mutter/cogl/cogl-framebuffer.c

/*
 * Cogl
 *
 * An object oriented GL/GLES Abstraction/Utility Layer
 *
 * Copyright (C) 2007,2008,2009 Intel Corporation.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
 *
 *
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "cogl.h"
#include "cogl-debug.h"
#include "cogl-internal.h"
#include "cogl-context.h"
#include "cogl-handle.h"
#include "cogl-object-private.h"
#include "cogl-util.h"
#include "cogl-texture-private.h"
#include "cogl-framebuffer-private.h"
#include "cogl-clip-stack.h"
#include "cogl-journal-private.h"

#ifndef HAVE_COGL_GLES2

#define glGenRenderbuffers                ctx->drv.pf_glGenRenderbuffers
#define glDeleteRenderbuffers             ctx->drv.pf_glDeleteRenderbuffers
#define glBindRenderbuffer                ctx->drv.pf_glBindRenderbuffer
#define glRenderbufferStorage             ctx->drv.pf_glRenderbufferStorage
#define glGenFramebuffers                 ctx->drv.pf_glGenFramebuffers
#define glBindFramebuffer                 ctx->drv.pf_glBindFramebuffer
#define glFramebufferTexture2D            ctx->drv.pf_glFramebufferTexture2D
#define glFramebufferRenderbuffer         ctx->drv.pf_glFramebufferRenderbuffer
#define glCheckFramebufferStatus          ctx->drv.pf_glCheckFramebufferStatus
#define glDeleteFramebuffers              ctx->drv.pf_glDeleteFramebuffers
#define glGetFramebufferAttachmentParameteriv \
                                          ctx->drv.pf_glGetFramebufferAttachmentParameteriv

#endif

#ifndef GL_FRAMEBUFFER
#define GL_FRAMEBUFFER		0x8D40
#endif
#ifndef GL_RENDERBUFFER
#define GL_RENDERBUFFER		0x8D41
#endif
#ifndef GL_STENCIL_ATTACHMENT
#define GL_STENCIL_ATTACHMENT	0x8D00
#endif
#ifndef GL_COLOR_ATTACHMENT0
#define GL_COLOR_ATTACHMENT0	0x8CE0
#endif
#ifndef GL_FRAMEBUFFER_COMPLETE
#define GL_FRAMEBUFFER_COMPLETE 0x8CD5
#endif
#ifndef GL_STENCIL_INDEX8
#define GL_STENCIL_INDEX8       0x8D48
#endif
#ifndef GL_DEPTH_STENCIL
#define GL_DEPTH_STENCIL        0x84F9
#endif
#ifndef GL_DEPTH_ATTACHMENT
#define GL_DEPTH_ATTACHMENT     0x8D00
#endif
#ifndef GL_DEPTH_COMPONENT16
#define GL_DEPTH_COMPONENT16    0x81A5
#endif
#ifndef GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE
#define GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE      0x8212
#endif
#ifndef GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE
#define GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE    0x8213
#endif
#ifndef GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE
#define GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE     0x8214
#endif
#ifndef GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE
#define GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE    0x8215
#endif
#ifndef GL_FRAMEBUFFER_ATTCHMENT_DEPTH_SIZE
#define GL_FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE    0x8216
#endif
#ifndef GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE
#define GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE  0x8217
#endif

typedef enum {
  _TRY_DEPTH_STENCIL = 1L<<0,
  _TRY_DEPTH         = 1L<<1,
  _TRY_STENCIL       = 1L<<2
} TryFBOFlags;

static void _cogl_framebuffer_free (CoglFramebuffer *framebuffer);
static void _cogl_onscreen_free (CoglOnscreen *onscreen);
static void _cogl_offscreen_free (CoglOffscreen *offscreen);

COGL_OBJECT_INTERNAL_DEFINE (Onscreen, onscreen);
COGL_OBJECT_DEFINE (Offscreen, offscreen);
COGL_OBJECT_DEFINE_DEPRECATED_REF_COUNTING (offscreen);

