAction *action) |
virtual void | callback (SoCallbackAction *action) |
virtual void | getBoundingBox (SoGetBoundingBoxAction *action) |
virtual void | pick (SoPickAction *action) |
Static Public Member Functions | |
static SoType | getClassTypeId (void) |
static void | initClass (void) |
Public Attributes | |
SoSFEnum | vertexOrdering |
SoSFEnum | shapeType |
SoSFEnum | faceType |
SoSFFloat | creaseAngle |
Protected Member Functions | |
virtual const SoFieldData * | getFieldData (void) const |
virtual | ~SoShapeHints () |
Static Protected Member Functions | |
static const SoFieldData ** | getFieldDataPtr (void) |
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Enumeration of available ways to specify ordering of vertices for a polygon. |
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Enumeration of different shape types. |
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Enumeration of polygon face types.
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Constructor. |
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Destructor. |
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This static method returns the SoType object associated with objects of this class. Reimplemented from SoNode. |
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Returns the type identification of an object derived from a class inheriting SoBase. This is used for run-time type checking and "downward" casting. Usage example:
void foo(SoNode * node) { if (node->getTypeId() == SoFile::getClassTypeId()) { SoFile * filenode = (SoFile *)node; // safe downward cast, knows the type } else if (node->getTypeId().isOfType(SoGroup::getClassTypeId())) { SoGroup * group = (SoGroup *)node; // safe downward cast, knows the type } } For application programmers wanting to extend the library with new nodes, engines, nodekits, draggers or others: this method needs to be overridden in all subclasses. This is typically done as part of setting up the full type system for extension classes, which is usually accomplished by using the pre-defined macros available through for instance Inventor/nodes/SoSubNode.h (SO_NODE_INIT_CLASS and SO_NODE_CONSTRUCTOR for node classes), Inventor/engines/SoSubEngine.h (for engine classes) and so on. For more information on writing Coin extensions, see the class documentation of the toplevel superclasses for the various class groups. Implements SoBase. |
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This API member is considered internal to the library, as it is not likely to be of interest to the application programmer. Reimplemented from SoNode. |
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Returns a pointer to the class-wide field data storage object for this instance. If no fields are present, returns Reimplemented from SoFieldContainer. |
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Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system. Reimplemented from SoNode. |
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This function performs the typical operation of a node for any action. Reimplemented from SoNode. |
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Action method for the SoGLRenderAction. This is called during rendering traversals. Nodes influencing the rendering state in any way or who wants to throw geometry primitives at OpenGL overrides this method. Reimplemented from SoNode. |
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Action method for SoCallbackAction. Simply updates the state according to how the node behaves for the render action, so the application programmer can use the SoCallbackAction for extracting information about the scene graph. Reimplemented from SoNode. |
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Action method for the SoGetBoundingBoxAction. Calculates bounding box and center coordinates for node and modifies the values of the action to encompass the bounding box for this node and to shift the center point for the scene more towards the one for this node. Nodes influencing how geometry nodes calculates their bounding box also overrides this method to change the relevant state variables. Reimplemented from SoNode. |
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Action method for SoPickAction. Does common processing for SoPickAction action instances. Reimplemented from SoNode. |
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Specifies how vertices are ordered for polygon faces. Set this field to SoShapeHints::CLOCKWISE or SoShapeHints::COUNTERCLOCKWISE if possible to turn on backface culling and thereby optimize rendering. Default value is SoShapeHints::UNKNOWN_ORDERING. |
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Hint about whether or not shapes are known to be "closed". Default value is SoShapeHints::UNKNOWN_SHAPE_TYPE. |
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Hint about whether or not polygon faces are known to be convex. Default value is SoShapeHints::CONVEX. |
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When normals are automatically generated by Coin (i.e. SoNormal nodes are not used), this is the smallest angle between two faces where we would still calculate normals to do flatshading. If the angle between the normals of two neighboring faces is less than the value of this field, the faces will be smoothshaded around their common edge. |
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