// Tracks glBegin/glEnd calls to determine whether it is legal to
// query Vertex Buffer Object state
private boolean inBeginEndPair;

public GLES2Impl(GLProfile glp, GLContextImpl context) {
  this._context = context; 
  this.bufferSizeTracker  = context.getBufferSizeTracker();
  this.bufferStateTracker = context.getBufferStateTracker();
  this.glStateTracker     = context.getGLStateTracker();
  this.glProfile = glp;
}

public final boolean isGL() {
    return true;
}
  
public final boolean isGL4bc() {
    return false;
}

public final boolean isGL4() {
    return false;
}

public final boolean isGL3bc() {
    return false;
}

public final boolean isGL3() {
    return false;
}

public final boolean isGL2() {
    return false;
}

public final boolean isGLES1() {
    return false;
}

public final boolean isGLES2() {
    return true;
}

public final boolean isGLES() {
    return true;
}

public final boolean isGL2ES1() {
    return false;
}

public final boolean isGL2ES2() {
    return true;
}

public final boolean isGL2GL3() {
    return false;
}

public final boolean hasGLSL() {
    return true;
}

public final GL getGL() throws GLException {
    return this;
}

public final GL4bc getGL4bc() throws GLException {
    throw new GLException("Not a GL4bc implementation");
}

public final GL4 getGL4() throws GLException {
    throw new GLException("Not a GL4 implementation");
}

public final GL3bc getGL3bc() throws GLException {
    throw new GLException("Not a GL3bc implementation");
}

public final GL3 getGL3() throws GLException {
    throw new GLException("Not a GL3 implementation");
}

public final GL2 getGL2() throws GLException {
    throw new GLException("Not a GL2 implementation");
}

public final GLES1 getGLES1() throws GLException {
    throw new GLException("Not a GLES1 implementation");
}

public final GLES2 getGLES2() throws GLException {
    return this;
}

public final GL2ES1 getGL2ES1() throws GLException {
    throw new GLException("Not a GL2ES1 implementation");
}

public final GL2ES2 getGL2ES2() throws GLException {
    return this;
}

public final GL2GL3 getGL2GL3() throws GLException {
    throw new GLException("Not a GL2GL3 implementation");
}

public boolean isFunctionAvailable(String glFunctionName) {
  return _context.isFunctionAvailable(glFunctionName);
}

public boolean isExtensionAvailable(String glExtensionName) {
  return _context.isExtensionAvailable(glExtensionName);
}

public Object getExtension(String extensionName) {
  // At this point we don't expose any extensions using this mechanism
  return null;
}

/** Returns the context this GL object is associated with for better
    error checking by DebugGL. */
public GLContext getContext() {
  return _context;
}

private GLContextImpl _context;

public void setSwapInterval(int interval) {
  _context.setSwapInterval(interval);
}

public int getSwapInterval() {
  return _context.getSwapInterval();
}

public Object getPlatformGLExtensions() {
  return _context.getPlatformGLExtensions();
}

//
// Helpers for ensuring the correct amount of texture data
//

/** Returns the number of bytes required to fill in the appropriate
    texture. This is computed as closely as possible based on the
    pixel pack or unpack parameters. The logic in this routine is
    based on code in the SGI OpenGL sample implementation. */

private int imageSizeInBytes(int format, int type, int w, int h, int d,
                             boolean pack) {
  int elements = 0;
  int esize = 0;
  
  if (w < 0) return 0;
  if (h < 0) return 0;
  if (d < 0) return 0;
  switch (format) {
  case GL_STENCIL_INDEX:
    elements = 1;
    break;
  case GL_ALPHA:
  case GL_LUMINANCE:
  case GL_DEPTH_COMPONENT:
    elements = 1;
    break;
  case GL_LUMINANCE_ALPHA:
    elements = 2;
    break;
  case GL_RGB:
    elements = 3;
    break;
  case GL_RGBA:
    elements = 4;
    break;
  default:
    return 0;
  }
  switch (type) {
  case GL_BYTE:
  case GL_UNSIGNED_BYTE:
    esize = 1;
    break;
  case GL_SHORT:
  case GL_UNSIGNED_SHORT:
    esize = 2;
    break;
  case GL_UNSIGNED_SHORT_5_6_5:
  case GL_UNSIGNED_SHORT_4_4_4_4:
  case GL_UNSIGNED_SHORT_5_5_5_1:
    esize = 2;
    elements = 1;
    break;
  case GL_INT:
  case GL_UNSIGNED_INT:
  case GL_FLOAT:
    esize = 4;
    break;
  default:
    return 0;
  }
  return imageSizeInBytes(elements * esize, w, h, d, pack);
}

private GLBufferSizeTracker  bufferSizeTracker;
private GLBufferStateTracker bufferStateTracker;
private GLStateTracker       glStateTracker;

private boolean bufferObjectExtensionsInitialized = false;
private boolean haveOESFramebufferObject;

