javax.media.opengl

Interface GLFBODrawable

All Superinterfaces:

GLDrawable

All Known Subinterfaces:

GLFBODrawable.Resizeable, GLOffscreenAutoDrawable.FBO

public interface GLFBODrawable
extends GLDrawable

Platform-independent GLDrawable specialization, exposing FBObject functionality.

A GLFBODrawable is uninitialized until a GLContext is bound and made current the first time, hence only then it's capabilities fully reflect expectations, i.e. color, depth, stencil and MSAA bits will be valid only after the first makeCurrent() call. On-/offscreen bits are valid after setRealized(true).

MSAA is used if requested.

Double buffering is used if requested.

In MSAA mode, it always uses the implicit 2nd framebuffer sink. Hence double buffering is always the case w/ MSAA.

In non MSAA a second explicit framebuffer is being used. This method allows compliance w/ the spec, i.e. read and draw framebuffer selection and double buffer usage for e.g. glReadPixels(..). This method also allows usage of both textures seperately.

It would be possible to implement double buffering simply using FBObject.TextureAttachments with one framebuffer. This would require mode selection and hence complicate the API. Besides, it would not support differentiation of read and write framebuffer and hence not be spec compliant.

Actual swapping of the textures and/or framebuffer is performed either in the context current hook or when swapping buffers, whatever comes first.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	GLFBODrawable.Resizeable Resizeable GLFBODrawable specialization

Method Summary

Methods

Modifier and Type	Method and Description
FBObject	getFBObject(int bufferName) If MSAA is being used and GL.GL_FRONT is requested, the internal FBObject sample sink is being returned.
int	getNumBuffers()
int	getNumSamples()
FBObject.TextureAttachment	getTextureBuffer(int bufferName) Returns the named texture buffer.
int	getTextureUnit()
boolean	isInitialized()
void	resetSize(GL gl) Notify this instance about upstream size change to reconfigure the FBObject.
int	setNumBuffers(int bufferCount) Sets the number of buffers (FBO) being used if using double buffering.
void	setNumSamples(GL gl, int newSamples) Set the number of sample buffers if using MSAA
void	setTextureUnit(int unit)

Methods inherited from interface javax.media.opengl.GLDrawable

createContext, getChosenGLCapabilities, getFactory, getGLProfile, getHandle, getHeight, getNativeSurface, getWidth, isGLOriented, isRealized, setRealized, swapBuffers, toString

Method Detail

isInitialized

boolean isInitialized()

Returns:

true if initialized, i.e. a GLContext is bound and made current once, otherwise false.

resetSize

void resetSize(GL gl)
               throws GLException

Notify this instance about upstream size change to reconfigure the FBObject.

Parameters:

gl - GL context object bound to this drawable, will be made current during operation. A prev. current context will be make current after operation.

Throws:

GLException - if resize operation failed

getTextureUnit

int getTextureUnit()

Returns:

the used texture unit

setTextureUnit

void setTextureUnit(int unit)

Parameters:

unit - the texture unit to be used

setNumSamples

void setNumSamples(GL gl,
                 int newSamples)
                   throws GLException

Set the number of sample buffers if using MSAA

Parameters:

gl - GL context object bound to this drawable, will be made current during operation. A prev. current context will be make current after operation.

newSamples - new sample size

Throws:

GLException - if resetting the FBO failed

getNumSamples

int getNumSamples()

Returns:

the number of sample buffers if using MSAA, otherwise 0

setNumBuffers

int setNumBuffers(int bufferCount)
                  throws GLException

Sets the number of buffers (FBO) being used if using double buffering.

If double buffering is not chosen, this is a NOP.

Must be called before initialization, otherwise an exception is thrown.

Returns:

the new number of buffers (FBO) used, maybe different than the requested bufferCount (see above)

Throws:

GLException - if already initialized, see isInitialized().

getNumBuffers

int getNumBuffers()

Returns:

the number of buffers (FBO) being used. 1 if not using double buffering, otherwise ≥ 2, depending on setNumBuffers(int).

getFBObject

FBObject getFBObject(int bufferName)
                     throws IllegalArgumentException

If MSAA is being used and GL.GL_FRONT is requested, the internal FBObject sample sink is being returned.

Parameters:

bufferName - GL.GL_FRONT and GL.GL_BACK are valid buffer names

Returns:

the named FBObject

Throws:

IllegalArgumentException - if an illegal buffer name is being used

getTextureBuffer

FBObject.TextureAttachment getTextureBuffer(int bufferName)
                                            throws IllegalArgumentException

Returns the named texture buffer.

If MSAA is being used, only the GL.GL_FRONT buffer is accessible and an exception is being thrown if GL.GL_BACK is being requested.

Parameters:

bufferName - GL.GL_FRONT and GL.GL_BACK are valid buffer names

Returns:

the named FBObject.TextureAttachment

Throws:

IllegalArgumentException - if using MSAA and GL.GL_BACK is requested or an illegal buffer name is being used