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gtk2/gdk/gdkglcontext.h

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gdk: Add support for OpenGL This adds the new type GdkGLContext that wraps an OpenGL context for a particular native window. It also adds support for the gdk paint machinery to use OpenGL to draw everything. As soon as anyone creates a GL context for a native window we create a "paint context" for that GdkWindow and switch to using GL for painting it. This commit contains only an implementation for X11 (using GLX). The way painting works is that all client gl contexts draw into offscreen buffers rather than directly to the back buffer, and the way something gets onto the window is by using gdk_cairo_draw_from_gl() to draw part of that buffer onto the draw cairo context. As a fallback (if we're doing redirected drawing or some effect like a cairo_push_group()) we read back the gl buffer into memory and composite using cairo. This means that GL rendering works in all cases, including rendering to a PDF. However, this is not particularly fast. In the *typical* case, where we're drawing directly to the window in the regular paint loop we hit the fast path. The fast path uses opengl to draw the buffer to the window back buffer, either by blitting or texturing. Then we track the region that was drawn, and when the draw ends we paint the normal cairo surface to the window (using texture-from-pixmap in the X11 case, or texture from cairo image otherwise) in the regions where there is no gl painted. There are some complexities wrt layering of gl and cairo areas though: * We track via gdk_window_mark_paint_from_clip() whenever gtk is painting over a region we previously rendered with opengl (flushed_region). This area (needs_blend_region) is blended rather than copied at the end of the frame. * If we're drawing a gl texture with alpha we first copy the current cairo_surface inside the target region to the back buffer before we blend over it. These two operations allow us full stacking of transparent gl and cairo regions.
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/* GDK - The GIMP Drawing Kit
*
* gdkglcontext.h: GL context abstraction
*
* Copyright © 2014 Emmanuele Bassi
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __GDK_GL_CONTEXT_H__
#define __GDK_GL_CONTEXT_H__
#if !defined (__GDK_H_INSIDE__) && !defined (GDK_COMPILATION)
#error "Only <gdk/gdk.h> can be included directly."
#endif
#include <gdk/gdkversionmacros.h>
#include <gdk/gdktypes.h>
G_BEGIN_DECLS
#define GDK_TYPE_GL_CONTEXT (gdk_gl_context_get_type ())
#define GDK_GL_CONTEXT(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), GDK_TYPE_GL_CONTEXT, GdkGLContext))
#define GDK_IS_GL_CONTEXT(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GDK_TYPE_GL_CONTEXT))
#define GDK_GL_ERROR (gdk_gl_error_quark ())
GDK_AVAILABLE_IN_3_16
GQuark gdk_gl_error_quark (void);
GDK_AVAILABLE_IN_3_16
GType gdk_gl_context_get_type (void) G_GNUC_CONST;
GDK_AVAILABLE_IN_3_16
GdkVisual * gdk_gl_context_get_visual (GdkGLContext *context);
GDK_AVAILABLE_IN_3_16
GdkWindow * gdk_gl_context_get_window (GdkGLContext *context);
GDK_AVAILABLE_IN_3_16
gl: Make gdk_gl_context_make_current() return void Its not really reasonable to handle failures to make_current, it basically only happens if you pass invalid arguments to it, and thats not something we trap on similar things on the X drawing side. If GL is not supported that should be handled by the context creation failing, and anything going wrong after that is essentially a critical (or an async X error).
2014-10-09 15:24:21 +00:00
void gdk_gl_context_make_current (GdkGLContext *context);
gdk: Add support for OpenGL This adds the new type GdkGLContext that wraps an OpenGL context for a particular native window. It also adds support for the gdk paint machinery to use OpenGL to draw everything. As soon as anyone creates a GL context for a native window we create a "paint context" for that GdkWindow and switch to using GL for painting it. This commit contains only an implementation for X11 (using GLX). The way painting works is that all client gl contexts draw into offscreen buffers rather than directly to the back buffer, and the way something gets onto the window is by using gdk_cairo_draw_from_gl() to draw part of that buffer onto the draw cairo context. As a fallback (if we're doing redirected drawing or some effect like a cairo_push_group()) we read back the gl buffer into memory and composite using cairo. This means that GL rendering works in all cases, including rendering to a PDF. However, this is not particularly fast. In the *typical* case, where we're drawing directly to the window in the regular paint loop we hit the fast path. The fast path uses opengl to draw the buffer to the window back buffer, either by blitting or texturing. Then we track the region that was drawn, and when the draw ends we paint the normal cairo surface to the window (using texture-from-pixmap in the X11 case, or texture from cairo image otherwise) in the regions where there is no gl painted. There are some complexities wrt layering of gl and cairo areas though: * We track via gdk_window_mark_paint_from_clip() whenever gtk is painting over a region we previously rendered with opengl (flushed_region). This area (needs_blend_region) is blended rather than copied at the end of the frame. * If we're drawing a gl texture with alpha we first copy the current cairo_surface inside the target region to the back buffer before we blend over it. These two operations allow us full stacking of transparent gl and cairo regions.
2014-10-09 08:45:44 +00:00
GDK_AVAILABLE_IN_3_16
GdkGLContext * gdk_gl_context_get_current (void);
GDK_AVAILABLE_IN_3_16
void gdk_gl_context_clear_current (void);
G_END_DECLS
#endif /* __GDK_GL_CONTEXT_H__ */
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