/* XXX:
 * The CoglObject macros don't support any form of inheritance, so for
 * now we implement the CoglObject support for the CoglFramebuffer
 * abstract class manually.
 */

gboolean
_cogl_is_framebuffer (void *object)
{
  CoglHandleObject *obj = object;

  if (obj == NULL)
    return FALSE;

  return obj->klass->type == _cogl_handle_onscreen_get_type ()
    || obj->klass->type == _cogl_handle_offscreen_get_type ();
}

static void
_cogl_framebuffer_init (CoglFramebuffer *framebuffer,
                        CoglFramebufferType type,
                        CoglPixelFormat format,
                        int width,
                        int height)
{
  framebuffer->type             = type;
  framebuffer->width            = width;
  framebuffer->height           = height;
  framebuffer->format           = format;
  framebuffer->viewport_x       = 0;
  framebuffer->viewport_y       = 0;
  framebuffer->viewport_width   = width;
  framebuffer->viewport_height  = height;

  framebuffer->modelview_stack  = _cogl_matrix_stack_new ();
  framebuffer->projection_stack = _cogl_matrix_stack_new ();

  framebuffer->dirty_bitmasks   = TRUE;

  /* Initialise the clip stack */
  _cogl_clip_state_init (&framebuffer->clip_state);
}

void
_cogl_framebuffer_free (CoglFramebuffer *framebuffer)
{
  _cogl_clip_state_destroy (&framebuffer->clip_state);

  cogl_object_unref (framebuffer->modelview_stack);
  framebuffer->modelview_stack = NULL;

  cogl_object_unref (framebuffer->projection_stack);
  framebuffer->projection_stack = NULL;
}

int
_cogl_framebuffer_get_width (CoglFramebuffer *framebuffer)
{
  return framebuffer->width;
}

int
_cogl_framebuffer_get_height (CoglFramebuffer *framebuffer)
{
  return framebuffer->height;
}

CoglClipState *
_cogl_framebuffer_get_clip_state (CoglFramebuffer *framebuffer)
{
  return &framebuffer->clip_state;
}

void
_cogl_framebuffer_set_viewport (CoglFramebuffer *framebuffer,
                                int x,
                                int y,
                                int width,
                                int height)
{
  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  if (framebuffer->viewport_x == x &&
      framebuffer->viewport_y == y &&
      framebuffer->viewport_width == width &&
      framebuffer->viewport_height == height)
    return;

  _cogl_journal_flush ();

  framebuffer->viewport_x = x;
  framebuffer->viewport_y = y;
  framebuffer->viewport_width = width;
  framebuffer->viewport_height = height;

  if (_cogl_get_framebuffer () == framebuffer)
    ctx->dirty_gl_viewport = TRUE;
}

int
_cogl_framebuffer_get_viewport_x (CoglFramebuffer *framebuffer)
{
  return framebuffer->viewport_x;
}

int
_cogl_framebuffer_get_viewport_y (CoglFramebuffer *framebuffer)
{
  return framebuffer->viewport_y;
}

int
_cogl_framebuffer_get_viewport_width (CoglFramebuffer *framebuffer)
{
  return framebuffer->viewport_width;
}

int
_cogl_framebuffer_get_viewport_height (CoglFramebuffer *framebuffer)
{
  return framebuffer->viewport_height;
}

void
_cogl_framebuffer_get_viewport4fv (CoglFramebuffer *framebuffer, int *viewport)
{
  viewport[0] = framebuffer->viewport_x;
  viewport[1] = framebuffer->viewport_y;
  viewport[2] = framebuffer->viewport_width;
  viewport[3] = framebuffer->viewport_height;
}

CoglMatrixStack *
_cogl_framebuffer_get_modelview_stack (CoglFramebuffer *framebuffer)
{
  return framebuffer->modelview_stack;
}

CoglMatrixStack *
_cogl_framebuffer_get_projection_stack (CoglFramebuffer *framebuffer)
{
  return framebuffer->projection_stack;
}

static inline void
_cogl_framebuffer_init_bits (CoglFramebuffer *framebuffer)
{
  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  if (G_LIKELY (!framebuffer->dirty_bitmasks))
    return;

