mutter/gles/cogl-fbo.c

/*
 * Clutter COGL
 *
 * A basic GL/GLES Abstraction/Utility Layer
 *
 * Authored By Matthew Allum  <mallum@openedhand.com>
 *
 * Copyright (C) 2008 OpenedHand
 *
 * 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, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

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

#include "cogl.h"
#include "cogl-internal.h"
#include "cogl-util.h"
#include "cogl-texture-private.h"
#include "cogl-fbo.h"
#include "cogl-context.h"
#include "cogl-handle.h"
#include "cogl-gles2-wrapper.h"

#ifdef HAVE_COGL_GLES2

static void _cogl_offscreen_free (CoglFbo *fbo);

COGL_HANDLE_DEFINE (Fbo, offscreen, fbo_handles);

CoglHandle
cogl_offscreen_new_to_texture (CoglHandle texhandle)
{
  CoglTexture      *tex;
  CoglFbo          *fbo;
  CoglTexSliceSpan *x_span;
  CoglTexSliceSpan *y_span;
  GLuint            tex_gl_handle;
  GLuint            fbo_gl_handle;
  GLuint            gl_stencil_handle;
  GLenum            status;

  _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;

  tex = _cogl_texture_pointer_from_handle (texhandle);

  /* The texture must not be sliced */
  if (tex->slice_gl_handles == NULL)
    return COGL_INVALID_HANDLE;

  if (tex->slice_gl_handles->len != 1)
    return COGL_INVALID_HANDLE;

  /* Pick the single texture slice width, height and GL id */
  x_span = &g_array_index (tex->slice_x_spans, CoglTexSliceSpan, 0);
  y_span = &g_array_index (tex->slice_y_spans, CoglTexSliceSpan, 0);
  tex_gl_handle = g_array_index (tex->slice_gl_handles, GLuint, 0);

  /* Create a renderbuffer for stenciling */
  GE( glGenRenderbuffers (1, &gl_stencil_handle) );
  GE( glBindRenderbuffer (GL_RENDERBUFFER, gl_stencil_handle) );
  GE( glRenderbufferStorage (GL_RENDERBUFFER, GL_STENCIL_INDEX8,
			     cogl_texture_get_width (texhandle),
			     cogl_texture_get_height (texhandle)) );
  GE( glBindRenderbuffer (GL_RENDERBUFFER, 0) );

  /* Generate framebuffer */
  glGenFramebuffers (1, &fbo_gl_handle);
  GE( glBindFramebuffer (GL_FRAMEBUFFER, fbo_gl_handle) );
  GE( glFramebufferTexture2D (GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
			      tex->gl_target, tex_gl_handle, 0) );
  GE( glFramebufferRenderbuffer (GL_FRAMEBUFFER,
				 GL_STENCIL_ATTACHMENT,
				 GL_RENDERBUFFER, gl_stencil_handle) );

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

  if (status != GL_FRAMEBUFFER_COMPLETE)
    {
      /* Stencil renderbuffers aren't always supported. Try again
	 without the stencil buffer */
      GE( glFramebufferRenderbuffer (GL_FRAMEBUFFER,
				     GL_STENCIL_ATTACHMENT,
				     GL_RENDERBUFFER,
				     0) );
      GE( glDeleteRenderbuffers (1, &gl_stencil_handle) );
      gl_stencil_handle = 0;

      status = glCheckFramebufferStatus (GL_FRAMEBUFFER);

      if (status != GL_FRAMEBUFFER_COMPLETE)
	{
	  /* Still failing, so give up */
	  GE( glDeleteFramebuffers (1, &fbo_gl_handle) );
	  GE( glBindFramebuffer (GL_FRAMEBUFFER, 0) );
	  return COGL_INVALID_HANDLE;
	}
    }

  GE( glBindFramebuffer (GL_FRAMEBUFFER, 0) );

  /* Allocate and init a CoglFbo object (store non-wasted size
     for subsequent blits and viewport setup) */
  fbo = (CoglFbo*) g_malloc (sizeof (CoglFbo));
  fbo->ref_count         = 1;
  fbo->width             = x_span->size - x_span->waste;
  fbo->height            = y_span->size - y_span->waste;
  fbo->gl_handle         = fbo_gl_handle;
  fbo->gl_stencil_handle = gl_stencil_handle;

  COGL_HANDLE_DEBUG_NEW (offscreen, fbo);

  return _cogl_offscreen_handle_new (fbo);
}

CoglHandle
cogl_offscreen_new_multisample ()
{
  if (!cogl_features_available (COGL_FEATURE_OFFSCREEN_MULTISAMPLE))
    return COGL_INVALID_HANDLE;

  return COGL_INVALID_HANDLE;
}

static void
_cogl_offscreen_free (CoglFbo *fbo)
{
  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  /* Frees FBO resources but its handle is not
     released! Do that separately before this! */
  if (fbo->gl_stencil_handle)
    GE( glDeleteRenderbuffers (1, &fbo->gl_stencil_handle) );
  GE( glDeleteFramebuffers (1, &fbo->gl_handle) );
  g_free (fbo);
}

void
cogl_offscreen_blit_region (CoglHandle src_buffer,
			    CoglHandle dst_buffer,
			    int src_x,
			    int src_y,
			    int src_w,
			    int src_h,
			    int dst_x,
			    int dst_y,
			    int dst_w,
			    int dst_h)
{
  /* Not supported on GLES */
  return;
}

void
cogl_offscreen_blit (CoglHandle src_buffer,
		     CoglHandle dst_buffer)
{
  /* Not supported on GLES */
  return;
}

void
cogl_draw_buffer (CoglBufferTarget target, CoglHandle offscreen)
{
  CoglFbo *fbo = NULL;

