org.j3d.aviatrix3d
Class AlphaAttributes

java.lang.Object
  org.j3d.aviatrix3d.SceneGraphObject
      org.j3d.aviatrix3d.NodeComponent
          org.j3d.aviatrix3d.AlphaAttributes

All Implemented Interfaces:

java.lang.Comparable, AppearanceAttributeRenderable, ObjectRenderable, Renderable

public class AlphaAttributes
extends NodeComponent
implements AppearanceAttributeRenderable

Describes attributes used for controlling alpha test state during any drawing operations.

Note

Use of this class will automatically cause the containing appearance and shape nodes to be placed in to the transparency sort bucket of the rendering operations rather than state sorted. Use of this class sparingly is suggested as alpha testing/blending is performed by the rendering pipeline separately. The default blending mode is set up to mimic the defaults used by OpenGL. However, this class should only be used when the GL_ARB_imaging subset is available. This code automatically checks for it's existance and will disable calling itself if it detects the lack of existance.

Default Values

When intialised, this class follows the default OpenGL values for alpha testing:

 Alpha Function:    GL_ALWAYS
 Alpha test value:  0.0
 

Internationalisation Resource Names

• invalidAlphaFunctionMsg: Error message when the given function type does not match one of the available types.
• invalidAlphaRangeMsg: Error message when the given depth value is not in the range [0,1].

Version:

$Revision: 2.3 $

Author:

Justin Couch

Field Summary

static int	FUNCTION_ALWAYS Comparison function that always passes.
static int	FUNCTION_EQUAL Comparison function that passes if current alpha == test alpha.
static int	FUNCTION_GREATER Comparison function that passes if current alpha > test alpha.
static int	FUNCTION_GREATER_OR_EQUAL Comparison function that passes if current alpha >= test alpha.
static int	FUNCTION_LESS Comparison function that passes if current alpha < test alpha.
static int	FUNCTION_LESS_OR_EQUAL Comparison function that passes if current alpha <= test alpha.
static int	FUNCTION_NEVER Comparison function that always fails.
static int	FUNCTION_NOTEQUAL Comparison function that passes if current alpha is not equal range.

Fields inherited from class org.j3d.aviatrix3d.NodeComponent

lastParent, liveCount, parentList

Fields inherited from class org.j3d.aviatrix3d.SceneGraphObject

alive, LISTENER_SET_TIMING_ERR_PROP, updateHandler

Fields inherited from interface org.j3d.aviatrix3d.rendering.AppearanceAttributeRenderable

ALPHA_ATTRIBUTE, BLEND_ATTRIBUTE, DEPTH_ATTRIBUTE, LINE_ATTRIBUTE, POINT_ATTRIBUTE, POLYGON_ATTRIBUTE, STENCIL_ATTRIBUTE

Constructor Summary

AlphaAttributes()
Constructs a attribute set with default values as specified above.

Method Summary

int	compareTo(AlphaAttributes aa) Compares this object with the specified object for order.
int	compareTo(java.lang.Object o) Compares this object with the specified object for order.
boolean	equals(AlphaAttributes aa) Compares this object with the specified object to check for equivalence.
boolean	equals(java.lang.Object o) Compare this object for equality to the given object.
float	getAlphaCutoff() Get the current cutoff component value.
int	getAlphaFunction() Get the current operation used when the alpha tests pass.
int	getAttributeType() Get the type this visual attribute represents.
void	postRender(javax.media.opengl.GL gl) Restore all openGL state to the given drawable.
void	render(javax.media.opengl.GL gl) Issue ogl commands needed for this component
void	setAlphaCutoff(float value) Set the cutoff value for alpha blending.
void	setAlphaFunction(int func) Set the determines whether the alpha tests passes.

Methods inherited from class org.j3d.aviatrix3d.NodeComponent

addParent, getParents, numParents, removeParent

Methods inherited from class org.j3d.aviatrix3d.SceneGraphObject

checkForCyclicChild, checkForCyclicParent, dataChanged, getAppUpdateWriteTimingMessage, getBoundsWriteTimingMessage, getDataWriteTimingMessage, getUserData, isLive, setLive, setUpdateHandler, setUserData

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

FUNCTION_NEVER

public static final int FUNCTION_NEVER

Comparison function that always fails.

