Minecraft should recognize correct OpenGL version (fixed again)

app/src/main/java/org/lwjgl/opengl/GLContext.java

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