2d610c2300
First a few notes about Cogl coordinate systems: - Cogl defines the window origin, viewport origin and texture coordinates origin to be top left unlike OpenGL which defines them as bottom left. - Cogl defines the modelview and projection identity matrices in exactly the same way as OpenGL. - I.e. we believe that for 2D centric constructs: windows/framebuffers, viewports and textures developers are more used to dealing with a top left origin, but when modeling objects in 3D; an origin at the center with y going up is quite natural. The way Cogl handles textures is by uploading data upside down in OpenGL terms so that bottom left becomes top left. (Note: This also has the benefit that we don't need to flip the data we get from image decoding libraries since they typically also consider top left to be the image origin.) The viewport and window coords are mostly handled with various y = height - y tweaks before we pass y coordinates to OpenGL. Generally speaking though the handling of coordinate spaces in Cogl is a bit fragile. I guess partly because none of it was design to be, it just evolved from how Clutter defines its coordinates without much consideration or testing. I hope to improve this over a number of commits; starting here. This commit deals with the fact that offscreen draw buffers may be bound to textures but we don't "upload" the texture data upside down, and so if you texture from an offscreen draw buffer you need to manually flip the texture coordinates to get it the right way around. We now force offscreen rendering to be flipped upside down by tweaking the projection matrix right before we submit it to OpenGL to scale y by -1. The tweak is entirely hidden from the user such that if you call cogl_get_projection you will not see this scale.
223 lines
6.9 KiB
C
223 lines
6.9 KiB
C
/*
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* Cogl
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*
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* An object oriented GL/GLES Abstraction/Utility Layer
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*
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* Copyright (C) 2007,2008,2009 Intel Corporation.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but 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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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "cogl.h"
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#include "cogl-internal.h"
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#include "cogl-util.h"
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#include "cogl-context.h"
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#include "cogl-journal-private.h"
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#include "cogl-texture-private.h"
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#include "cogl-material-private.h"
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#include "cogl-draw-buffer-private.h"
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#include <string.h>
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extern void
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_cogl_create_context_driver (CoglContext *context);
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static CoglContext *_context = NULL;
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static gboolean gl_is_indirect = FALSE;
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static gboolean
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cogl_create_context (void)
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{
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GLubyte default_texture_data[] = { 0xff, 0xff, 0xff, 0x0 };
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gulong enable_flags = 0;
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CoglHandle window_buffer;
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if (_context != NULL)
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return FALSE;
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/* Allocate context memory */
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_context = (CoglContext*) g_malloc (sizeof (CoglContext));
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/* Init default values */
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_context->feature_flags = 0;
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_context->features_cached = FALSE;
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/* Initialise the driver specific state */
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/* TODO: combine these two into one function */
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_cogl_create_context_driver (_context);
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_cogl_features_init ();
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_context->enable_flags = 0;
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_context->color_alpha = 0;
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_context->enable_backface_culling = FALSE;
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_context->indirect = gl_is_indirect;
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cogl_matrix_init_identity (&_context->identity_matrix);
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cogl_matrix_init_identity (&_context->y_flip_matrix);
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cogl_matrix_scale (&_context->y_flip_matrix, 1, -1, 1);
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_context->flushed_matrix_mode = COGL_MATRIX_MODELVIEW;
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_context->texture_units = NULL;
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_context->default_material = cogl_material_new ();
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_context->source_material = NULL;
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_context->default_gl_texture_2d_tex = COGL_INVALID_HANDLE;
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_context->default_gl_texture_rect_tex = COGL_INVALID_HANDLE;
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_context->journal = g_array_new (FALSE, FALSE, sizeof (CoglJournalEntry));
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_context->logged_vertices = g_array_new (FALSE, FALSE, sizeof (GLfloat));
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_context->current_material = NULL;
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_context->current_material_flags = 0;
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memset (&_context->current_material_flush_options,
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0, sizeof (CoglMaterialFlushOptions));
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_context->current_layers = g_array_new (FALSE, FALSE,
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sizeof (CoglLayerInfo));
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_context->n_texcoord_arrays_enabled = 0;
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_context->draw_buffer_stack = _cogl_create_draw_buffer_stack ();
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window_buffer = _cogl_onscreen_new ();
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/* XXX: When setting up the window buffer, cogl_set_draw_buffer
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* assumes that the handle can be found in ctx->window_buffer */
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_context->window_buffer = window_buffer;
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cogl_set_draw_buffer (COGL_WINDOW_BUFFER, 0/* ignored */);
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_context->dirty_bound_framebuffer = TRUE;
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_context->dirty_viewport = TRUE;
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_context->path_nodes = g_array_new (FALSE, FALSE, sizeof (CoglPathNode));
