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47af6a0bbf
Add MutterTextureTower, an abstraction for getting a image with the right level of detail for rendering at a particular scale, by manually scaling down by powers of two. This results in much better looking scaled window images when mipmaps can't be used with texture_from_pixmap (which is the typical case for current GL drivers.) When framebuffer objects are available, they are used to do the scaledown using the GPU without having to pull the data back from video memory. A software codepath is also available for the case when FBO's are not present, though performance will suffer https://bugzilla.gnome.org/show_bug.cgi?id=601032
70 lines
2.9 KiB
C
70 lines
2.9 KiB
C
/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
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/*
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* MutterTextureTower
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*
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* Mipmap emulation by creation of scaled down images
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*
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* Copyright (C) 2009 Red Hat, Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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* 02111-1307, USA.
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*/
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#ifndef __MUTTER_TEXTURE_TOWER_H__
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#define __MUTTER_TEXTURE_TOWER_H__
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#include <clutter/clutter.h>
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G_BEGIN_DECLS
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/**
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* SECTION:MutterTextureTower
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* @short_description: mipmap emulation by creation of scaled down images
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*
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* A #MutterTextureTower is used to get good looking scaled down images when
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* we can't use the GL drivers mipmap support. There are two separate reasons
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*
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* - Some cards (including radeon cards <= r5xx) only support
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* TEXTURE_RECTANGLE_ARB and not NPOT textures. Rectangular textures
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* are defined not to support mipmapping.
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* - Even when NPOT textures are available, the combination of NPOT
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* textures, texture_from_pixmap, and mipmapping doesn't typically
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* work, since the X server doesn't allocate pixmaps in the right
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* layout for mipmapping.
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*
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* So, what we do is create the "mipmap" levels ourselves by successive
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* power-of-two scaledowns, and when rendering pick the single texture
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* that best matches the scale we are rendering at. (Since we aren't
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* typically using perspective transforms, we'll frequently have a single
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* scale for the entire texture.)
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*/
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typedef struct _MutterTextureTower MutterTextureTower;
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MutterTextureTower *mutter_texture_tower_new (void);
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void mutter_texture_tower_free (MutterTextureTower *tower);
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void mutter_texture_tower_set_base_texture (MutterTextureTower *tower,
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CoglHandle texture);
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void mutter_texture_tower_update_area (MutterTextureTower *tower,
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int x,
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int y,
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int width,
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int height);
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CoglHandle mutter_texture_tower_get_paint_texture (MutterTextureTower *tower);
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G_BEGIN_DECLS
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#endif /* __MUTTER_TEXTURE_TOWER_H__ */
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