Class TCastleBehavior

Continuously occuring event, for various tasks.

Parameters

RemoveMe

Set this to rtRemove or rtRemoveAndFree to remove this component from Parent after this call finished. rtRemoveAndFree additionally will free this item. Initially it's rtNone when this method is called.

Event called right before rendering the parent TCastleTransform.

Override this is you have to adjust the parent transformation strictly before the rendering, and doing it in Update is not enough.

E.g. this makes sense to implement billboard, because user must never see artifacts caused by billboard not perfectly aligned with the camera (blending sort along camera direction in sort3D is not perfect if billboard doesn't exactly match camera direction).

Overriding this also allows to adjust transformation before rendering each occurrence of TCastleTransform in the viewport tree. This matters if given TCastleTransform may occur multiple times in the viewport tree, directly or through TCastleTransformReference. This also matters if given TCastleTransform may be present in multiple viewports (see https://castle-engine.io/multiple_viewports_to_display_one_world).

Parameters

ParentParentWorldTransform

World transform of the parent of the parent of this behavior. The name is kind of convoluted, but consistent: When the parent of this behavior has exactly one parent TCastleTransform (not zero, not more) then ParentParentWorldTransform is equivalent to Parent.Parent.WorldTransform.

ParentParentWorldInverseTransform

Inverse world transform of the parent of the parent of this behavior.

ParentWorldTransform

World transform of the parent of this behavior. Equal to Parent.WorldTransform, if the Parent exists exactly once in the viewport.

ParentWorldInverseTransform

Inverse world transform of the parent of this behavior.

CameraView

Current camera vectors, in world coordinates, used to render the scene now.

Warning: this symbol is deprecated: Use ParentAfterAttach / ParentBeforeDetach or WorldAfterAttach / WorldBeforeDetach

Called after Parent changed, at the end of TCastleTransform.AddBehavior, TCastleTransform.RemoveBehavior.

Called after Parent changed, e.g. at the end of TCastleTransform.AddBehavior.

Called before Parent changed, e.g. at the beginning of TCastleTransform.RemoveBehavior.

This is also called at the destruction of behavior (more precisely from BeforeDestruction now). Even in this case, we guarantee that Parent is still valid during this call, and not in half-destroyed state. Before the actual destructor of TCastleBehavior we do BeforeParentDetach and BeforeWorldDetach and set Parent to Nil.

Called after Parent became part of World. Called only if ListenWorldChange is True.

Called before Parent stops being part of World. Called only if ListenWorldChange is True.

This is also called at the destruction of behavior (more precisely from BeforeDestruction now). Even in this case, we guarantee that Parent is still valid during this call, and not in half-destroyed state. Before the actual destructor of TCastleBehavior we do BeforeParentDetach and BeforeWorldDetach and set Parent to Nil.

Check can this behavior be added to NewParent. When this returns False, it has to set also ReasonWhyCannot. When overriding this, you can use e.g. this code to make sure we are the only behavior of given class:

function TCastleBillboard.CanAttachToParent(const NewParent: TCastleTransform;
  out ReasonWhyCannot: String): Boolean;
begin
  Result := inherited;
  if not Result then Exit;

  if NewParent.FindBehavior(TCastleBillboard) <> nil then
  begin
    ReasonWhyCannot := 'Only one TCastleBillboard behavior can be added to a given TCastleTransform';
    Result := false;
  end;
end;

This item has no description.

// Not used in the end, for now the TransformDesigning and these methods are commented out.

{ Create design-time things that are not displayed in the hierarchy so can be created after behavior selection in editor hierarchy } procedure DesigningBegin; virtual;

{ Destroy design-time stuff. } procedure DesigningEnd; virtual;

Parent TCastleTransform of this behavior. Change it by doing TCastleTransform.AddBehavior, TCastleTransform.RemoveBehavior.

Nil if this behavior is not yet added to a parent.

Set this to True to receive WorldBeforeDetach, WorldAfterAttach calls.