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_context->last_path = 0;
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_context->stencil_material = cogl_material_new ();
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_context->in_begin_gl_block = FALSE;
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_context->quad_indices_byte = COGL_INVALID_HANDLE;
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_context->quad_indices_short = COGL_INVALID_HANDLE;
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_context->quad_indices_short_len = 0;
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_context->texture_download_material = COGL_INVALID_HANDLE;
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/* Create default textures used for fall backs */
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_context->default_gl_texture_2d_tex =
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cogl_texture_new_from_data (1, /* width */
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1, /* height */
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COGL_TEXTURE_NO_SLICING,
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COGL_PIXEL_FORMAT_RGBA_8888_PRE, /* data format */
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/* internal format */
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COGL_PIXEL_FORMAT_RGBA_8888_PRE,
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0, /* auto calc row stride */
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default_texture_data);
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_context->default_gl_texture_rect_tex =
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cogl_texture_new_from_data (1, /* width */
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1, /* height */
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COGL_TEXTURE_NO_SLICING,
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COGL_PIXEL_FORMAT_RGBA_8888_PRE, /* data format */
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/* internal format */
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COGL_PIXEL_FORMAT_RGBA_8888_PRE,
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0, /* auto calc row stride */
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default_texture_data);
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cogl_set_source (_context->default_material);
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_cogl_material_flush_gl_state (_context->source_material, NULL);
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enable_flags =
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_cogl_material_get_cogl_enable_flags (_context->source_material);
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cogl_enable (enable_flags);
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return TRUE;
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}
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void
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_cogl_destroy_context ()
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{
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if (_context == NULL)
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return;
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_cogl_destroy_texture_units ();
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_cogl_free_draw_buffer_stack (_context->draw_buffer_stack);
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if (_context->path_nodes)
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g_array_free (_context->path_nodes, TRUE);
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if (_context->default_gl_texture_2d_tex)
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cogl_handle_unref (_context->default_gl_texture_2d_tex);
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if (_context->default_gl_texture_rect_tex)
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cogl_handle_unref (_context->default_gl_texture_rect_tex);
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if (_context->default_material)
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cogl_handle_unref (_context->default_material);
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if (_context->journal)
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g_array_free (_context->journal, TRUE);
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if (_context->logged_vertices)
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g_array_free (_context->logged_vertices, TRUE);
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if (_context->current_layers)
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g_array_free (_context->current_layers, TRUE);
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if (_context->quad_indices_byte)
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cogl_handle_unref (_context->quad_indices_byte);
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if (_context->quad_indices_short)
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cogl_handle_unref (_context->quad_indices_short);
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g_free (_context);
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}
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CoglContext *
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_cogl_context_get_default ()
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{
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/* Create if doesn't exist yet */
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if (_context == NULL)
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cogl_create_context ();
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return _context;
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}
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/**
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* _cogl_set_indirect_context:
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* @indirect: TRUE if GL context is indirect
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*
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* Advises COGL that the GL context is indirect (commands are sent
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* over a socket). COGL uses this information to try to avoid
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* round-trips in its use of GL, for example.
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*
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* This function cannot be called "on the fly," only before COGL
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* initializes.
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*/
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void
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_cogl_set_indirect_context (gboolean indirect)
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{
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/* we get called multiple times if someone creates
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* more than the default stage
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*/
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if (_context != NULL)
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{
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if (indirect != _context->indirect)
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g_warning ("Right now all stages will be treated as "
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"either direct or indirect, ignoring attempt "
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"to change to indirect=%d", indirect);
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return;
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}
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gl_is_indirect = indirect;
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}
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