# Ogre::ShadowCaster Class Reference

This class defines the interface that must be implemented by shadow casters. More...

`#include <OgreShadowCaster.h>`

Inheritance diagram for Ogre::ShadowCaster:

[legend]

List of all members.

## Public Types

typedef std::vector < ShadowRenderable * > | ShadowRenderableList
typedef VectorIterator < ShadowRenderableList > | ShadowRenderableListIterator

## Public Member Functions

virtual | ~ShadowCaster ()
virtual bool | getCastShadows (void) const =0
| Returns whether or not this object currently casts a shadow.
virtual EdgeData * | getEdgeList (void)=0
| Returns details of the edges which might be used to determine a silhouette.
virtual bool | hasEdgeList (void)=0
| Returns whether the object has a valid edge list.
virtual const AxisAlignedBox & | getWorldBoundingBox (bool derive=false) const =0
| Get the world bounding box of the caster.
virtual const AxisAlignedBox & | getLightCapBounds (void) const =0
| Gets the world space bounding box of the light cap.
virtual const AxisAlignedBox & | getDarkCapBounds (const Light &light, Real dirLightExtrusionDist) const =0
| Gets the world space bounding box of the dark cap, as extruded using the light provided.
virtual ShadowRenderableListIterator | getShadowVolumeRenderableIterator (ShadowTechnique shadowTechnique, const Light *light, HardwareIndexBufferSharedPtr *indexBuffer, bool extrudeVertices, Real extrusionDistance, unsigned long flags=0)=0
| Gets an iterator over the renderables required to render the shadow volume.
virtual Real | getPointExtrusionDistance (const Light *l) const =0
| Get the distance to extrude for a point/spot light.

## Static Public Member Functions

static void | extrudeVertices (const HardwareVertexBufferSharedPtr &vertexBuffer, size_t originalVertexCount, const Vector4 &lightPos, Real extrudeDist)
| Utility method for extruding vertices based on a light.

## Protected Member Functions

Real | getExtrusionDistance (const Vector3 &objectPos, const Light *light) const
| Helper method for calculating extrusion distance.
virtual void | updateEdgeListLightFacing (EdgeData *edgeData, const Vector4 &lightPos)
| Tells the caster to perform the tasks necessary to update the edge data's light listing.
virtual void | generateShadowVolume (EdgeData *edgeData, const HardwareIndexBufferSharedPtr &indexBuffer, const Light *light, ShadowRenderableList &shadowRenderables, unsigned long flags)
| Generates the indexes required to render a shadow volume into the index buffer which is passed in, and updates shadow renderables to use it.
virtual void | extrudeBounds (AxisAlignedBox &box, const Vector4 &lightPos, Real extrudeDist) const
| Utility method for extruding a bounding box.

## Detailed Description

This class defines the interface that must be implemented by shadow casters.

Definition at line 104 of file OgreShadowCaster.h.

## Member Typedef Documentation

typedef std::vector<ShadowRenderable*> Ogre::ShadowCaster::ShadowRenderableList

Definition at line 123 of file OgreShadowCaster.h.

typedef VectorIterator<ShadowRenderableList> Ogre::ShadowCaster::ShadowRenderableListIterator

Definition at line 124 of file OgreShadowCaster.h.

## Constructor & Destructor Documentation

virtual Ogre::ShadowCaster::~ShadowCaster | ( |  | ) | `[virtual]`

Definition at line 107 of file OgreShadowCaster.h.

## Member Function Documentation

virtual bool Ogre::ShadowCaster::getCastShadows | ( | void |  | ) | const`[pure virtual]`

Returns whether or not this object currently casts a shadow.

Implemented in Ogre::MovableObject.

virtual EdgeData* Ogre::ShadowCaster::getEdgeList | ( | void |  | ) | `[pure virtual]`

Returns details of the edges which might be used to determine a silhouette.

Implemented in Ogre::Entity, Ogre::ManualObject, Ogre::MovableObject, and Ogre::StaticGeometry::Region.

virtual bool Ogre::ShadowCaster::hasEdgeList | ( | void |  | ) | `[pure virtual]`

Returns whether the object has a valid edge list.

Implemented in Ogre::Entity, Ogre::ManualObject, Ogre::MovableObject, and Ogre::StaticGeometry::Region.

virtual const AxisAlignedBox& Ogre::ShadowCaster::getWorldBoundingBox | ( | bool | derive = `false` | ) | const`[pure virtual]`

Get the world bounding box of the caster.

Implemented in Ogre::Entity, and Ogre::MovableObject.

virtual const AxisAlignedBox& Ogre::ShadowCaster::getLightCapBounds | ( | void |  | ) | const`[pure virtual]`

Gets the world space bounding box of the light cap.

Implemented in Ogre::MovableObject.

virtual const AxisAlignedBox& Ogre::ShadowCaster::getDarkCapBounds | ( | const Light & | light,
|  | Real | dirLightExtrusionDist |
| ) |  |  | const`[pure virtual]`

Gets the world space bounding box of the dark cap, as extruded using the light provided.