#ifdef HAVE_COGL_GL
  if (cogl_features_available (COGL_FEATURE_OFFSCREEN)
      && framebuffer->type == COGL_FRAMEBUFFER_TYPE_OFFSCREEN)
    {
      GLenum attachment, pname;

      attachment = GL_COLOR_ATTACHMENT0;

      pname = GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE;
      GE( glGetFramebufferAttachmentParameteriv (GL_FRAMEBUFFER,
                                                 attachment,
                                                 pname,
                                                 &framebuffer->red_bits) );

      pname = GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE;
      GE( glGetFramebufferAttachmentParameteriv (GL_FRAMEBUFFER,
                                                 attachment,
                                                 pname,
                                                 &framebuffer->green_bits) );

      pname = GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE;
      GE( glGetFramebufferAttachmentParameteriv (GL_FRAMEBUFFER,
                                                 attachment,
                                                 pname,
                                                 &framebuffer->blue_bits) );

      pname = GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE;
      GE( glGetFramebufferAttachmentParameteriv (GL_FRAMEBUFFER,
                                                 attachment,
                                                 pname,
                                                 &framebuffer->alpha_bits) );
    }
  else
#endif /* HAVE_COGL_GL */
    {
      GE( glGetIntegerv (GL_RED_BITS,   &framebuffer->red_bits)   );
      GE( glGetIntegerv (GL_GREEN_BITS, &framebuffer->green_bits) );
      GE( glGetIntegerv (GL_BLUE_BITS,  &framebuffer->blue_bits)  );
      GE( glGetIntegerv (GL_ALPHA_BITS, &framebuffer->alpha_bits) );
    }


  COGL_NOTE (OFFSCREEN,
             "RGBA Bits for framebuffer[%p, %s]: %d, %d, %d, %d",
             framebuffer,
             framebuffer->type == COGL_FRAMEBUFFER_TYPE_OFFSCREEN
               ? "offscreen"
               : "onscreen",
             framebuffer->red_bits,
             framebuffer->blue_bits,
             framebuffer->green_bits,
             framebuffer->alpha_bits);

  framebuffer->dirty_bitmasks = FALSE;
}

typedef struct
{
  CoglHandle texture;
  unsigned int level;
  unsigned int level_width;
  unsigned int level_height;
} CoglFramebufferTryFBOData;

static gboolean
try_creating_fbo (CoglOffscreen *offscreen,
                  TryFBOFlags flags,
                  CoglFramebufferTryFBOData *data)
{
  GLuint gl_depth_stencil_handle;
  GLuint gl_depth_handle;
  GLuint gl_stencil_handle;
  GLuint tex_gl_handle;
  GLenum tex_gl_target;
  GLuint fbo_gl_handle;
  GLenum status;

  _COGL_GET_CONTEXT (ctx, FALSE);

  if (!cogl_texture_get_gl_texture (data->texture,
                                    &tex_gl_handle, &tex_gl_target))
    return FALSE;

  if (tex_gl_target != GL_TEXTURE_2D
#ifdef HAVE_COGL_GL
      && tex_gl_target != GL_TEXTURE_RECTANGLE_ARB
#endif
      )
    return FALSE;

  /* We are about to generate and bind a new fbo, so we pretend to change framebuffer
   * state so that the old framebuffer will be rebound again before drawing.
   * The framebuffer state can't be changed while their are active entries, so flush
   * first. */
  _cogl_journal_flush ();
  ctx->dirty_bound_framebuffer = 1;

  /* Generate framebuffer */
  glGenFramebuffers (1, &fbo_gl_handle);
  GE (glBindFramebuffer (GL_FRAMEBUFFER, fbo_gl_handle));
  offscreen->fbo_handle = fbo_gl_handle;

  GE (glFramebufferTexture2D (GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                              tex_gl_target, tex_gl_handle, data->level));

  if (flags & _TRY_DEPTH_STENCIL)
    {
      /* Create a renderbuffer for depth and stenciling */
      GE (glGenRenderbuffers (1, &gl_depth_stencil_handle));
      GE (glBindRenderbuffer (GL_RENDERBUFFER, gl_depth_stencil_handle));
      GE (glRenderbufferStorage (GL_RENDERBUFFER, GL_DEPTH_STENCIL,
                                 data->level_width,
                                 data->level_height));
      GE (glBindRenderbuffer (GL_RENDERBUFFER, 0));
      GE (glFramebufferRenderbuffer (GL_FRAMEBUFFER,
                                     GL_STENCIL_ATTACHMENT,
                                     GL_RENDERBUFFER, gl_depth_stencil_handle));
      GE (glFramebufferRenderbuffer (GL_FRAMEBUFFER,
                                     GL_DEPTH_ATTACHMENT,
                                     GL_RENDERBUFFER, gl_depth_stencil_handle));
      offscreen->renderbuffers =
        g_slist_prepend (offscreen->renderbuffers,
                         GUINT_TO_POINTER (gl_depth_stencil_handle));
    }

