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cogl-atlas: Try 4 different approaches for migrating textures

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Instead of directly banging GL to migrate textures the atlas now uses
the CoglFramebuffer API. It will use one of four approaches; it can
set up two FBOs and use _cogl_blit_framebuffer to copy between them;
it can use a single target fbo and then render the source texture to
the FBO using a Cogl draw call; it can use a single FBO and call
glCopyTexSubImage2D; or it can fallback to reading all of the texture
data back to system memory and uploading it again with a sub texture
update.

Previously GL calls were used directly because Cogl wasn't able to
create a framebuffer without a stencil and depth buffer. However there
is now an internal version of cogl_offscreen_new_to_texture which
takes a set of flags to disable the two buffers.

The code for blitting has now been moved into a separate file called
cogl-blit.c because it has become quite long and it may be useful
outside of the atlas at some point.

The 4 different methods have a fixed order of preference which is:

* Texture render between two FBOs
* glBlitFramebuffer
* glCopyTexSubImage2D
* glGetTexImage + glTexSubImage2D

Once a method is succesfully used it is tried first for all subsequent
blits. The default default can be overridden by setting the
environment variable COGL_ATLAS_DEFAULT_BLIT_MODE to one of the
following values:

* texture-render
* framebuffer
* copy-tex-sub-image
* get-tex-data
This commit is contained in:
Neil Roberts
2011-01-20 17:45:47 +00:00
parent 5ca053a3c1
commit c8ddb3b55a
6 changed files with 501 additions and 169 deletions
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89
cogl/cogl-blit.h Normal file
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/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2011 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, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifndef __COGL_BLIT_H
#define __COGL_BLIT_H
#include <glib.h>
#include "cogl-handle.h"
/* This structures and functions are used when a series of blits needs
to be performed between two textures. In this case there are
multiple methods we can use, most of which involve transferring
between an FBO bound to the texture. */
typedef struct _CoglBlitData CoglBlitData;
typedef gboolean (* CoglBlitBeginFunc) (CoglBlitData *data);
typedef void (* CoglBlitEndFunc) (CoglBlitData *data);
typedef void (* CoglBlitFunc) (CoglBlitData *data,
unsigned int src_x,
unsigned int src_y,
unsigned int dst_x,
unsigned int dst_y,
unsigned int width,
unsigned int height);
typedef struct
{
const char *name;
CoglBlitBeginFunc begin_func;
CoglBlitFunc blit_func;
CoglBlitEndFunc end_func;
} CoglBlitMode;
struct _CoglBlitData
{
CoglHandle src_tex, dst_tex;
unsigned int src_width;
unsigned int src_height;
const CoglBlitMode *blit_mode;
/* If we're not using an FBO then we g_malloc a buffer and copy the
complete texture data in */
unsigned char *image_data;
CoglPixelFormat format;
int bpp;
};
void
_cogl_blit_begin (CoglBlitData *data,
CoglHandle dst_tex,
CoglHandle src_tex);
void
_cogl_blit (CoglBlitData *data,
unsigned int src_x,
unsigned int src_y,
unsigned int dst_x,
unsigned int dst_y,
unsigned int width,
unsigned int height);
void
_cogl_blit_end (CoglBlitData *data);
#endif /* __COGL_BLIT_H */