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Use FBOs and use cogl_read_pixels() to efficiently read partial textures

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* cogl_texture_get_data() is converted to use
   _cogl_texture_foreach_sub_texture_in_region() to iterate
  through the underlying textures.

 * When we need to read only a portion of the underlying
   texture, we set up a FBO and use _cogl_read_pixels()
   to read the portion we need. This is enormously more
   efficient for reading a small portion of a large atlas
   texture.

 * The CoglAtlasTexture, CoglSubTexture, and CoglTexture2dSliced
   implementation of get_texture() are removed.

http://bugzilla.clutter-project.org/show_bug.cgi?id=2414
This commit is contained in:
Owen W. Taylor
2010-11-12 11:02:13 -05:00
committed by Neil Roberts
parent 47ccbf472e
commit cda29a8011
4 changed files with 186 additions and 241 deletions
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191
cogl/cogl-texture.c
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@ -4,6 +4,7 @@
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2007,2008,2009 Intel Corporation.
* Copyright (C) 2010 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
@ -37,6 +38,7 @@
#include "cogl-bitmap-private.h"
#include "cogl-buffer-private.h"
#include "cogl-pixel-array-private.h"
#include "cogl-private.h"
#include "cogl-texture-private.h"
#include "cogl-texture-driver.h"
#include "cogl-texture-2d-sliced-private.h"
@ -1181,6 +1183,169 @@ _cogl_texture_draw_and_read (CoglHandle handle,
return TRUE;
}
static gboolean
get_texture_bits_via_offscreen (CoglHandle texture_handle,
int x,
int y,
int width,
int height,
guint8 *dst_bits,
unsigned int dst_rowstride,
CoglPixelFormat dst_format)
{
CoglFramebuffer *framebuffer;
_COGL_GET_CONTEXT (ctx, FALSE);
if (!cogl_features_available (COGL_FEATURE_OFFSCREEN))
return FALSE;
framebuffer = _cogl_offscreen_new_to_texture_full
(texture_handle,
COGL_OFFSCREEN_DISABLE_DEPTH_AND_STENCIL,
0);
if (framebuffer == NULL)
return FALSE;
cogl_push_framebuffer (framebuffer);
_cogl_read_pixels_with_rowstride (x, y, width, height,
COGL_READ_PIXELS_COLOR_BUFFER,
dst_format, dst_bits, dst_rowstride);
cogl_pop_framebuffer ();
cogl_object_unref (framebuffer);
return TRUE;
}
static gboolean
get_texture_bits_via_copy (CoglHandle texture_handle,
int x,
int y,
int width,
int height,
guint8 *dst_bits,
unsigned int dst_rowstride,
CoglPixelFormat dst_format)
{
CoglTexture *tex = COGL_TEXTURE (texture_handle);
unsigned int full_rowstride;
guint8 *full_bits;
gboolean ret = TRUE;
int bpp;
int full_tex_width, full_tex_height;
full_tex_width = cogl_texture_get_width (texture_handle);
full_tex_height = cogl_texture_get_height (texture_handle);
bpp = _cogl_get_format_bpp (dst_format);
full_rowstride = bpp * full_tex_width;
full_bits = g_malloc (full_rowstride * full_tex_height);
if (tex->vtable->get_data (tex,
dst_format,
full_rowstride,
full_bits))
{
guint8 *dst = dst_bits;
guint8 *src = full_bits + x * bpp + y * full_rowstride;
int i;
for (i = 0; i < height; i++)
{
memcpy (dst, src, bpp * width);
dst += dst_rowstride;
src += full_rowstride;
}
}
else
ret = FALSE;
g_free (full_bits);
return ret;
}
typedef struct
{
int orig_width;
int orig_height;
CoglBitmap *target_bmp;
guint8 *target_bits;
gboolean success;
} CoglTextureGetData;
static void
texture_get_cb (CoglHandle texture_handle,
const float *subtexture_coords,
const float *virtual_coords,
void *user_data)
{
CoglTexture *tex = COGL_TEXTURE (texture_handle);
