mutter/cogl/cogl-draw-buffer-private.h

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[draw-buffers] First pass at overhauling Cogl's framebuffer management Cogl's support for offscreen rendering was originally written just to support the clutter_texture_new_from_actor API and due to lack of documentation and several confusing - non orthogonal - side effects of using the API it wasn't really possible to use directly. This commit does a number of things: - It removes {gl,gles}/cogl-fbo.{c,h} and adds shared cogl-draw-buffer.{c,h} files instead which should be easier to maintain. - internally CoglFbo objects are now called CoglDrawBuffers. A CoglDrawBuffer is an abstract base class that is inherited from to implement CoglOnscreen and CoglOffscreen draw buffers. CoglOffscreen draw buffers will initially be used to support the cogl_offscreen_new_to_texture API, and CoglOnscreen draw buffers will start to be used internally to represent windows as we aim to migrate some of Clutter's backend code to Cogl. - It makes draw buffer objects the owners of the following state: - viewport - projection matrix stack - modelview matrix stack - clip state (This means when you switch between draw buffers you will automatically be switching to their associated viewport, matrix and clip state) Aside from hopefully making cogl_offscreen_new_to_texture be more useful short term by having simpler and well defined semantics for cogl_set_draw_buffer, as mentioned above this is the first step for a couple of other things: - Its a step toward moving ownership for windows down from Clutter backends into Cogl, by (internally at least) introducing the CoglOnscreen draw buffer. Note: the plan is that cogl_set_draw_buffer will accept on or offscreen draw buffer handles, and the "target" argument will become redundant since we will instead query the type of the given draw buffer handle. - Because we have a common type for on and offscreen framebuffers we can provide a unified API for framebuffer management. Things like: - blitting between buffers - managing ancillary buffers (e.g. attaching depth and stencil buffers) - size requisition - clearing
2009-09-25 09:34:34 -04:00
/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2007,2008,2009 Intel Corporation.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifndef __COGL_DRAW_BUFFER_PRIVATE_H
#define __COGL_DRAW_BUFFER_PRIVATE_H
#include "cogl-handle.h"
#include "cogl-matrix-stack.h"
#include "cogl-clip-stack.h"
typedef enum _CoglDrawBufferType {
COGL_DRAW_BUFFER_TYPE_ONSCREEN,
COGL_DRAW_BUFFER_TYPE_OFFSCREEN
} CoglDrawBufferType;
typedef struct
{
CoglHandleObject _parent;
CoglDrawBufferType type;
int width;
int height;
CoglMatrixStack *modelview_stack;
CoglMatrixStack *projection_stack;
int viewport_x;
int viewport_y;
int viewport_width;
int viewport_height;
CoglClipStackState clip_state;
} CoglDrawBuffer;
#define COGL_DRAW_BUFFER(X) ((CoglDrawBuffer *)(X))
typedef struct _CoglDrawBufferStackEntry
{
CoglBufferTarget target;
CoglHandle draw_buffer;
} CoglDrawBufferStackEntry;
typedef struct _CoglOffscreen
{
CoglDrawBuffer _parent;
GLuint fbo_handle;
GLuint gl_stencil_handle;
} CoglOffscreen;
#define COGL_OFFSCREEN(X) ((CoglOffscreen *)(X))
typedef struct _CoglOnscreen
{
CoglDrawBuffer _parent;
} CoglOnscreen;
#define COGL_ONSCREEN(X) ((CoglOnscreen *)(X))
void
_cogl_draw_buffer_state_init (void);
CoglClipStackState *
_cogl_draw_buffer_get_clip_state (CoglHandle handle);
void
_cogl_draw_buffer_set_viewport (CoglHandle handle,
int x,
int y,
int width,
int height);
int
_cogl_draw_buffer_get_viewport_x (CoglHandle handle);
int
_cogl_draw_buffer_get_viewport_y (CoglHandle handle);
int
_cogl_draw_buffer_get_viewport_width (CoglHandle handle);
int
_cogl_draw_buffer_get_viewport_height (CoglHandle handle);
void
_cogl_draw_buffer_get_viewport4fv (CoglHandle handle, int *viewport);
CoglMatrixStack *
_cogl_draw_buffer_get_modelview_stack (CoglHandle handle);
CoglMatrixStack *
_cogl_draw_buffer_get_projection_stack (CoglHandle handle);
typedef enum _CoglDrawBufferFlushFlags
{
/* XXX: When using this, that imples you are going to manually load the
* modelview matrix (via glLoadMatrix). _cogl_matrix_stack_flush_to_gl wont
* be called for draw_buffer->modelview_stack, and the modelview_stack will
* also be marked as dirty. */
COGL_DRAW_BUFFER_FLUSH_SKIP_MODELVIEW = 1L<<0,
} CoglDrawBufferFlushFlags;
void
_cogl_draw_buffer_flush_state (CoglHandle handle,
CoglDrawBufferFlushFlags flags);
CoglHandle
_cogl_onscreen_new (void);
[cogl] Make sure we draw upside down to offscreen draw buffers 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.
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gboolean
cogl_is_offscreen (CoglHandle handle);
[draw-buffers] First pass at overhauling Cogl's framebuffer management Cogl's support for offscreen rendering was originally written just to support the clutter_texture_new_from_actor API and due to lack of documentation and several confusing - non orthogonal - side effects of using the API it wasn't really possible to use directly. This commit does a number of things: - It removes {gl,gles}/cogl-fbo.{c,h} and adds shared cogl-draw-buffer.{c,h} files instead which should be easier to maintain. - internally CoglFbo objects are now called CoglDrawBuffers. A CoglDrawBuffer is an abstract base class that is inherited from to implement CoglOnscreen and CoglOffscreen draw buffers. CoglOffscreen draw buffers will initially be used to support the cogl_offscreen_new_to_texture API, and CoglOnscreen draw buffers will start to be used internally to represent windows as we aim to migrate some of Clutter's backend code to Cogl. - It makes draw buffer objects the owners of the following state: - viewport - projection matrix stack - modelview matrix stack - clip state (This means when you switch between draw buffers you will automatically be switching to their associated viewport, matrix and clip state) Aside from hopefully making cogl_offscreen_new_to_texture be more useful short term by having simpler and well defined semantics for cogl_set_draw_buffer, as mentioned above this is the first step for a couple of other things: - Its a step toward moving ownership for windows down from Clutter backends into Cogl, by (internally at least) introducing the CoglOnscreen draw buffer. Note: the plan is that cogl_set_draw_buffer will accept on or offscreen draw buffer handles, and the "target" argument will become redundant since we will instead query the type of the given draw buffer handle. - Because we have a common type for on and offscreen framebuffers we can provide a unified API for framebuffer management. Things like: - blitting between buffers - managing ancillary buffers (e.g. attaching depth and stencil buffers) - size requisition - clearing
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CoglHandle
_cogl_get_draw_buffer (void);
GSList *
_cogl_create_draw_buffer_stack (void);
void
_cogl_free_draw_buffer_stack (GSList *stack);
#endif /* __COGL_DRAW_BUFFER_PRIVATE_H */