  if (flags & _TRY_DEPTH)
    {
      GE (glGenRenderbuffers (1, &gl_depth_handle));
      GE (glBindRenderbuffer (GL_RENDERBUFFER, gl_depth_handle));
      /* For now we just ask for GL_DEPTH_COMPONENT16 since this is all that's
       * available under GLES */
      GE (glRenderbufferStorage (GL_RENDERBUFFER, GL_DEPTH_COMPONENT16,
                                 data->level_width,
                                 data->level_height));
      GE (glBindRenderbuffer (GL_RENDERBUFFER, 0));
      GE (glFramebufferRenderbuffer (GL_FRAMEBUFFER,
                                     GL_DEPTH_ATTACHMENT,
                                     GL_RENDERBUFFER, gl_depth_handle));
      offscreen->renderbuffers =
        g_slist_prepend (offscreen->renderbuffers,
                         GUINT_TO_POINTER (gl_depth_handle));
    }

  if (flags & _TRY_STENCIL)
    {
      GE (glGenRenderbuffers (1, &gl_stencil_handle));
      GE (glBindRenderbuffer (GL_RENDERBUFFER, gl_stencil_handle));
      GE (glRenderbufferStorage (GL_RENDERBUFFER, GL_STENCIL_INDEX8,
                                 data->level_width,
                                 data->level_height));
      GE (glBindRenderbuffer (GL_RENDERBUFFER, 0));
      GE (glFramebufferRenderbuffer (GL_FRAMEBUFFER,
                                     GL_STENCIL_ATTACHMENT,
                                     GL_RENDERBUFFER, gl_stencil_handle));
      offscreen->renderbuffers =
        g_slist_prepend (offscreen->renderbuffers,
                         GUINT_TO_POINTER (gl_stencil_handle));
    }

  /* Make sure it's complete */
  status = glCheckFramebufferStatus (GL_FRAMEBUFFER);

  if (status != GL_FRAMEBUFFER_COMPLETE)
    {
      GSList *l;

      GE (glDeleteFramebuffers (1, &fbo_gl_handle));

      for (l = offscreen->renderbuffers; l; l = l->next)
        {
          GLuint renderbuffer = GPOINTER_TO_UINT (l->data);
          GE (glDeleteRenderbuffers (1, &renderbuffer));
        }

      g_slist_free (offscreen->renderbuffers);
      offscreen->renderbuffers = NULL;

      return FALSE;
    }

  return TRUE;
}

CoglHandle
_cogl_offscreen_new_to_texture_full (CoglHandle texhandle,
                                     CoglOffscreenFlags create_flags,
                                     unsigned int level)
{
  CoglOffscreen      *offscreen;
  static TryFBOFlags  flags;
  static gboolean     have_working_flags = FALSE;
  unsigned int        i;
  CoglFramebufferTryFBOData data;
  gboolean            fbo_created;

  _COGL_GET_CONTEXT (ctx, COGL_INVALID_HANDLE);

  if (!cogl_features_available (COGL_FEATURE_OFFSCREEN))
    return COGL_INVALID_HANDLE;

  /* Make texhandle is a valid texture object */
  if (!cogl_is_texture (texhandle))
    return COGL_INVALID_HANDLE;

  /* The texture must not be sliced */
  if (cogl_texture_is_sliced (texhandle))
    return COGL_INVALID_HANDLE;

  data.texture = texhandle;
  data.level = level;

  /* Calculate the size of the texture at this mipmap level to ensure
     that it's a valid level */
  data.level_width = cogl_texture_get_width (texhandle);
  data.level_height = cogl_texture_get_height (texhandle);

  for (i = 0; i < level; i++)
    {
      /* If neither dimension can be further divided then the level is
         invalid */
      if (data.level_width == 1 && data.level_height == 1)
        return COGL_INVALID_HANDLE;

      if (data.level_width > 1)
        data.level_width >>= 1;
      if (data.level_height > 1)
        data.level_height >>= 1;
    }

