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cogl-texture: refuse downloading textures in cogl_texture_get_data() on GLES

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On drivers that do not support glGetTexImage2D (i.e. on GLES),
cogl_texture_get_data() has a "feature" that allows it to download
texture data by rendering the texture on an intermediate framebuffer
object and then reading back the data from there. However, this
feature requires the user to have previously set an "active"
framebuffer object in the context, which makes this very tricky
because it is not clear to the developer that he needs to do that
in order for some code to work on GLES (of course it works on
desktop GL, so nobody notices...) and additionally the code actually
crashes if an active fbo is not set!

This patch basically removes this feature in order to prevent
the crash and is in line with how this code has evolved in cogl-2.0:
https://git.gnome.org/browse/cogl/commit/?id=6d6a277b8e9a63a8268046e5258877ba94a1da5b

https://bugzilla.gnome.org/show_bug.cgi?id=789961
This commit is contained in:
George Kiagiadakis 2017-10-27 16:49:55 +03:00 committed by Mario Sanchez Prada
parent db866eb052
commit d8f2f583e6
1 changed files with 5 additions and 17 deletions
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22
cogl/cogl/cogl-texture.c
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@ -1156,25 +1156,13 @@ cogl_texture_get_data (CoglTexture *texture,
tg_data.success = FALSE;
}
/* XXX: In some cases _cogl_texture_2d_download_from_gl may fail
* 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. */
/* XXX: In some cases this api may fail to read back the texture
* data; such as for GLES which doesn't support glGetTexImage
*/
if (!tg_data.success)
{
if (!_cogl_texture_draw_and_read (texture, target_bmp,
closest_gl_format,
closest_gl_type,
&ignore_error))
{
/* We have no more fallbacks so we just give up and
* hope for the best */
g_warning ("Failed to read texture since draw-and-read "
"fallback failed: %s", ignore_error->message);
cogl_error_free (ignore_error);
cogl_object_unref (target_bmp);
return 0;
}
cogl_object_unref (target_bmp);
return 0;
}
/* Was intermediate used? */