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mutter/gl/cogl-fbo.c
Robert Bragg 869a2b4167 [cogl-offscreen] Cleans up the cogl offscreen API and adds documentation 
There were several functions I believe no one is currently using that were
only implemented in the GL backend (cogl_offscreen_blit_region and
cogl_offscreen_blit) that have simply been removed so we have a chance to
think about design later with a real use case.

There was one nonsense function (cogl_offscreen_new_multisample) that
sounded exciting but in all cases it just returned COGL_INVALID_HANDLE
(though at least for GL it checked for multisampling support first!?)
it has also been removed.

The MASK draw buffer type has been removed. If we want to expose color
masking later then I think it at least would be nicer to have the mask be a
property that can be set on any draw buffer.

The cogl_draw_buffer and cogl_{push,pop}_draw_buffer function prototypes
have been moved up into cogl.h since they are for managing global Cogl state
and not for modifying or creating the actual offscreen buffers.

This also documents the API so for example desiphering the semantics of
cogl_offscreen_new_to_texture() should be a bit easier now.
2009-05-02 04:12:26 +01:00

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/*
* 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.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "cogl.h"
#include "cogl-internal.h"
#include "cogl-util.h"
#include "cogl-texture-private.h"
#include "cogl-fbo.h"
#include "cogl-context.h"
#include "cogl-handle.h"
/* Expecting EXT functions not to be defined - redirect to pointers in context */
#define glGenRenderbuffersEXT ctx->pf_glGenRenderbuffersEXT
#define glDeleteRenderbuffersEXT ctx->pf_glDeleteRenderbuffersEXT
#define glBindRenderbufferEXT ctx->pf_glBindRenderbufferEXT
#define glRenderbufferStorageEXT ctx->pf_glRenderbufferStorageEXT
#define glGenFramebuffersEXT ctx->pf_glGenFramebuffersEXT
#define glBindFramebufferEXT ctx->pf_glBindFramebufferEXT
#define glFramebufferTexture2DEXT ctx->pf_glFramebufferTexture2DEXT
#define glFramebufferRenderbufferEXT ctx->pf_glFramebufferRenderbufferEXT
#define glCheckFramebufferStatusEXT ctx->pf_glCheckFramebufferStatusEXT
#define glDeleteFramebuffersEXT ctx->pf_glDeleteFramebuffersEXT
#define glBlitFramebufferEXT ctx->pf_glBlitFramebufferEXT
#define glRenderbufferStorageMultisampleEXT ctx->pf_glRenderbufferStorageMultisampleEXT
#ifndef GL_READ_FRAMEBUFFER_EXT
#define GL_READ_FRAMEBUFFER_EXT 0x8CA8
#endif
#ifndef GL_DRAW_FRAMEBUFFER_EXT
#define GL_DRAW_FRAMEBUFFER_EXT 0x8CA9
#endif
static void _cogl_offscreen_free (CoglFbo *fbo);
COGL_HANDLE_DEFINE (Fbo, offscreen);
CoglHandle
cogl_offscreen_new_to_texture (CoglHandle texhandle)
{
CoglTexture *tex;
CoglFbo *fbo;
CoglTexSliceSpan *x_span;
CoglTexSliceSpan *y_span;
GLuint tex_gl_handle;
GLuint fbo_gl_handle;
GLuint gl_stencil_handle;
GLenum status;
_COGL_GET_CONTEXT (ctx, COGL_INVALID_HANDLE);
if (!cogl_features_available (COGL_FEATURE_OFFSCREEN))
return COGL_INVALID_HANDLE;
/* Make texhandle is a valid texture object */
if (!cogl_is_texture (texhandle))
return COGL_INVALID_HANDLE;
tex = _cogl_texture_pointer_from_handle (texhandle);
/* The texture must not be sliced */
if (tex->slice_gl_handles == NULL)
return COGL_INVALID_HANDLE;
if (tex->slice_gl_handles->len != 1)
return COGL_INVALID_HANDLE;
/* Pick the single texture slice width, height and GL id */
x_span = &g_array_index (tex->slice_x_spans, CoglTexSliceSpan, 0);
y_span = &g_array_index (tex->slice_y_spans, CoglTexSliceSpan, 0);
tex_gl_handle = g_array_index (tex->slice_gl_handles, GLuint, 0);
/* Create a renderbuffer for stenciling */
GE( glGenRenderbuffersEXT (1, &gl_stencil_handle) );
GE( glBindRenderbufferEXT (GL_RENDERBUFFER_EXT, gl_stencil_handle) );
GE( glRenderbufferStorageEXT (GL_RENDERBUFFER_EXT, GL_STENCIL_INDEX8_EXT,
cogl_texture_get_width (texhandle),
cogl_texture_get_height (texhandle)) );
GE( glBindRenderbufferEXT (GL_RENDERBUFFER_EXT, 0) );
/* Generate framebuffer */
glGenFramebuffersEXT (1, &fbo_gl_handle);
GE( glBindFramebufferEXT (GL_FRAMEBUFFER_EXT, fbo_gl_handle) );
GE( glFramebufferTexture2DEXT (GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
tex->gl_target, tex_gl_handle, 0) );
GE( glFramebufferRenderbufferEXT (GL_FRAMEBUFFER_EXT,
GL_STENCIL_ATTACHMENT_EXT,
GL_RENDERBUFFER_EXT, gl_stencil_handle) );
/* Make sure it's complete */
status = glCheckFramebufferStatusEXT (GL_FRAMEBUFFER_EXT);
if (status != GL_FRAMEBUFFER_COMPLETE_EXT)
{
/* Stencil renderbuffers aren't always supported. Try again
without the stencil buffer */
GE( glFramebufferRenderbufferEXT (GL_FRAMEBUFFER_EXT,
GL_STENCIL_ATTACHMENT_EXT,
GL_RENDERBUFFER_EXT,
0) );
GE( glDeleteRenderbuffersEXT (1, &gl_stencil_handle) );
gl_stencil_handle = 0;
status = glCheckFramebufferStatusEXT (GL_FRAMEBUFFER_EXT);
if (status != GL_FRAMEBUFFER_COMPLETE_EXT)
{
/* Still failing, so give up */
GE( glDeleteFramebuffersEXT (1, &fbo_gl_handle) );
GE( glBindFramebufferEXT (GL_FRAMEBUFFER_EXT, 0) );
return COGL_INVALID_HANDLE;
}
}
GE( glBindFramebufferEXT (GL_FRAMEBUFFER_EXT, 0) );
/* Allocate and init a CoglFbo object (store non-wasted size
for subsequent blits and viewport setup) */
fbo = (CoglFbo*) g_malloc (sizeof (CoglFbo));
fbo->width = x_span->size - x_span->waste;
fbo->height = y_span->size - y_span->waste;
fbo->gl_handle = fbo_gl_handle;
fbo->gl_stencil_handle = gl_stencil_handle;
return _cogl_offscreen_handle_new (fbo);
}
static void
_cogl_offscreen_free (CoglFbo *fbo)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
/* Frees FBO resources but its handle is not
released! Do that separately before this! */
if (fbo->gl_stencil_handle)
GE( glDeleteRenderbuffersEXT (1, &fbo->gl_stencil_handle) );
GE( glDeleteFramebuffersEXT (1, &fbo->gl_handle) );
g_free (fbo);
}
void
cogl_set_draw_buffer (CoglBufferTarget target, CoglHandle offscreen)
{
CoglFbo *fbo = NULL;
CoglDrawBufferState *draw_buffer;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
g_assert (ctx->draw_buffer_stack != NULL);
draw_buffer = ctx->draw_buffer_stack->data;
if (target == COGL_OFFSCREEN_BUFFER)
{
/* Make sure it is a valid fbo handle */
if (!cogl_is_offscreen (offscreen))
return;
fbo = _cogl_offscreen_pointer_from_handle (offscreen);
/* Check current draw buffer target */
if (draw_buffer->target != COGL_OFFSCREEN_BUFFER)
{
/* Push the viewport and matrix setup if redirecting
from a non-screen buffer */
GE( glPushAttrib (GL_VIEWPORT_BIT) );
_cogl_set_current_matrix (COGL_MATRIX_PROJECTION);
_cogl_current_matrix_push ();
_cogl_current_matrix_identity ();
_cogl_set_current_matrix (COGL_MATRIX_MODELVIEW);
_cogl_current_matrix_push ();
_cogl_current_matrix_identity ();
}
else
{
/* Override viewport and matrix setup if redirecting
from another offscreen buffer */
_cogl_set_current_matrix (COGL_MATRIX_PROJECTION);
_cogl_current_matrix_identity ();
_cogl_set_current_matrix (COGL_MATRIX_MODELVIEW);
_cogl_current_matrix_identity ();
}
/* Setup new viewport and matrices */
GE( glViewport (0, 0, fbo->width, fbo->height) );
_cogl_current_matrix_translate (-1.0f, -1.0f, 0.0f);
_cogl_current_matrix_scale (2.0f / fbo->width, 2.0f / fbo->height, 1.0f);
/* Bind offscreen framebuffer object */
GE( glBindFramebufferEXT (GL_FRAMEBUFFER_EXT, fbo->gl_handle) );
GE( glColorMask (GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE) );
/* Some implementation require a clear before drawing
to an fbo. Luckily it is affected by scissor test. */
/* FIXME: test where exactly this is needed end whether
a glClear with 0 argument is enough */
GE( glPushAttrib (GL_SCISSOR_BIT) );
GE( glScissor (0,0,0,0) );
GE( glEnable (GL_SCISSOR_TEST) );
GE( glClear (GL_COLOR_BUFFER_BIT) );
GE( glPopAttrib () );
}
else if (target & COGL_WINDOW_BUFFER)
{
/* Check current draw buffer target */
if (draw_buffer->target == COGL_OFFSCREEN_BUFFER)
{
/* Pop viewport and matrices if redirecting back
from an offscreen buffer */
GE( glPopAttrib () );
_cogl_set_current_matrix (COGL_MATRIX_PROJECTION);
_cogl_current_matrix_pop ();
_cogl_set_current_matrix (COGL_MATRIX_MODELVIEW);
_cogl_current_matrix_pop ();
}
/* Bind window framebuffer object */
GE( glBindFramebufferEXT (GL_FRAMEBUFFER_EXT, 0) );
}
/* Store new target */
draw_buffer->target = target;
if (draw_buffer->offscreen != offscreen)
{
if (draw_buffer->offscreen != COGL_INVALID_HANDLE)
cogl_handle_unref (draw_buffer->offscreen);
if (offscreen != COGL_INVALID_HANDLE)
cogl_handle_ref (offscreen);
draw_buffer->offscreen = offscreen;
}
}
void
cogl_push_draw_buffer(void)
{
CoglDrawBufferState *old;
CoglDrawBufferState *draw_buffer;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
g_assert (ctx->draw_buffer_stack != NULL);
old = ctx->draw_buffer_stack->data;
draw_buffer = g_slice_new0 (CoglDrawBufferState);
*draw_buffer = *old;
ctx->draw_buffer_stack =
g_slist_prepend (ctx->draw_buffer_stack, draw_buffer);
}
void
cogl_pop_draw_buffer(void)
{
CoglDrawBufferState *to_pop;
CoglDrawBufferState *to_restore;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
g_assert (ctx->draw_buffer_stack != NULL);
if (ctx->draw_buffer_stack->next == NULL)
{
g_warning ("1 more cogl_pop_draw_buffer() than cogl_push_draw_buffer()");
return;
}
to_pop = ctx->draw_buffer_stack->data;
to_restore = ctx->draw_buffer_stack->next->data;
/* the logic in cogl_set_draw_buffer() only works if
* to_pop is still on top of the stack, because
* cogl_set_draw_buffer() needs to know the previous
* state.
*/
cogl_set_draw_buffer (to_restore->target, to_restore->offscreen);
/* cogl_set_draw_buffer() should have set top of stack
* to to_restore
*/
g_assert (to_restore->target == to_pop->target);
g_assert (to_restore->offscreen == to_pop->offscreen);
g_assert (ctx->draw_buffer_stack->data == to_pop);
ctx->draw_buffer_stack =
g_slist_remove_link (ctx->draw_buffer_stack,
ctx->draw_buffer_stack);
g_slice_free (CoglDrawBufferState, to_pop);
}
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