  /* XXX: The framebuffer_object spec isn't clear in defining whether attaching
   * a texture as a renderbuffer with mipmap filtering enabled while the
   * mipmaps have not been uploaded should result in an incomplete framebuffer
   * object. (different drivers make different decisions)
   *
   * To avoid an error with drivers that do consider this a problem we
   * explicitly set non mipmapped filters here. These will later be reset when
   * the texture is actually used for rendering according to the filters set on
   * the corresponding CoglPipeline.
   */
  _cogl_texture_set_filters (texhandle, GL_NEAREST, GL_NEAREST);

  offscreen = g_new0 (CoglOffscreen, 1);
  offscreen->texture = cogl_handle_ref (texhandle);

  if ((create_flags & COGL_OFFSCREEN_DISABLE_DEPTH_AND_STENCIL))
    fbo_created = try_creating_fbo (offscreen, 0, &data);
  else
    {
      if ((have_working_flags &&
           try_creating_fbo (offscreen, flags, &data)) ||
#ifdef HAVE_COGL_GL
          try_creating_fbo (offscreen, flags = _TRY_DEPTH_STENCIL, &data) ||
#endif
          try_creating_fbo (offscreen, flags = _TRY_DEPTH | _TRY_STENCIL,
                            &data) ||
          try_creating_fbo (offscreen, flags = _TRY_STENCIL, &data) ||
          try_creating_fbo (offscreen, flags = _TRY_DEPTH, &data) ||
          try_creating_fbo (offscreen, flags = 0, &data))
        {
          /* Record that the last set of flags succeeded so that we can
             try that set first next time */
          have_working_flags = TRUE;
          fbo_created = TRUE;
        }
      else
        fbo_created = FALSE;
    }

  if (fbo_created)
    {
      _cogl_framebuffer_init (COGL_FRAMEBUFFER (offscreen),
                              COGL_FRAMEBUFFER_TYPE_OFFSCREEN,
                              cogl_texture_get_format (texhandle),
                              data.level_width,
                              data.level_height);

      return _cogl_offscreen_object_new (offscreen);
    }
  else
    {
      g_free (offscreen);
      /* XXX: This API should probably have been defined to take a GError */
      g_warning ("%s: Failed to create an OpenGL framebuffer", G_STRLOC);
      return COGL_INVALID_HANDLE;
    }
}

CoglHandle
cogl_offscreen_new_to_texture (CoglHandle texhandle)
{
  return _cogl_offscreen_new_to_texture_full (texhandle, 0, 0);
}

static void
_cogl_offscreen_free (CoglOffscreen *offscreen)
{
  GSList *l;

  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  /* Chain up to parent */
  _cogl_framebuffer_free (COGL_FRAMEBUFFER (offscreen));

  for (l = offscreen->renderbuffers; l; l = l->next)
    {
      GLuint renderbuffer = GPOINTER_TO_UINT (l->data);
      GE (glDeleteRenderbuffers (1, &renderbuffer));
    }
  g_slist_free (offscreen->renderbuffers);

  GE (glDeleteFramebuffers (1, &offscreen->fbo_handle));

  if (offscreen->texture != COGL_INVALID_HANDLE)
    cogl_handle_unref (offscreen->texture);

  g_free (offscreen);
}

CoglHandle
_cogl_onscreen_new (void)
{
  CoglOnscreen *onscreen;

  /* XXX: Until we have full winsys support in Cogl then we can't fully
   * implement CoglOnscreen framebuffers, since we can't, e.g. keep track of
   * the window size. */

  /* FIXME: We are assuming onscreen buffers will always be
     premultiplied so we'll set the premult flag on the bitmap
     format. This will usually be correct because the result of the
     default blending operations for Cogl ends up with premultiplied
     data in the framebuffer. However it is possible for the
     framebuffer to be in whatever format depending on what
     CoglPipeline is used to render to it. Eventually we may want to
     add a way for an application to inform Cogl that the framebuffer
     is not premultiplied in case it is being used for some special
     purpose. */

  onscreen = g_new0 (CoglOnscreen, 1);
  _cogl_framebuffer_init (COGL_FRAMEBUFFER (onscreen),
                          COGL_FRAMEBUFFER_TYPE_ONSCREEN,
                          COGL_PIXEL_FORMAT_RGBA_8888_PRE,
                          0xdeadbeef, /* width */
                          0xdeadbeef); /* height */

  return _cogl_onscreen_object_new (onscreen);
}

static void
_cogl_onscreen_free (CoglOnscreen *onscreen)
{
  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  /* Chain up to parent */
  _cogl_framebuffer_free (COGL_FRAMEBUFFER (onscreen));

  g_free (onscreen);
}

void
_cogl_onscreen_clutter_backend_set_size (int width, int height)
{
  CoglFramebuffer *framebuffer;