See Also:

Constant Field Values

FUNCTION_LESS

public static final int FUNCTION_LESS

Comparison function that passes if current alpha < test alpha.

See Also:

Constant Field Values

FUNCTION_LESS_OR_EQUAL

public static final int FUNCTION_LESS_OR_EQUAL

Comparison function that passes if current alpha <= test alpha.

See Also:

Constant Field Values

FUNCTION_GREATER

public static final int FUNCTION_GREATER

Comparison function that passes if current alpha > test alpha.

See Also:

Constant Field Values

FUNCTION_GREATER_OR_EQUAL

public static final int FUNCTION_GREATER_OR_EQUAL

Comparison function that passes if current alpha >= test alpha.

See Also:

Constant Field Values

FUNCTION_EQUAL

public static final int FUNCTION_EQUAL

Comparison function that passes if current alpha == test alpha.

See Also:

Constant Field Values

FUNCTION_NOTEQUAL

public static final int FUNCTION_NOTEQUAL

Comparison function that passes if current alpha is not equal range.

See Also:

Constant Field Values

FUNCTION_ALWAYS

public static final int FUNCTION_ALWAYS

Comparison function that always passes.

See Also:

Constant Field Values

Constructor Detail

AlphaAttributes

public AlphaAttributes()

Constructs a attribute set with default values as specified above.

Method Detail

getAttributeType

public int getAttributeType()

Get the type this visual attribute represents.

Specified by:

getAttributeType in interface AppearanceAttributeRenderable

Returns:

One of the _ATTRIBUTE constants

render

public void render(javax.media.opengl.GL gl)

Issue ogl commands needed for this component

Specified by:

render in interface ObjectRenderable

Parameters:

gl - The gl context to draw with

postRender

public void postRender(javax.media.opengl.GL gl)

Restore all openGL state to the given drawable. Does nothing as it assumes the system will disable blending outside of this class.

Specified by:

postRender in interface ObjectRenderable

Parameters:

gl - The gl context to draw with

compareTo

public int compareTo(java.lang.Object o)
              throws java.lang.ClassCastException

Compares this object with the specified object for order. Returns a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object.

Specified by:

compareTo in interface java.lang.Comparable

Parameters:

o - The objec to be compared

Returns:

-1, 0 or 1 depending on order

Throws:

java.lang.ClassCastException - The specified object's type prevents it from being compared to this Object

equals

public boolean equals(java.lang.Object o)

Compare this object for equality to the given object.

Specified by:

equals in interface Renderable

Overrides:

equals in class java.lang.Object

Parameters:

o - The object to be compared

Returns:

True if these represent the same values

setAlphaFunction

public void setAlphaFunction(int func)
                      throws java.lang.IllegalArgumentException,
                             InvalidWriteTimingException

Set the determines whether the alpha tests passes. This should be one of the FUNCTION_ constants at the top of this class.

Parameters:

func - One of the FUNCTION_ constants

Throws:

InvalidWriteTimingException - An attempt was made to write outside of the NodeUpdateListener data changed callback method

java.lang.IllegalArgumentException - The operation value was not one of the valid types.

getAlphaFunction

public int getAlphaFunction()

Get the current operation used when the alpha tests pass.

Returns:

One of the FUNCTION_ constants

setAlphaCutoff

public void setAlphaCutoff(float value)
                    throws java.lang.IllegalArgumentException,
                           InvalidWriteTimingException

Set the cutoff value for alpha blending. The cut off is compared against the current alpha value, so must be in the range [0,1]. The default value is 0.

Parameters:

value - The alpha component cut off value to use

Throws:

InvalidWriteTimingException - An attempt was made to write outside of the NodeUpdateListener data changed callback method

java.lang.IllegalArgumentException - The cutoff value was outside the range [0,1]

getAlphaCutoff

public float getAlphaCutoff()

Get the current cutoff component value. The default value is 0.

Returns:

A value in the range [0,1]

compareTo

public int compareTo(AlphaAttributes aa)

Compares this object with the specified object for order. Returns a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object.

Parameters:

aa - The attributes instance to be compared

Returns:

-1, 0 or 1 depending on order

equals

public boolean equals(AlphaAttributes aa)

Compares this object with the specified object to check for equivalence.

Parameters:

aa - The attributes instance to be compared

Returns:

true if the objects represent identical values