Implemented in Ogre::MovableObject.

virtual ShadowRenderableListIterator Ogre::ShadowCaster::getShadowVolumeRenderableIterator | ( | ShadowTechnique | shadowTechnique,
|  | const Light * | light,
|  | HardwareIndexBufferSharedPtr * | indexBuffer,
|  | bool | extrudeVertices,
|  | Real | extrusionDistance,
|  | unsigned long | flags = `0` |
| ) |  |  | `[pure virtual]`

Gets an iterator over the renderables required to render the shadow volume.

Remarks:
  Shadowable geometry should ideally be designed such that there is only one ShadowRenderable required to render the the shadow; however this is not a necessary limitation and it can be exceeded if required.

Parameters:

  | shadowTechnique | The technique being used to generate the shadow
  | light | The light to generate the shadow from
  | indexBuffer | The index buffer to build the renderables into, the current contents are assumed to be disposable.
  | extrudeVertices | If true, this means this class should extrude the vertices of the back of the volume in software. If false, it will not be done (a vertex program is assumed).
  | extrusionDistance | The distance to extrude the shadow volume
  | flags | Technique-specific flags, see ShadowRenderableFlags

Implemented in Ogre::Entity, Ogre::ManualObject, Ogre::MovableObject, and Ogre::StaticGeometry::Region.

static void Ogre::ShadowCaster::extrudeVertices | ( | const HardwareVertexBufferSharedPtr & | vertexBuffer,
|  | size_t | originalVertexCount,
|  | const Vector4 & | lightPos,
|  | Real | extrudeDist |
| ) |  |  | `[static]`

Utility method for extruding vertices based on a light.

Remarks:
  Unfortunately, because D3D cannot handle homogeneous (4D) position coordinates in the fixed-function pipeline (GL can, but we have to be cross-API), when we extrude in software we cannot extrude to infinity the way we do in the vertex program (by setting w to 0.0f). Therefore we extrude by a fixed distance, which may cause some problems with larger scenes. Luckily better hardware (ie vertex programs) can fix this.

Parameters:

  | vertexBuffer | The vertex buffer containing ONLY xyz position values, which must be originalVertexCount * 2 * 3 floats long.
  | originalVertexCount | The count of the original number of vertices, i.e. the number in the mesh, not counting the doubling which has already been done (by VertexData::prepareForShadowVolume) to provide the extruded area of the buffer.
  | lightPos | 4D light position in object space, when w=0.0f this represents a directional light
  | extrudeDist | The distance to extrude

virtual Real Ogre::ShadowCaster::getPointExtrusionDistance | ( | const Light * | l | ) | const`[pure virtual]`

Get the distance to extrude for a point/spot light.

Implemented in Ogre::MovableObject.

Real Ogre::ShadowCaster::getExtrusionDistance | ( | const Vector3 & | objectPos,
|  | const Light * | light |
| ) |  |  | const`[protected]`

Helper method for calculating extrusion distance.

virtual void Ogre::ShadowCaster::updateEdgeListLightFacing | ( | EdgeData * | edgeData,
|  | const Vector4 & | lightPos |
| ) |  |  | `[protected, virtual]`

Tells the caster to perform the tasks necessary to update the edge data's light listing.

Can be overridden if the subclass needs to do additional things.

Parameters:

  | edgeData | The edge information to update
  | lightPos | 4D vector representing the light, a directional light has w=0.0

virtual void Ogre::ShadowCaster::generateShadowVolume | ( | EdgeData * | edgeData,
|  | const HardwareIndexBufferSharedPtr & | indexBuffer,
|  | const Light * | light,
|  | ShadowRenderableList & | shadowRenderables,
|  | unsigned long | flags |
| ) |  |  | `[protected, virtual]`

Generates the indexes required to render a shadow volume into the index buffer which is passed in, and updates shadow renderables to use it.

Parameters:

  | edgeData | The edge information to use
  | indexBuffer | The buffer into which to write data into; current contents are assumed to be discardable.
  | light | The light, mainly for type info as silhouette calculations should already have been done in updateEdgeListLightFacing
  | shadowRenderables | A list of shadow renderables which has already been constructed but will need populating with details of the index ranges to be used.
  | flags | Additional controller flags, see ShadowRenderableFlags

virtual void Ogre::ShadowCaster::extrudeBounds | ( | AxisAlignedBox & | box,
|  | const Vector4 & | lightPos,
|  | Real | extrudeDist |
| ) |  |  | const`[protected, virtual]`

Utility method for extruding a bounding box.

Parameters:

  | box | Original bounding box, will be updated in-place
  | lightPos | 4D light position in object space, when w=0.0f this represents a directional light
  | extrudeDist | The distance to extrude

The documentation for this class was generated from the following file:

- OgreShadowCaster.h

Copyright © 2008 Torus Knot Software Ltd
This work is licensed under a Creative Commons Attribution-ShareAlike 2.5 License.
Last modified Sun Jul 26 11:36:58 2009