404 lines
17 KiB
Java
404 lines
17 KiB
Java
/*
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* Copyright (c) 2002-2008 LWJGL Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* * Neither the name of 'LWJGL' nor the names of
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* its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package org.lwjgl.opengl;
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import org.lwjgl.LWJGLException;
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import org.lwjgl.LWJGLUtil;
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import org.lwjgl.MemoryUtil;
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import org.lwjgl.Sys;
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import java.lang.reflect.Method;
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import java.nio.ByteBuffer;
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import java.util.*;
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import static org.lwjgl.opengl.GL11.*;
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import static org.lwjgl.opengl.GL30.*;
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import static org.lwjgl.opengl.GL32.*;
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/**
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* <p/>
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* Manages GL contexts. Before any rendering is done by a LWJGL system, a call should be made to GLContext.useContext() with a
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* context. This will ensure that GLContext has an accurate reflection of the current context's capabilities and function
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* pointers.
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* <p/>
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* This class is thread-safe in the sense that multiple threads can safely call all public methods. The class is also
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* thread-aware in the sense that it tracks a per-thread current context (including capabilities and function pointers).
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* That way, multiple threads can have multiple contexts current and render to them concurrently.
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*
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* @author elias_naur <elias_naur@users.sourceforge.net>
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* @version $Revision$
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* $Id$
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*/
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public final class GLContext {
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/** Maps threads to their current context's ContextCapabilities, if any */
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private static final ThreadLocal<ContextCapabilities> current_capabilities = new ThreadLocal<ContextCapabilities>();
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/**
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* The getCapabilities() method is a potential hot spot in any LWJGL application, since
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* it is needed for context capability discovery (e.g. is OpenGL 2.0 supported?), and
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* for the function pointers of gl functions. However, the 'current_capabilities' ThreadLocal
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* is (relatively) expensive to look up, and since most OpenGL applications use are single threaded
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* rendering, the following two is an optimization for this case.
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* <p/>
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* ThreadLocals can be thought of as a mapping between threads and values, so the idea
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* is to use a lock-less cache of mappings between threads and the current ContextCapabilities. The cache
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* could be any size, but in our case, we want a single sized cache for optimal performance
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* in the single threaded case.
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* <p/>
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* 'fast_path_cache' is the most recent ContextCapabilities (potentially null) and its owner. By
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* recent I mean the last thread setting the value in setCapabilities(). When getCapabilities()
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* is called, a check to see if the current is the owner of the ContextCapabilities instance in
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* fast_path_cache. If so, the instance is returned, if not, some thread has since taken ownership
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* of the cache entry and the slower current_capabilities ThreadLocal is queried instead.
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* <p/>
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* No locks are needed in get/setCapabilities, because even though fast_path_cache can be accessed
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* from multiple threads at once, we are guaranteed by the JVM spec that its value is always valid.
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* Furthermore, if the ownership test in getCapabilities() succeeds, the cache entry can only contain
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* the correct ContextCapabilites (that is, the one from getThreadLocalCapabilites()),
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* since no other thread can set the owner to anyone else than itself.
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*/
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private static CapabilitiesCacheEntry fast_path_cache = new CapabilitiesCacheEntry();
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/**
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* Simple lock-free cache of CapabilitesEntryCache to avoid allocating more than one
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* cache entry per thread
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*/
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private static final ThreadLocal<CapabilitiesCacheEntry> thread_cache_entries = new ThreadLocal<CapabilitiesCacheEntry>();
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/**
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* The weak mapping from context Object instances to ContextCapabilities. Used
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* to avoid recreating a ContextCapabilities every time a context is made current.
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*/
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private static final Map<Object, ContextCapabilities> capability_cache = new WeakHashMap<Object, ContextCapabilities>();
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/** Reference count of the native opengl implementation library */
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private static int gl_ref_count;
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private static boolean did_auto_load;
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static {
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Sys.initialize();
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}
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/**
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* Get the current capabilities instance. It contains the flags used
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* to test for support of a particular extension.