  _COGL_GET_CONTEXT (ctx, NO_RETVAL);

  if (target == COGL_OFFSCREEN_BUFFER)
    {
      GLboolean scissor_enabled;
      GLint scissor_box[4];

      /* Make sure it is a valid fbo handle */
      if (!cogl_is_offscreen (offscreen))
	return;

      fbo = _cogl_offscreen_pointer_from_handle (offscreen);

      /* Check current draw buffer target */
      if (ctx->draw_buffer != COGL_OFFSCREEN_BUFFER)
	{
	  /* Push the viewport and matrix setup if redirecting
             from a non-screen buffer */
	  GE( glGetIntegerv (GL_VIEWPORT, ctx->viewport_store) );

	  GE( glMatrixMode (GL_PROJECTION) );
	  GE( glPushMatrix () );
	  GE( glLoadIdentity () );

	  GE( glMatrixMode (GL_MODELVIEW) );
	  GE( glPushMatrix () );
	  GE( glLoadIdentity () );
	}
      else
	{
	  /* Override viewport and matrix setup if redirecting
             from another offscreen buffer */
	  GE( glMatrixMode (GL_PROJECTION) );
	  GE( glLoadIdentity () );

	  GE( glMatrixMode (GL_MODELVIEW) );
	  GE( glLoadIdentity () );
	}

      /* Setup new viewport and matrices */
      GE( glViewport (0, 0, fbo->width, fbo->height) );
      GE( glTranslatef (-1.0, -1.0, 0) );
      GE( glScalef (((float)(2) /
                                (float)(fbo->width)),
			      ((float)(2) /
                                (float)(fbo->height)),
			      1.0) );

      /* Bind offscreen framebuffer object */
      GE( glBindFramebuffer (GL_FRAMEBUFFER, fbo->gl_handle) );
      GE( glColorMask (GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE) );

      /* Some implementation require a clear before drawing
         to an fbo. Luckily it is affected by scissor test. */
      /* FIXME: test where exactly this is needed end whether
         a glClear with 0 argument is enough */

      scissor_enabled = glIsEnabled (GL_SCISSOR_TEST);
      GE( glGetIntegerv (GL_SCISSOR_BOX, scissor_box) );
      GE( glScissor (0, 0, 0, 0) );
      GE( glEnable (GL_SCISSOR_TEST) );
      GE( glClear (GL_COLOR_BUFFER_BIT) );
      if (!scissor_enabled)
	glDisable (GL_SCISSOR_TEST);
      glScissor (scissor_box[0], scissor_box[1],
		 scissor_box[2], scissor_box[3]);

    }
  else if ((target & COGL_WINDOW_BUFFER) ||
	   (target & COGL_MASK_BUFFER))
    {
      /* Check current draw buffer target */
      if (ctx->draw_buffer == COGL_OFFSCREEN_BUFFER)
	{
	  /* Pop viewport and matrices if redirecting back
             from an offscreen buffer */
	  GE( glViewport (ctx->viewport_store[0], ctx->viewport_store[1],
			  ctx->viewport_store[2], ctx->viewport_store[3]) );

	  GE( glMatrixMode (GL_PROJECTION) );
	  GE( glPopMatrix () );

	  GE( glMatrixMode (GL_MODELVIEW) );
	  GE( glPopMatrix () );
	}

      /* Bind window framebuffer object */
      GE( glBindFramebuffer (GL_FRAMEBUFFER, 0) );


      if (target == COGL_WINDOW_BUFFER)
	{
	  /* Draw to RGB channels */
	  GE( glColorMask (GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE) );
	}
      else if (target == COGL_MASK_BUFFER)
	{
	  /* Draw only to ALPHA channel */
	  GE( glColorMask (GL_FALSE, GL_FALSE, GL_FALSE, GL_TRUE) );
	}
      else
	{
	  /* Draw to all channels */
	  GE( glColorMask (GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE) );
	}
    }

  /* Store new target */
  ctx->draw_buffer = target;
}

#else /* HAVE_COGL_GLES2 */

/* No support on regular OpenGL 1.1 */

gboolean
cogl_is_offscreen (CoglHandle handle)
{
  return FALSE;
}

CoglHandle
cogl_offscreen_new_to_texture (CoglHandle texhandle)
{
  return COGL_INVALID_HANDLE;
}

CoglHandle
cogl_offscreen_new_multisample ()
{
  return COGL_INVALID_HANDLE;
}

CoglHandle
cogl_offscreen_ref (CoglHandle handle)
{
  return COGL_INVALID_HANDLE;
}

void
cogl_offscreen_unref (CoglHandle handle)
{
}

void
cogl_offscreen_blit_region (CoglHandle src_buffer,
			    CoglHandle dst_buffer,
			    int src_x,
			    int src_y,
			    int src_w,
			    int src_h,
			    int dst_x,
			    int dst_y,
			    int dst_w,
			    int dst_h)
{
}

void
cogl_offscreen_blit (CoglHandle src_buffer,
		     CoglHandle dst_buffer)
{
}

void
cogl_draw_buffer (CoglBufferTarget target, CoglHandle offscreen)
{
}

#endif /* HAVE_COGL_GLES2 */