private void initBufferObjectExtensionChecks() {
  if (bufferObjectExtensionsInitialized)
    return;
  bufferObjectExtensionsInitialized = true;
  haveOESFramebufferObject  = isExtensionAvailable("GL_OES_framebuffer_object");
}

private boolean checkBufferObject(boolean avail,
                                  boolean enabled,
                                  int state,
                                  String kind, boolean throwException) {
  if (!avail) {
    if (!enabled)
      return true;
    if(throwException) {
        throw new GLException("Required extensions not available to call this function");
    }
    return false;
  }
  int buffer = bufferStateTracker.getBoundBufferObject(state, this);
  if (enabled) {
    if (buffer == 0) {
      if(throwException) {
          throw new GLException(kind + " must be enabled to call this method");
      }
      return false;
    }
  } else {
    if (buffer != 0) {
      if(throwException) {
          throw new GLException(kind + " must be disabled to call this method");
      }
      return false;
    }
  }
  return true;
}  

private boolean checkArrayVBODisabled(boolean throwException) { 
  initBufferObjectExtensionChecks();
  return checkBufferObject(true,
                    false,
                    GL.GL_ARRAY_BUFFER,
                    "array vertex_buffer_object", throwException);
}

private boolean checkArrayVBOEnabled(boolean throwException) { 
  initBufferObjectExtensionChecks();
  return checkBufferObject(true,
                    true,
                    GL.GL_ARRAY_BUFFER,
                    "array vertex_buffer_object", throwException);
}

private boolean checkElementVBODisabled(boolean throwException) { 
  initBufferObjectExtensionChecks();
  return checkBufferObject(true,
                    false,
                    GL.GL_ELEMENT_ARRAY_BUFFER,
                    "element vertex_buffer_object", throwException);
}

private boolean checkElementVBOEnabled(boolean throwException) { 
  initBufferObjectExtensionChecks();
  return checkBufferObject(true,
                    true,
                    GL.GL_ELEMENT_ARRAY_BUFFER,
                    "element vertex_buffer_object", throwException);
}

private boolean checkUnpackPBODisabled(boolean throwException) { 
    // PBO n/a for ES 1.1 or ES 2.0
    return true;
}

private boolean checkUnpackPBOEnabled(boolean throwException) { 
    // PBO n/a for ES 1.1 or ES 2.0
    return false;
}

private boolean checkPackPBODisabled(boolean throwException) { 
    // PBO n/a for ES 1.1 or ES 2.0
    return true;
}

private boolean checkPackPBOEnabled(boolean throwException) { 
    // PBO n/a for ES 1.1 or ES 2.0
    return false;
}

// Attempt to return the same ByteBuffer object from glMapBufferARB if
// the vertex buffer object's base address and size haven't changed
private static class ARBVBOKey {
  private long addr;
  private int  capacity;

  ARBVBOKey(long addr, int capacity) {
    this.addr = addr;
    this.capacity = capacity;
  }

  public int hashCode() {
    return (int) addr;
  }

  public boolean equals(Object o) {
    if ((o == null) || (!(o instanceof ARBVBOKey))) {
      return false;
    }

    ARBVBOKey other = (ARBVBOKey) o;
    return ((addr == other.addr) && (capacity == other.capacity));
  }
}

private Map/*<ARBVBOKey, ByteBuffer>*/ arbVBOCache = new HashMap();

/** Entry point to C language function: <br> <code> LPVOID glMapBuffer(GLenum target, GLenum access); </code>    */
public java.nio.ByteBuffer glMapBuffer(int target, int access) {
  final long __addr_ = ((GLES2ProcAddressTable)_context.getGLProcAddressTable())._addressof_glMapBuffer;
  if (__addr_ == 0) {
    throw new GLException("Method \"glMapBuffer\" not available");
  }
  int sz = bufferSizeTracker.getBufferSize(bufferStateTracker,
                                           target,
                                           this);
  long addr;
  addr = dispatch_glMapBuffer(target, access, __addr_);
  if (addr == 0 || sz == 0) {
    return null;
  }
  ARBVBOKey key = new ARBVBOKey(addr, sz);
  java.nio.ByteBuffer _res = (java.nio.ByteBuffer) arbVBOCache.get(key);
  if (_res == null) {
    _res = newDirectByteBuffer(addr, sz);
    InternalBufferUtil.nativeOrder(_res);
    arbVBOCache.put(key, _res);
  }
  _res.position(0);
  return _res;
}

/** Encapsulates function pointer for OpenGL function <br>: <code> LPVOID glMapBuffer(GLenum target, GLenum access); </code>    */
native private long dispatch_glMapBuffer(int target, int access, long glProcAddress);

native private ByteBuffer newDirectByteBuffer(long addr, int capacity);

public void glClearDepth(double depth) {
    glClearDepthf((float)depth); 
}

public void glDepthRange(double zNear, double zFar) {
    glDepthRangef((float)zNear, (float)zFar); 
}