edu.umd.cs.jazz.scenegraph
Interface ZScenegraphObject

All Known Implementing Classes:
ZNode, ZVisualComponent
public abstract interface ZScenegraphObject

ZScenegraphObject is the base class for all objects in the jazz scenegraph. It has no purpose other than providing a common superclass for ZNode and ZVisualComponent.

Coordinate Systems
Application developers should understand the three coordinates systems (global, local, window) that exist in Jazz. Local bounds are each objects own coordinate system. It starts at 0,0 and are un-modified by any transformation and encompasses the width and height of the object. Global coorinates are an objects local coordinates modified by any applicable transforms. There is one set of global coordinates and they may also be referred to as the global space. The last type of coordinates are those that map directly to a java component. They originate at the top-left corner and increase as you progress down and to the right. 

                       // Create a basic Jazz scene
       JComponent component = buildScene(container);
                       // Extract the basic elements of the scenegraph
       ZCamera camera = surface.getCamera();
       ZNode layer = (ZNode)camera.getPaintStartPoints().firstElement();
       ZRectangle rect = new ZRectangle(10, 10, 50, 50);
       ZNode node = new ZNode(rect);
The rectangle exists in local coordinates at 10, 10. It's width and height are both 50. The bounding box of this object in local coordinates is 10, 10, 60, 60. Since there are no transforms applied to this object, it's global coords are the same as it's local coordinates. And, since there is no translation applied to the camera, the window coordinates are the same as the global coordinates. The rectangle will appear on the component at 10, 10 and have a width and height of 50.
NOTE : for this discussion, bounding boxes are expressed as x1, y1, x2, y2

Now, if the node's transform is modified by translation: 

       node.getTransform().translate(100, 100);
The rectangle's local coordiantes are unchanged. The local coordinates are transformed by the node's transform to produce the global coordinates. Since there is still no transformation applied to the camera, the window coordinates are the same as the global coordinates. The rectangle will appear on the component at 110, 110 and have a width and height of 50.

Now, if the node's transform is modified by scale: 

       node.getTransform().scale(2);
The rectangle's local coordiantes are unchanged. The local coordinates are transformed by the node's transform to produce the global coordinates (scale first, then translated). Since there is still no transformation applied to the camera, the window coordinates are the same as the global coordinates. The rectangle will appear on the component at 120, 120 and have a width and height of 100.

Now, if the camera is translated 

       camera.getCamaraTransform().translate(-100, -100);
The rectangle's local coordiantes are unchanged. The local coordinates are transformed by the node's transform to produce the global coordinates (scale first, then translated). The window coordinates are procuded by applying the cameras transform to the global coordinates. The rectangle will appear on the component at 120, 120 and have a width and height of 100.

See Also:
ZNode, ZVisualComponent

Method Summary
 void damage()
          Damage causes the portions of the surfaces that this object appears in to be marked as needing to be repainted.
 void damage(boolean boundsChanged)
           
 ZNode findNode()
          Used to find the containing object in the scenegraph hierarchy.
 void setVisualComponent(ZVisualComponent child)
          Set the visual component.
 void transformChanged(java.awt.geom.AffineTransform origTransform)
          Internal method used to notify a node that its transform has changed
 void updateBounds()
          Notifies the object that it must update it's bounds.
 void updateChildBounds()
          Notifies an object that it must update it's bounds and request that any children it has update their bounds as well.
 void updateVolatility()
          Internal method used to compute whether a node is volatile based on its children.
 

Method Detail

damage

public void damage()
Damage causes the portions of the surfaces that this object appears in to be marked as needing to be repainted. The repainting does not actually occur until ZSurface.restore() is called. public abstract void damage();
See Also:
ZNode.damage()

damage

public void damage(boolean boundsChanged)

updateBounds

public void updateBounds()
Notifies the object that it must update it's bounds.

updateChildBounds

public void updateChildBounds()
Notifies an object that it must update it's bounds and request that any children it has update their bounds as well.

setVisualComponent

public void setVisualComponent(ZVisualComponent child)
Set the visual component. Calling this method will damage the space accordingly. Be sure to call restore() on any applicable surfaces. The visual content on the surface will not be updated until a call to restore() is made.
Parameters:
vc - The new visual component

findNode

public ZNode findNode()
Used to find the containing object in the scenegraph hierarchy. ZNodes will just return themselves. ZVisualComponents will ascend the component chain and return the parenting ZNode.

updateVolatility

public void updateVolatility()
Internal method used to compute whether a node is volatile based on its children.

transformChanged

public void transformChanged(java.awt.geom.AffineTransform origTransform)
Internal method used to notify a node that its transform has changed
Parameters:
origTransform - The value of the original transform (before it was changed)