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*
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* @return The current capabilities instance.
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*/
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public static ContextCapabilities getCapabilities() {
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ContextCapabilities caps = getCapabilitiesImpl();
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if ( caps == null )
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throw new RuntimeException("No OpenGL context found in the current thread.");
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return caps;
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}
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private static ContextCapabilities getCapabilitiesImpl() {
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CapabilitiesCacheEntry recent_cache_entry = fast_path_cache;
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// Check owner of cache entry
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if ( recent_cache_entry.owner == Thread.currentThread() ) {
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/* The owner ship test succeeded, so the cache must contain the current ContextCapabilities instance
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* assert recent_cache_entry.capabilities == getThreadLocalCapabilities();
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*/
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return recent_cache_entry.capabilities;
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} else // Some other thread has written to the cache since, and we fall back to the slower path
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return getThreadLocalCapabilities();
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}
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/**
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* Returns the capabilities instance associated with the specified context object.
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*
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* @param context the context object
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*
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* @return the capabilities instance
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*/
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static ContextCapabilities getCapabilities(Object context) {
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return capability_cache.get(context);
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}
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private static ContextCapabilities getThreadLocalCapabilities() {
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return current_capabilities.get();
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}
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/**
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* Set the current capabilities instance. It contains the flags used
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* to test for support of a particular extension.
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*
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* @return The current capabilities instance.
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*/
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static void setCapabilities(ContextCapabilities capabilities) {
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current_capabilities.set(capabilities);
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CapabilitiesCacheEntry thread_cache_entry = thread_cache_entries.get();
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if ( thread_cache_entry == null ) {
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thread_cache_entry = new CapabilitiesCacheEntry();
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thread_cache_entries.set(thread_cache_entry);
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}
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thread_cache_entry.owner = Thread.currentThread();
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thread_cache_entry.capabilities = capabilities;
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fast_path_cache = thread_cache_entry;
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}
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/**
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* Helper method to get a pointer to a named function in the OpenGL library
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* with a name dependent on the current platform
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*/
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public static long getPlatformSpecificFunctionAddress(String function_prefix, String[] os_prefixes, String[] os_function_prefixes, String function) {
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String os_name = System.getProperty("os.name");
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for ( int i = 0; i < os_prefixes.length; i++ )
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if ( os_name.startsWith(os_prefixes[i]) ) {
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String platform_function_name = function.replaceFirst(function_prefix, os_function_prefixes[i]);
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long address = getFunctionAddress(platform_function_name);
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return address;
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}
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return 0;
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}
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/**
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* Helper method to get a pointer to a named function with aliases in the OpenGL library.
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*
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* @param aliases the function name aliases.
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*
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* @return the function pointer address
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*/
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public static long getFunctionAddress(String[] aliases) {
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for ( String alias : aliases ) {
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long address = getFunctionAddress(alias);
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if ( address != 0 )
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return address;
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}
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return 0;
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}
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/** Helper method to get a pointer to a named function in the OpenGL library. */
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public static long getFunctionAddress(String name) {
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ByteBuffer buffer = MemoryUtil.encodeASCII(name);
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return ngetFunctionAddress(MemoryUtil.getAddress(buffer));
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}
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private static native long ngetFunctionAddress(long name);
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/**
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* Determine which extensions are available and returns the context profile mask. Helper method to ContextCapabilities.
