mutter/cogl/cogl-matrix-stack.c

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/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2009,2010 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, see <http://www.gnu.org/licenses/>.
*
*
*
* Authors:
* Havoc Pennington <hp@pobox.com> for litl
[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.
2009-10-22 15:13:01 +00:00
* Robert Bragg <robert@linux.intel.com>
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "cogl.h"
#include "cogl-context.h"
#include "cogl-internal.h"
#include "cogl-matrix-stack.h"
#include "cogl-framebuffer-private.h"
#include "cogl-object-private.h"
typedef struct {
CoglMatrix matrix;
gboolean is_identity;
/* count of pushes with no changes; when a change is
* requested, we create a new state and decrement this
*/
int push_count;
} CoglMatrixState;
/**
* CoglMatrixStack:
*
* Stores a cogl-side matrix stack, which we use as a cache
* so we can get the matrix efficiently when using indirect
* rendering.
*/
struct _CoglMatrixStack
{
CoglObject _parent;
GArray *stack;
/* which state does GL have, NULL if unknown */
CoglMatrixState *flushed_state;
gboolean flushed_identity;
unsigned int age;
};
static void _cogl_matrix_stack_free (CoglMatrixStack *stack);
COGL_OBJECT_INTERNAL_DEFINE (MatrixStack, matrix_stack);
/* XXX: this doesn't initialize the matrix! */
static void
_cogl_matrix_state_init (CoglMatrixState *state)
{
state->push_count = 0;
state->is_identity = FALSE;
}
static CoglMatrixState *
_cogl_matrix_stack_top (CoglMatrixStack *stack)
{
return &g_array_index (stack->stack, CoglMatrixState, stack->stack->len - 1);
}
/* XXX:
* Operations like scale, translate, rotate etc need to have an
* initialized state->matrix to work with, so they will pass
* initialize = TRUE.
*
* _cogl_matrix_stack_load_identity and _cogl_matrix_stack_set on the
* other hand don't so they will pass initialize = FALSE
*
* NB: Identity matrices are represented by setting
* state->is_identity=TRUE in which case state->matrix will be
* uninitialized.
*/
static CoglMatrixState *
_cogl_matrix_stack_top_mutable (CoglMatrixStack *stack,
gboolean initialize)
{
CoglMatrixState *state;
CoglMatrixState *new_top;
state = _cogl_matrix_stack_top (stack);
if (state->push_count == 0)
{
if (state->is_identity && initialize)
cogl_matrix_init_identity (&state->matrix);
return state;
}
state->push_count -= 1;
g_array_set_size (stack->stack, stack->stack->len + 1);
new_top = &g_array_index (stack->stack, CoglMatrixState,
stack->stack->len - 1);
_cogl_matrix_state_init (new_top);
if (initialize)
{
if (state->is_identity)
cogl_matrix_init_identity (&new_top->matrix);
else
new_top->matrix = state->matrix;
if (stack->flushed_state == state)
stack->flushed_state = new_top;
}
return new_top;
}
CoglMatrixStack*
_cogl_matrix_stack_new (void)
{
CoglMatrixStack *stack;
CoglMatrixState *state;
stack = g_slice_new0 (CoglMatrixStack);
stack->stack = g_array_sized_new (FALSE, FALSE,
sizeof (CoglMatrixState), 10);
g_array_set_size (stack->stack, 1);
state = &g_array_index (stack->stack, CoglMatrixState, 0);
_cogl_matrix_state_init (state);
state->is_identity = TRUE;
stack->age = 0;
return _cogl_matrix_stack_object_new (stack);
}
static void
_cogl_matrix_stack_free (CoglMatrixStack *stack)
{
g_array_free (stack->stack, TRUE);
g_slice_free (CoglMatrixStack, stack);
}
void
_cogl_matrix_stack_push (CoglMatrixStack *stack)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top (stack);
/* we lazily create a new stack top if someone changes the matrix
* while push_count > 0
*/
state->push_count += 1;
}
void
_cogl_matrix_stack_pop (CoglMatrixStack *stack)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top (stack);
if (state->push_count > 0)
{
state->push_count -= 1;
}
else
{
if (stack->stack->len == 1)
{
g_warning ("Too many matrix pops");
return;
}
if (stack->flushed_state == state)
{
stack->flushed_state = NULL;
}
stack->age++;
g_array_set_size (stack->stack, stack->stack->len - 1);
}
}
void
_cogl_matrix_stack_load_identity (CoglMatrixStack *stack)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top_mutable (stack, FALSE);
/* NB: Identity matrices are represented by setting
* state->is_identity = TRUE and leaving state->matrix
* uninitialized.
