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Addition of comments for ClusterCullingCallback

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Hartwig Wiesmann 2018-02-18 08:49:41 +03:00
parent 21539466fd
commit f01383c02a
1 changed files with 27 additions and 3 deletions
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include/osg/ClusterCullingCallback
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@ -19,9 +19,33 @@
namespace osg {
/** Implements cluster culling to cull back facing drawables. Derived from
* Drawable::CullCallback.
*/
///
/// @class ClusterCullingCallback
/// @brief Implements cluster culling to cull back facing drawables. Derived from Drawable::CullCallback.
///
/// This culling callback is intended to be attached to a node using the setCullCallback method. If the
/// node is a drawable cull(osg::NodeVisitor*, osg::Drawable*, osg::State*) otherwise
/// operator()(Node*, NodeVisitor*) will be called during the cull traversal.
///
/// To decide whether the node (in case of a drawable) or its children (in case of any other node type) are
/// to be culled depends on four parameters:
/// - a control point,
/// - a normal specified at the control point,
/// - a deviation value representing the cosinus of an enclosed angle and
/// - a radius describing a sphere around the control point.
///
/// The node is culled if the following two conditions are fulfilled:
/// - the distance between the current eye/view point to the control point is larger or equal to radius,
/// - the cosinus of the enclosed angle between the normal and the vector from the control point to the eye/view point
/// is smaller(!) than the specified deviation value (normally this value is negative meaning that the enclosed angle
/// between the control point and the eye/view point is larger than the angle indirectly specified by the
/// deviation value).
///
/// @remark As the deviation is representing the cosinus of an enclosed angle its value should be within the
/// the interval [-1; 1]. A value of one will cull all nodes while a value of -1 will never cull a node.
/// The deviation will normally have negative values because then the enclosed angle between the normal and the
/// eye/view point is larger than 90 degrees (and therefore the eye sees the "back" from the control point).
///
class OSG_EXPORT ClusterCullingCallback : public DrawableCullCallback, public NodeCallback
{
public: