org.lwjgl.opengl

Class GLContext

java.lang.Object

org.lwjgl.opengl.GLContext

public final class GLContext
extends java.lang.Object

Manages GL contexts. Before any rendering is done by a LWJGL system, a call should be made to GLContext.useContext() with a context. This will ensure that GLContext has an accurate reflection of the current context's capabilities and function pointers.

This class is thread-safe in the sense that multiple threads can safely call all public methods. The class is also thread-aware in the sense that it tracks a per-thread current context (including capabilities and function pointers). That way, multiple threads can have multiple contexts current and render to them concurrently.

Version:

$Revision$ $Id$

Author:

elias_naur

Constructor Summary

Constructors

Constructor and Description
GLContext()

Method Summary

Methods

Modifier and Type	Method and Description
static ContextCapabilities	getCapabilities() Get the current capabilities instance.
static void	loadOpenGLLibrary() If the OpenGL reference count is 0, the library is loaded.
static void	unloadOpenGLLibrary() The OpenGL library reference count is decremented, and if it reaches 0, the library is unloaded.
static void	useContext(java.lang.Object context) Makes a GL context the current LWJGL context by loading GL function pointers.
static void	useContext(java.lang.Object context, boolean forwardCompatible) Makes a GL context the current LWJGL context by loading GL function pointers.

Methods inherited from class java.lang.Object

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

Constructor Detail

GLContext

public GLContext()

Method Detail

getCapabilities

public static ContextCapabilities getCapabilities()

Get the current capabilities instance. It contains the flags used to test for support of a particular extension.

Returns:

The current capabilities instance.

useContext

public static void useContext(java.lang.Object context)
                       throws LWJGLException

Makes a GL context the current LWJGL context by loading GL function pointers. The context must be current before a call to this method! Instead it simply ensures that the current context is reflected accurately by GLContext's extension caps and function pointers. Use useContext(null) when no context is active.

If the context is the same as last time, then this is a no-op.

If the context has not been encountered before it will be fully initialized from scratch. Otherwise a cached set of caps and function pointers will be used.

The reference to the context is held in a weak reference; therefore if no strong reference exists to the GL context it will automatically be forgotten by the VM at an indeterminate point in the future, freeing up a little RAM.

Parameters:

context - The context object, which uniquely identifies a GL context. If context is null, the native stubs are unloaded.

Throws:

LWJGLException - if context non-null, and the gl library can't be loaded or the basic GL11 functions can't be loaded

useContext

public static void useContext(java.lang.Object context,
              boolean forwardCompatible)
                       throws LWJGLException

Makes a GL context the current LWJGL context by loading GL function pointers. The context must be current before a call to this method! Instead it simply ensures that the current context is reflected accurately by GLContext's extension caps and function pointers. Use useContext(null) when no context is active.

If the context is the same as last time, then this is a no-op.

If the context has not been encountered before it will be fully initialized from scratch. Otherwise a cached set of caps and function pointers will be used.

The reference to the context is held in a weak reference; therefore if no strong reference exists to the GL context it will automatically be forgotten by the VM at an indeterminate point in the future, freeing up a little RAM.

If forwardCompatible is true, function pointers of deprecated GL11-GL21 functionality will not be loaded. Calling a deprecated function using the specified context will result in an IllegalStateException.

Parameters:

context - The context object, which uniquely identifies a GL context. If context is null, the native stubs are unloaded.

forwardCompatible - If the context is a forward compatible context (does not expose deprecated functionality, see XGL_ARB_create_context)

Throws:

LWJGLException - if context non-null, and the gl library can't be loaded or the basic GL11 functions can't be loaded

loadOpenGLLibrary

public static void loadOpenGLLibrary()
                              throws LWJGLException

If the OpenGL reference count is 0, the library is loaded. The reference count is then incremented.

Throws:

LWJGLException

unloadOpenGLLibrary

public static void unloadOpenGLLibrary()

The OpenGL library reference count is decremented, and if it reaches 0, the library is unloaded.