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mutter/cogl/driver/gl/cogl-clip-stack-gl.c
Robert Bragg 8f9151303d pipeline: improve real_blend_enable checks 
Since _cogl_pipeline_update_blend_enable() can sometimes show up quite
high in profiles; instead of calling
_cogl_pipeline_update_blend_enable() whenever we change pipeline state
that may affect blending we now just set a dirty flag and when we flush
a pipeline we check this dirty flag and lazily calculate whether blender
really needs to be enabled if it's set.

Since it turns out we were too optimistic in assuming most GL drivers
would recognize blending with ADD(src,0) is equivalent to disabling
GL_BLEND we now check this case ourselves so we can always explicitly
disable GL_BLEND if we know we don't need blending.

This introduces the idea of an 'unknown_color_alpha' boolean to the
pipeline flush code which is set whenever we can't guarantee that the
color attribute is opaque. For example this is set whenever a user
specifies a color attribute with 4 components when drawing a primitive.
This boolean needs to be cached along with every pipeline because
pipeline::real_blend_enabled depends on this and so we need to also call
_cogl_pipeline_update_blend_enable() if the status of this changes.

Incidentally with this patch we now no longer ever use
_cogl_pipeline_set_blend_enable() internally. For now the internal api
hasn't been removed though since we might want to consider re-purposing
it as a public api since it will now not conflict with our own internal
state tracking and could provide a more convenient way to disable
blending than setting a blend string.

Reviewed-by: Neil Roberts <neil@linux.intel.com>

(cherry picked from commit ab2ae18f3207514c91fa6fd9f2d3f2ed93a86497)
2013-06-06 21:27:09 +01:00