  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  framebuffer = COGL_FRAMEBUFFER (ctx->window_buffer);

  if (framebuffer->width == width && framebuffer->height == height)
    return;

  framebuffer->width = width;
  framebuffer->height = height;

  /* We'll need to recalculate the GL viewport state derived
   * from the Cogl viewport */
  ctx->dirty_gl_viewport = 1;
}

GSList *
_cogl_create_framebuffer_stack (void)
{
  GSList *stack = NULL;

  return g_slist_prepend (stack, COGL_INVALID_HANDLE);
}

void
_cogl_free_framebuffer_stack (GSList *stack)
{
  GSList *l;

  for (l = stack; l != NULL; l = l->next)
    {
      CoglFramebuffer *framebuffer = COGL_FRAMEBUFFER (l->data);
      if (framebuffer->type == COGL_FRAMEBUFFER_TYPE_OFFSCREEN)
        _cogl_offscreen_free (COGL_OFFSCREEN (framebuffer));
      else
        _cogl_onscreen_free (COGL_ONSCREEN (framebuffer));
    }
  g_slist_free (stack);
}

/* Set the current framebuffer without checking if it's already the
 * current framebuffer. This is used by cogl_pop_framebuffer while
 * the top of the stack is currently not up to date. */
static void
_cogl_set_framebuffer_real (CoglFramebuffer *framebuffer)
{
  CoglFramebuffer **entry;

  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  cogl_flush ();

  entry = (CoglFramebuffer **)&ctx->framebuffer_stack->data;

  ctx->dirty_bound_framebuffer = 1;
  ctx->dirty_gl_viewport = 1;

  if (framebuffer != COGL_INVALID_HANDLE)
    cogl_object_ref (framebuffer);
  if (*entry != COGL_INVALID_HANDLE)
    cogl_object_unref (*entry);

  *entry = framebuffer;

  /* We've effectively just switched the current modelview and
   * projection matrix stacks and clip state so we need to dirty
   * them to ensure they get flushed for the next batch of geometry
   * we flush */
  _cogl_matrix_stack_dirty (framebuffer->modelview_stack);
  _cogl_matrix_stack_dirty (framebuffer->projection_stack);
  _cogl_clip_stack_dirty ();
}

void
cogl_set_framebuffer (CoglFramebuffer *framebuffer)
{
  g_return_if_fail (_cogl_is_framebuffer (framebuffer));

  if (_cogl_get_framebuffer () != framebuffer)
    _cogl_set_framebuffer_real (framebuffer);
}

/* XXX: deprecated API */
void
cogl_set_draw_buffer (CoglBufferTarget target, CoglHandle handle)
{
  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  if (target == COGL_WINDOW_BUFFER)
    handle = ctx->window_buffer;

  cogl_set_framebuffer (handle);
}

CoglFramebuffer *
_cogl_get_framebuffer (void)
{
  _COGL_GET_CONTEXT (ctx, NULL);

  g_assert (ctx->framebuffer_stack);

  return ctx->framebuffer_stack->data;
}

void
cogl_push_framebuffer (CoglFramebuffer *buffer)
{
  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  g_return_if_fail (_cogl_is_framebuffer (buffer));
  g_assert (ctx->framebuffer_stack);

  cogl_flush ();

  ctx->framebuffer_stack =
    g_slist_prepend (ctx->framebuffer_stack, COGL_INVALID_HANDLE);

  cogl_set_framebuffer (buffer);
}

/* XXX: deprecated API */
void
cogl_push_draw_buffer (void)
{
  cogl_push_framebuffer (_cogl_get_framebuffer ());
}

void
cogl_pop_framebuffer (void)
{
  CoglFramebuffer *to_pop;
  CoglFramebuffer *to_restore;

