* * Note that because the enumerated value used for the binding of a * buffer object (e.g. GL_ARRAY_BUFFER) is different than that used to * query the binding using glGetIntegerv (e.g. * GL_ARRAY_BUFFER_BINDING), then in the face of new binding targets * being added to the GL (e.g. GL_TRANSFORM_FEEDBACK_BUFFER_NV) it is * impossible to set up a query of the buffer object currently bound * to a particular state. It turns out that for some uses, such as * finding the size of the currently bound buffer, this doesn't * matter, though of course without knowing the buffer object we can't * re-associate the queried size with the buffer object ID.
* * Because the namespace of buffer objects is the unsigned integers * with 0 reserved by the GL, and because we have to be able to return * both 0 and other integers as valid answers from * getBoundBufferObject(), we need a second query, which is to ask * whether we know the state of the binding for a given target. For * "unknown" targets such as GL_TRANSFORM_FEEDBACK_BUFFER_NV we return * false from this, but we also clear the valid bit and later refresh * the binding state if glPushClientAttrib / glPopClientAttrib are * called, since we don't want the complexity of tracking stacks of * these attributes. * */ public class GLBufferStateTracker { protected static final boolean DEBUG; static { Debug.initSingleton(); DEBUG = Debug.isPropertyDefined("jogl.debug.GLBufferStateTracker", true); } // Maps binding targets to buffer objects. A null value indicates // that the binding is unknown. A zero value indicates that it is // known that no buffer is bound to the target, according to the // OpenGL specifications. // http://www.opengl.org/sdk/docs/man/xhtml/glBindBuffer.xml private IntIntHashMap bindingMap; private int[] bufTmp = new int[1]; public GLBufferStateTracker() { bindingMap = new IntIntHashMap(); bindingMap.setKeyNotFoundValue(0xFFFFFFFF); // Start with known unbound targets for known keys // setBoundBufferObject(GL2GL3.GL_VERTEX_ARRAY_BINDING, 0); // not using default VAO (removed in GL3 core) - only explicit setBoundBufferObject(GL.GL_ARRAY_BUFFER, 0); setBoundBufferObject(GL.GL_ELEMENT_ARRAY_BUFFER, 0); setBoundBufferObject(GL2.GL_PIXEL_PACK_BUFFER, 0); setBoundBufferObject(GL2.GL_PIXEL_UNPACK_BUFFER, 0); setBoundBufferObject(GL4.GL_DRAW_INDIRECT_BUFFER, 0); } public final void setBoundBufferObject(int target, int value) { bindingMap.put(target, value); if (DEBUG) { System.err.println("GLBufferStateTracker.setBoundBufferObject() target 0x" + Integer.toHexString(target) + " -> mapped bound buffer 0x" + Integer.toHexString(value)); // Thread.dumpStack(); } } /** Note: returns an unspecified value if the binding for the specified target (e.g. GL_ARRAY_BUFFER) is currently unknown. You must use isBoundBufferObjectKnown() to see whether the return value is valid. */ public final int getBoundBufferObject(int target, GL caller) { int value = bindingMap.get(target); if (0xFFFFFFFF == value) { // User probably either called glPushClientAttrib / // glPopClientAttrib or is querying an unknown target. See // whether we know how to fetch this state. boolean gotQueryTarget = true; int queryTarget = 0; switch (target) { case GL2GL3.GL_VERTEX_ARRAY_BINDING: queryTarget = GL2GL3.GL_VERTEX_ARRAY_BINDING; break; case GL.GL_ARRAY_BUFFER: queryTarget = GL.GL_ARRAY_BUFFER_BINDING; break; case GL.GL_ELEMENT_ARRAY_BUFFER: queryTarget = GL.GL_ELEMENT_ARRAY_BUFFER_BINDING; break; case GL2.GL_PIXEL_PACK_BUFFER: queryTarget = GL2.GL_PIXEL_PACK_BUFFER_BINDING; break; case GL2.GL_PIXEL_UNPACK_BUFFER: queryTarget = GL2.GL_PIXEL_UNPACK_BUFFER_BINDING; break; case GL4.GL_DRAW_INDIRECT_BUFFER: queryTarget = GL4.GL_DRAW_INDIRECT_BUFFER_BINDING; break; default: gotQueryTarget = false; break; } if (gotQueryTarget) { final int glerrPre = caller.glGetError(); // clear caller.glGetIntegerv(queryTarget, bufTmp, 0); final int glerrPost = caller.glGetError(); // be safe, e.g. GL '3.0 Mesa 8.0.4' may produce an error querying GL_PIXEL_UNPACK_BUFFER_BINDING, ignore value if(GL.GL_NO_ERROR == glerrPost) { value = bufTmp[0]; } else { value = 0; } if (DEBUG) { System.err.println("GLBufferStateTracker.getBoundBufferObject() glerr[pre 0x"+Integer.toHexString(glerrPre)+", post 0x"+Integer.toHexString(glerrPost)+"], [queried value]: target 0x" + Integer.toHexString(target) + " / query 0x"+Integer.toHexString(queryTarget)+ " -> mapped bound buffer 0x" + Integer.toHexString(value)); } setBoundBufferObject(target, value); return value; } return 0; } if (DEBUG) { System.err.println("GLBufferStateTracker.getBoundBufferObject() [mapped value]: target 0x" + Integer.toHexString(target) + " -> mapped bound buffer 0x" + Integer.toHexString(value)); } return value; } /** Clears out the known/unknown state of the various buffer object binding states. These will be refreshed later on an as-needed basis. This is called by the implementations of glPushClientAttrib / glPopClientAttrib. Might want to call this from GLContext.makeCurrent() in the future to possibly increase the robustness of these caches in the face of external native code manipulating OpenGL state. */ public final void clearBufferObjectState() { bindingMap.clear(); if (DEBUG) { System.err.println("GLBufferStateTracker.clearBufferObjectState()"); //Thread.dumpStack(); } } }