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*
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* @param supported_extensions the Set to fill with the available extension names
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*
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* @return the context profile mask, will be 0 for any version < 3.2
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*/
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static int getSupportedExtensions(final Set<String> supported_extensions) {
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// Detect OpenGL version first
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final String version = glGetString(GL_VERSION);
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if ( version == null )
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throw new IllegalStateException("glGetString(GL_VERSION) returned null - possibly caused by missing current context.");
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final StringTokenizer version_tokenizer = new StringTokenizer(version, ". ");
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final String major_string = version_tokenizer.nextToken();
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final String minor_string = version_tokenizer.nextToken();
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int majorVersion = 0;
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int minorVersion = 0;
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try {
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majorVersion = Integer.parseInt(major_string);
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minorVersion = Integer.parseInt(minor_string);
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} catch (NumberFormatException e) {
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LWJGLUtil.log("The major and/or minor OpenGL version is malformed: " + e.getMessage());
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}
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final int[][] GL_VERSIONS = {
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{ 1, 2, 3, 4, 5 }, // OpenGL 1
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{ 0, 1 }, // OpenGL 2
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{ 0, 1, 2, 3 }, // OpenGL 3
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{ 0, 1, 2, 3, 4, 5 }, // OpenGL 4
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};
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for ( int major = 1; major <= GL_VERSIONS.length; major++ ) {
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int[] minors = GL_VERSIONS[major - 1];
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for ( int minor : minors ) {
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if ( major < majorVersion || (major == majorVersion && minor <= minorVersion) )
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supported_extensions.add("OpenGL" + Integer.toString(major) + Integer.toString(minor));
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}
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}
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int profileMask = 0;
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if ( majorVersion < 3 ) {
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// Parse EXTENSIONS string
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final String extensions_string = glGetString(GL_EXTENSIONS);
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if ( extensions_string == null )
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throw new IllegalStateException("glGetString(GL_EXTENSIONS) returned null - is there a context current?");
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final StringTokenizer tokenizer = new StringTokenizer(extensions_string);
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while ( tokenizer.hasMoreTokens() )
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supported_extensions.add(tokenizer.nextToken());
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} else {
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// Use forward compatible indexed EXTENSIONS
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final int extensionCount = glGetInteger(GL_NUM_EXTENSIONS);
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for ( int i = 0; i < extensionCount; i++ )
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supported_extensions.add(glGetStringi(GL_EXTENSIONS, i));
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// Get the context profile mask for versions >= 3.2
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if ( 3 < majorVersion || 2 <= minorVersion ) {
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Util.checkGLError(); // Make sure we have no errors up to this point
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try {
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profileMask = glGetInteger(GL_CONTEXT_PROFILE_MASK);
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// Retrieving GL_CONTEXT_PROFILE_MASK may generate an INVALID_OPERATION error on certain implementations, ignore.
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// Happens on pre10.1 ATI drivers, when ContextAttribs.withProfileCompatibility is not used
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Util.checkGLError();
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} catch (OpenGLException e) {
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LWJGLUtil.log("Failed to retrieve CONTEXT_PROFILE_MASK");
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}
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}
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}
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return profileMask;
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}
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/**
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* Helper method to ContextCapabilities. It will try to initialize the native stubs,
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* and remove the given extension name from the extension set if the initialization fails.
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*/
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static void initNativeStubs(final Class<?> extension_class, Set supported_extensions, String ext_name) {
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resetNativeStubs(extension_class);
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if (supported_extensions.contains(ext_name)) {
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try {
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Method init_stubs_method = extension_class.getDeclaredMethod("initNativeStubs");
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init_stubs_method.invoke(null);
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} catch (Exception e) {
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LWJGLUtil.logger().log(() -> "Failed to initialize extension " + extension_class + " - exception", e);
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supported_extensions.remove(ext_name);
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}
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}
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}
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/**
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* Makes a GL context the current LWJGL context by loading GL function pointers. The context must be current before a call to
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* this method! Instead it simply ensures that the current context is reflected accurately by GLContext's extension caps and
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* function pointers. Use useContext(null) when no context is active. <p>If the context is the same as last time, then this is
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* a no-op. <p>If the context has not been encountered before it will be fully initialized from scratch. Otherwise a cached set
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* of caps and function pointers will be used. <p>The reference to the context is held in a weak reference; therefore if no
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* strong reference exists to the GL context it will automatically be forgotten by the VM at an indeterminate point in the
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* future, freeing up a little RAM.