  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  g_assert (ctx->framebuffer_stack != NULL);
  g_assert (ctx->framebuffer_stack->next != NULL);

  to_pop = ctx->framebuffer_stack->data;
  to_restore = ctx->framebuffer_stack->next->data;

  cogl_flush ();

  cogl_object_unref (to_pop);
  ctx->framebuffer_stack =
    g_slist_delete_link (ctx->framebuffer_stack,
                         ctx->framebuffer_stack);

  /* If the framebuffer has changed as a result of popping the top
   * then re-assert the current buffer so as to dirty state as
   * necessary. */
  if (to_pop != to_restore)
    _cogl_set_framebuffer_real (to_restore);
}

/* XXX: deprecated API */
void
cogl_pop_draw_buffer (void)
{
  cogl_pop_framebuffer ();
}

void
_cogl_framebuffer_flush_state (CoglFramebuffer *framebuffer,
                               CoglFramebufferFlushFlags flags)
{
  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  if (cogl_features_available (COGL_FEATURE_OFFSCREEN) &&
      ctx->dirty_bound_framebuffer)
    {
      if (framebuffer->type == COGL_FRAMEBUFFER_TYPE_OFFSCREEN)
        {
          GE (glBindFramebuffer (GL_FRAMEBUFFER,
                                 COGL_OFFSCREEN (framebuffer)->fbo_handle));
        }
      else
        GE (glBindFramebuffer (GL_FRAMEBUFFER, 0));
      ctx->dirty_bound_framebuffer = FALSE;
    }

  if (ctx->dirty_gl_viewport)
    {
      int gl_viewport_y;

      /* Convert the Cogl viewport y offset to an OpenGL viewport y offset
       * NB: OpenGL defines its window and viewport origins to be bottom
       * left, while Cogl defines them to be top left.
       * NB: We render upside down to offscreen framebuffers so we don't
       * need to convert the y offset in this case. */
      if (cogl_is_offscreen (framebuffer))
        gl_viewport_y = framebuffer->viewport_y;
      else
        gl_viewport_y = framebuffer->height -
          (framebuffer->viewport_y + framebuffer->viewport_height);

      COGL_NOTE (OPENGL, "Calling glViewport(%d, %d, %d, %d)",
                 framebuffer->viewport_x,
                 gl_viewport_y,
                 framebuffer->viewport_width,
                 framebuffer->viewport_height);

      GE (glViewport (framebuffer->viewport_x,
                      gl_viewport_y,
                      framebuffer->viewport_width,
                      framebuffer->viewport_height));
      ctx->dirty_gl_viewport = FALSE;
    }

  /* since we might have changed the framebuffer, we should initialize
   * the bits; this is a no-op if they have already been initialized
   */
  _cogl_framebuffer_init_bits (framebuffer);

  /* XXX: Flushing clip state may trash the modelview and projection
   * matrices so we must do it before flushing the matrices...
   */
  if (!(flags & COGL_FRAMEBUFFER_FLUSH_SKIP_CLIP_STATE))
    _cogl_clip_state_flush (&framebuffer->clip_state);

  if (!(flags & COGL_FRAMEBUFFER_FLUSH_SKIP_MODELVIEW))
    _cogl_matrix_stack_flush_to_gl (framebuffer->modelview_stack,
                                    COGL_MATRIX_MODELVIEW);

  _cogl_matrix_stack_flush_to_gl (framebuffer->projection_stack,
                                  COGL_MATRIX_PROJECTION);
}

int
_cogl_framebuffer_get_red_bits (CoglFramebuffer *framebuffer)
{
  _cogl_framebuffer_init_bits (framebuffer);

  return framebuffer->red_bits;
}

int
_cogl_framebuffer_get_green_bits (CoglFramebuffer *framebuffer)
{
  _cogl_framebuffer_init_bits (framebuffer);

  return framebuffer->green_bits;
}

int
_cogl_framebuffer_get_blue_bits (CoglFramebuffer *framebuffer)
{
  _cogl_framebuffer_init_bits (framebuffer);

  return framebuffer->blue_bits;
}

int
_cogl_framebuffer_get_alpha_bits (CoglFramebuffer *framebuffer)
{
  _cogl_framebuffer_init_bits (framebuffer);

  return framebuffer->alpha_bits;
}