CoglTextureGetData *tg_data = user_data;
CoglPixelFormat format = _cogl_bitmap_get_format (tg_data->target_bmp);
int bpp = _cogl_get_format_bpp (format);
unsigned int rowstride = _cogl_bitmap_get_rowstride (tg_data->target_bmp);
int subtexture_width = cogl_texture_get_width (texture_handle);
int subtexture_height = cogl_texture_get_height (texture_handle);
int x_in_subtexture = (int) (0.5 + subtexture_width * subtexture_coords[0]);
int y_in_subtexture = (int) (0.5 + subtexture_height * subtexture_coords[1]);
int width = ((int) (0.5 + subtexture_width * subtexture_coords[2])
- x_in_subtexture);
int height = ((int) (0.5 + subtexture_height * subtexture_coords[3])
- y_in_subtexture);
int x_in_bitmap = (int) (0.5 + tg_data->orig_width * virtual_coords[0]);
int y_in_bitmap = (int) (0.5 + tg_data->orig_height * virtual_coords[1]);
guint8 *dst_bits;
if (!tg_data->success)
return;
dst_bits = tg_data->target_bits + x_in_bitmap * bpp + y_in_bitmap * rowstride;
/* If we can read everything as a single slice, then go ahead and do that
* to avoid allocating an FBO. We'll leave it up to the GL implementation to
* do glGetTexImage as efficiently as possible. (GLES doesn't have that,
* so we'll fall through) */
if (x_in_subtexture == 0 && y_in_subtexture == 0 &&
width == subtexture_width && height == subtexture_height)
{
if (tex->vtable->get_data (tex,
format,
rowstride,
dst_bits))
return;
}
/* Next best option is a FBO and glReadPixels */
if (get_texture_bits_via_offscreen (texture_handle,
x_in_subtexture, y_in_subtexture,
width, height,
dst_bits,
rowstride,
format))
return;
/* Getting ugly: read the entire texture, copy out the part we want */
if (get_texture_bits_via_copy (texture_handle,
x_in_subtexture, y_in_subtexture,
width, height,
dst_bits,
rowstride,
format))
return;
/* No luck, the caller will fall back to the draw-to-backbuffer and
* read implementation */
tg_data->success = FALSE;
}
int
cogl_texture_get_data (CoglHandle handle,
CoglPixelFormat format,
@ -1196,13 +1361,14 @@ cogl_texture_get_data (CoglHandle handle,
GLenum closest_gl_type;
CoglBitmap *target_bmp;
CoglBitmap *new_bmp;
gboolean success;
guint8 *src;
guint8 *dst;
int y;
int tex_width;
int tex_height;
CoglTextureGetData tg_data;
if (!cogl_is_texture (handle))
return 0;
@ -1253,17 +1419,26 @@ cogl_texture_get_data (CoglHandle handle,
NULL);
}
if ((dst = _cogl_bitmap_map (target_bmp, COGL_BUFFER_ACCESS_WRITE,
COGL_BUFFER_MAP_HINT_DISCARD)) == NULL)
tg_data.orig_width = tex_width;
tg_data.orig_height = tex_height;
tg_data.target_bmp = target_bmp;
tg_data.target_bits = _cogl_bitmap_map (target_bmp, COGL_BUFFER_ACCESS_WRITE,
COGL_BUFFER_MAP_HINT_DISCARD);
if (tg_data.target_bits == NULL)
{
cogl_object_unref (target_bmp);
return 0;
}
tg_data.success = TRUE;
success = tex->vtable->get_data (tex,
closest_format,
rowstride,
dst);
/* Iterating through the subtextures allows piecing together
* the data for a sliced texture, and allows us to do the
* read-from-framebuffer logic here in a simple fashion rather than
* passing offsets down through the code. */
_cogl_texture_foreach_sub_texture_in_region (handle,
0, 0, 1, 1,
texture_get_cb,
&tg_data);
_cogl_bitmap_unmap (target_bmp);
@ -1271,7 +1446,7 @@ cogl_texture_get_data (CoglHandle handle,
* to read back the texture data; such as for GLES which doesn't
* support glGetTexImage, so here we fallback to drawing the
* texture and reading the pixels from the framebuffer. */
if (!success)
if (!tg_data.success)
_cogl_texture_draw_and_read (tex, target_bmp,
closest_gl_format,
closest_gl_type);