*
* This is done to optimize the heavy usage of
* _cogl_matrix_stack_load_identity by the Cogl Journal.
*/
if (!state->is_identity)
{
state->is_identity = TRUE;
/* mark dirty */
stack->flushed_state = NULL;
stack->age++;
}
}
void
_cogl_matrix_stack_scale (CoglMatrixStack *stack,
float x,
float y,
float z)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top_mutable (stack, TRUE);
cogl_matrix_scale (&state->matrix, x, y, z);
/* mark dirty */
stack->flushed_state = NULL;
state->is_identity = FALSE;
stack->age++;
}
void
_cogl_matrix_stack_translate (CoglMatrixStack *stack,
float x,
float y,
float z)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top_mutable (stack, TRUE);
cogl_matrix_translate (&state->matrix, x, y, z);
/* mark dirty */
stack->flushed_state = NULL;
state->is_identity = FALSE;
stack->age++;
}
void
_cogl_matrix_stack_rotate (CoglMatrixStack *stack,
float angle,
float x,
float y,
float z)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top_mutable (stack, TRUE);
cogl_matrix_rotate (&state->matrix, angle, x, y, z);
/* mark dirty */
stack->flushed_state = NULL;
state->is_identity = FALSE;
stack->age++;
}
void
_cogl_matrix_stack_multiply (CoglMatrixStack *stack,
const CoglMatrix *matrix)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top_mutable (stack, TRUE);
cogl_matrix_multiply (&state->matrix, &state->matrix, matrix);
/* mark dirty */
stack->flushed_state = NULL;
state->is_identity = FALSE;
stack->age++;
}
void
_cogl_matrix_stack_frustum (CoglMatrixStack *stack,
float left,
float right,
float bottom,
float top,
float z_near,
float z_far)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top_mutable (stack, TRUE);
cogl_matrix_frustum (&state->matrix,
left, right, bottom, top,
z_near, z_far);
/* mark dirty */
stack->flushed_state = NULL;
state->is_identity = FALSE;
stack->age++;
}
void
_cogl_matrix_stack_perspective (CoglMatrixStack *stack,
float fov_y,
float aspect,
float z_near,
float z_far)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top_mutable (stack, TRUE);
cogl_matrix_perspective (&state->matrix,
fov_y, aspect, z_near, z_far);
/* mark dirty */
stack->flushed_state = NULL;
state->is_identity = FALSE;
stack->age++;
}
void
_cogl_matrix_stack_ortho (CoglMatrixStack *stack,
float left,
float right,
float bottom,
float top,
float z_near,
float z_far)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top_mutable (stack, TRUE);
cogl_matrix_ortho (&state->matrix,
left, right, bottom, top, z_near, z_far);
/* mark dirty */
stack->flushed_state = NULL;
state->is_identity = FALSE;
stack->age++;
}
gboolean
_cogl_matrix_stack_get_inverse (CoglMatrixStack *stack,
CoglMatrix *inverse)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top_mutable (stack, TRUE);
return cogl_matrix_get_inverse (&state->matrix, inverse);
}
void
_cogl_matrix_stack_get (CoglMatrixStack *stack,
CoglMatrix *matrix)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top (stack);
/* NB: identity matrices are lazily initialized because we can often avoid
* initializing them at all if nothing is pushed on top of them since we
* load them using glLoadIdentity()
*
* The Cogl journal typically loads an identiy matrix because it performs
* software transformations, which is why we have optimized this case.