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*
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* @param context The context object, which uniquely identifies a GL context. If context is null, the native stubs are
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* unloaded.
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*
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* @throws LWJGLException if context non-null, and the gl library can't be loaded or the basic GL11 functions can't be loaded
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*/
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public static synchronized void useContext(Object context) throws LWJGLException {
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useContext(context, false);
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}
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/**
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* Makes a GL context the current LWJGL context by loading GL function pointers. The context must be current before a call to
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* this method! Instead it simply ensures that the current context is reflected accurately by GLContext's extension caps and
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* function pointers. Use useContext(null) when no context is active. <p>If the context is the same as last time, then this is
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* a no-op. <p>If the context has not been encountered before it will be fully initialized from scratch. Otherwise a cached set
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* of caps and function pointers will be used. <p>The reference to the context is held in a weak reference; therefore if no
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* strong reference exists to the GL context it will automatically be forgotten by the VM at an indeterminate point in the
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* future, freeing up a little RAM.
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* <p>If forwardCompatible is true, function pointers of deprecated GL11-GL21 functionality will not be loaded. Calling a deprecated
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* function using the specified context will result in an <code>IllegalStateException</code>.
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*
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* @param context The context object, which uniquely identifies a GL context. If context is null, the native stubs are
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* unloaded.
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* @param forwardCompatible If the context is a forward compatible context (does not expose deprecated functionality, see XGL_ARB_create_context)
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*
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* @throws LWJGLException if context non-null, and the gl library can't be loaded or the basic GL11 functions can't be loaded
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*/
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public static synchronized void useContext(Object context, boolean forwardCompatible) throws LWJGLException {
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if ( context == null ) {
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ContextCapabilities.unloadAllStubs();
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setCapabilities(null);
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if ( did_auto_load )
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unloadOpenGLLibrary();
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return;
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}
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if ( gl_ref_count == 0 ) {
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loadOpenGLLibrary();
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did_auto_load = true;
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}
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try {
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ContextCapabilities capabilities = capability_cache.get(context);
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if ( capabilities == null ) {
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/*
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* The capabilities object registers itself as current. This behaviour is caused
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* by a chicken-and-egg situation where the constructor needs to call GL functions
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* as part of its capability discovery, but GL functions cannot be called before
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* a capabilities object has been set.
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*/
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new ContextCapabilities(forwardCompatible);
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capability_cache.put(context, getCapabilities());
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} else
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setCapabilities(capabilities);
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} catch (LWJGLException e) {
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if ( did_auto_load )
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unloadOpenGLLibrary();
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throw e;
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}
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}
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/** If the OpenGL reference count is 0, the library is loaded. The reference count is then incremented. */
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public static synchronized void loadOpenGLLibrary() throws LWJGLException {
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if ( gl_ref_count == 0 )
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nLoadOpenGLLibrary();
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gl_ref_count++;
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}
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private static native void nLoadOpenGLLibrary() throws LWJGLException;
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/** The OpenGL library reference count is decremented, and if it reaches 0, the library is unloaded. */
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public static synchronized void unloadOpenGLLibrary() {
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gl_ref_count--;
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/*
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* Unload the native OpenGL library unless we're on linux, since
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* some drivers (NVIDIA proprietary) crash on exit when unloading the library.
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*/
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if ( gl_ref_count == 0 && LWJGLUtil.getPlatform() != LWJGLUtil.PLATFORM_LINUX )
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nUnloadOpenGLLibrary();
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}
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private static native void nUnloadOpenGLLibrary();
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/** Native method to clear native stub bindings */
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static native void resetNativeStubs(Class clazz);
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private static final class CapabilitiesCacheEntry {
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Thread owner;
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ContextCapabilities capabilities;
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}
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}
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