*/
if (state->is_identity)
cogl_matrix_init_identity (matrix);
else
*matrix = state->matrix;
}
void
_cogl_matrix_stack_set (CoglMatrixStack *stack,
const CoglMatrix *matrix)
{
CoglMatrixState *state;
state = _cogl_matrix_stack_top_mutable (stack, FALSE);
state->matrix = *matrix;
/* mark dirty */
stack->flushed_state = NULL;
state->is_identity = FALSE;
stack->age++;
}
#ifndef HAVE_COGL_GLES2
static void
flush_to_fixed_api_gl (gboolean is_identity,
const CoglMatrix *matrix,
void *user_data)
{
CoglMatrixStack *stack = user_data;
if (is_identity)
{
if (!stack->flushed_identity)
GE (glLoadIdentity ());
stack->flushed_identity = TRUE;
}
else
{
GE (glLoadMatrixf (cogl_matrix_get_array (matrix)) );
stack->flushed_identity = FALSE;
}
}
#endif /* HAVE_COGL_GLES2 */
void
_cogl_matrix_stack_prepare_for_flush (CoglMatrixStack *stack,
CoglMatrixMode mode,
CoglMatrixStackFlushFunc callback,
void *user_data)
{
CoglMatrixState *state;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
state = _cogl_matrix_stack_top (stack);
/* Because Cogl defines texture coordinates to have a top left origin and
* because offscreen framebuffers may be used for rendering to textures we
* always render upside down to offscreen buffers.
*/
if (mode == COGL_MATRIX_PROJECTION &&
cogl_is_offscreen (_cogl_get_draw_buffer ()))
{
CoglMatrix flipped_projection;
CoglMatrix *projection =
state->is_identity ? &ctx->identity_matrix : &state->matrix;
cogl_matrix_multiply (&flipped_projection,
&ctx->y_flip_matrix, projection);
callback (FALSE, &flipped_projection, user_data);
}
else
callback (state->is_identity,
state->is_identity ? &ctx->identity_matrix : &state->matrix,
user_data);
}
void
_cogl_matrix_stack_flush_to_gl (CoglMatrixStack *stack,
CoglMatrixMode mode)
{
CoglMatrixState *state;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
state = _cogl_matrix_stack_top (stack);
#ifdef HAVE_COGL_GLES2
/* Under GLES2 we need to flush the matrices differently because
they are stored in uniforms attached to the program instead of
the global GL context state. At this point we can't be sure that
the right program will be generated so instead we'll just store a
reference to the matrix stack that is intended to be flushed and
update the uniform once the program is ready. */
switch (mode)
{
case COGL_MATRIX_MODELVIEW:
cogl_object_ref (stack);
if (ctx->flushed_modelview_stack)
cogl_object_unref (ctx->flushed_modelview_stack);
ctx->flushed_modelview_stack = stack;
break;
case COGL_MATRIX_PROJECTION:
cogl_object_ref (stack);
if (ctx->flushed_projection_stack)
cogl_object_unref (ctx->flushed_projection_stack);
ctx->flushed_projection_stack = stack;
break;
case COGL_MATRIX_TEXTURE:
/* This shouldn't happen because the texture matrices are
handled by the GLSL pipeline backend */
g_assert_not_reached ();
break;
}
#else /* HAVE_COGL_GLES2 */
if (stack->flushed_state == state)
return;
if (ctx->flushed_matrix_mode != mode)
{
GLenum gl_mode = 0;
switch (mode)
{
case COGL_MATRIX_MODELVIEW:
gl_mode = GL_MODELVIEW;
break;
case COGL_MATRIX_PROJECTION:
gl_mode = GL_PROJECTION;
break;
case COGL_MATRIX_TEXTURE:
gl_mode = GL_TEXTURE;
break;
}
GE (glMatrixMode (gl_mode));
ctx->flushed_matrix_mode = mode;
}
_cogl_matrix_stack_prepare_for_flush (stack,
mode,
flush_to_fixed_api_gl,
stack);
#endif /* HAVE_COGL_GLES2 */
[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.
2009-10-22 15:13:01 +00:00
stack->flushed_state = state;
}
void
_cogl_matrix_stack_dirty (CoglMatrixStack *stack)
{
stack->flushed_state = NULL;
stack->flushed_identity = FALSE;
}
unsigned int
_cogl_matrix_stack_get_age (CoglMatrixStack *stack)
{
return stack->age;
}
gboolean
_cogl_matrix_stack_has_identity_flag (CoglMatrixStack *stack)
{
return _cogl_matrix_stack_top (stack)->is_identity;
}