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/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2007,2008,2009,2010,2011,2012 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:
* Neil Roberts <neil@linux.intel.com>
* Robert Bragg <robert@linux.intel.com>
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "cogl-context-private.h"
#include "cogl-util-gl-private.h"
#include "cogl-primitives-private.h"
#include "cogl-pipeline-opengl-private.h"
#include "cogl-path-private.h"
#include "cogl-clip-stack-gl-private.h"
#ifndef GL_CLIP_PLANE0
#define GL_CLIP_PLANE0 0x3000
#define GL_CLIP_PLANE1 0x3001
#define GL_CLIP_PLANE2 0x3002
#define GL_CLIP_PLANE3 0x3003
#define GL_CLIP_PLANE4 0x3004
#define GL_CLIP_PLANE5 0x3005
#endif
static void
project_vertex (const CoglMatrix *modelview_projection,
float *vertex)
{
int i;
cogl_matrix_transform_point (modelview_projection,
&vertex[0], &vertex[1],
&vertex[2], &vertex[3]);
/* Convert from homogenized coordinates */
for (i = 0; i < 4; i++)
vertex[i] /= vertex[3];
}
static void
set_clip_plane (CoglFramebuffer *framebuffer,
int plane_num,
const float *vertex_a,
const float *vertex_b)
{
CoglContext *ctx = framebuffer->context;
float planef[4];
double planed[4];
float angle;
CoglMatrixStack *modelview_stack =
_cogl_framebuffer_get_modelview_stack (framebuffer);
CoglMatrixStack *projection_stack =
_cogl_framebuffer_get_projection_stack (framebuffer);
CoglMatrix inverse_projection;
cogl_matrix_stack_get_inverse (projection_stack, &inverse_projection);
/* Calculate the angle between the axes and the line crossing the
two points */
angle = atan2f (vertex_b[1] - vertex_a[1],
vertex_b[0] - vertex_a[0]) * (180.0/G_PI);
cogl_matrix_stack_push (modelview_stack);
/* Load the inverse of the projection matrix so we can specify the plane
* in screen coordinates */
cogl_matrix_stack_set (modelview_stack, &inverse_projection);
/* Rotate about point a */
cogl_matrix_stack_translate (modelview_stack,
vertex_a[0], vertex_a[1], vertex_a[2]);
/* Rotate the plane by the calculated angle so that it will connect
the two points */
cogl_matrix_stack_rotate (modelview_stack, angle, 0.0f, 0.0f, 1.0f);
cogl_matrix_stack_translate (modelview_stack,
-vertex_a[0], -vertex_a[1], -vertex_a[2]);
/* Clip planes can only be used when a fixed function backend is in
use so we know we can directly push this matrix to the builtin
state */
_cogl_matrix_entry_flush_to_gl_builtins (ctx,
modelview_stack->last_entry,
COGL_MATRIX_MODELVIEW,
framebuffer,
FALSE /* don't disable flip */);
planef[0] = 0;
planef[1] = -1.0;
planef[2] = 0;
planef[3] = vertex_a[1];
switch (ctx->driver)
{
default:
g_assert_not_reached ();
break;
case COGL_DRIVER_GLES1:
GE( ctx, glClipPlanef (plane_num, planef) );
break;
case COGL_DRIVER_GL:
case COGL_DRIVER_GL3:
planed[0] = planef[0];
planed[1] = planef[1];
planed[2] = planef[2];
planed[3] = planef[3];
GE( ctx, glClipPlane (plane_num, planed) );
break;
}
cogl_matrix_stack_pop (modelview_stack);
}
static void
set_clip_planes (CoglFramebuffer *framebuffer,
CoglMatrixEntry *modelview_entry,
float x_1,
float y_1,
float x_2,
float y_2)
{
CoglMatrix modelview_matrix;
CoglMatrixStack *projection_stack =
_cogl_framebuffer_get_projection_stack (framebuffer);
CoglMatrix projection_matrix;
CoglMatrix modelview_projection;
float signed_area;
float vertex_tl[4] = { x_1, y_1, 0, 1.0 };
float vertex_tr[4] = { x_2, y_1, 0, 1.0 };
float vertex_bl[4] = { x_1, y_2, 0, 1.0 };
float vertex_br[4] = { x_2, y_2, 0, 1.0 };
cogl_matrix_stack_get (projection_stack, &projection_matrix);
cogl_matrix_entry_get (modelview_entry, &modelview_matrix);
cogl_matrix_multiply (&modelview_projection,
&projection_matrix,
&modelview_matrix);
project_vertex (&modelview_projection, vertex_tl);
project_vertex (&modelview_projection, vertex_tr);
project_vertex (&modelview_projection, vertex_bl);
project_vertex (&modelview_projection, vertex_br);
/* Calculate the signed area of the polygon formed by the four
vertices so that we can know its orientation */
signed_area = (vertex_tl[0] * (vertex_tr[1] - vertex_bl[1])
+ vertex_tr[0] * (vertex_br[1] - vertex_tl[1])
+ vertex_br[0] * (vertex_bl[1] - vertex_tr[1])
+ vertex_bl[0] * (vertex_tl[1] - vertex_br[1]));
/* Set the clip planes to form lines between all of the vertices
using the same orientation as we calculated */
if (signed_area > 0.0f)
{
/* counter-clockwise */
set_clip_plane (framebuffer, GL_CLIP_PLANE0, vertex_tl, vertex_bl);
set_clip_plane (framebuffer, GL_CLIP_PLANE1, vertex_bl, vertex_br);
set_clip_plane (framebuffer, GL_CLIP_PLANE2, vertex_br, vertex_tr);
set_clip_plane (framebuffer, GL_CLIP_PLANE3, vertex_tr, vertex_tl);
}
else
{
/* clockwise */
set_clip_plane (framebuffer, GL_CLIP_PLANE0, vertex_tl, vertex_tr);
set_clip_plane (framebuffer, GL_CLIP_PLANE1, vertex_tr, vertex_br);
set_clip_plane (framebuffer, GL_CLIP_PLANE2, vertex_br, vertex_bl);
set_clip_plane (framebuffer, GL_CLIP_PLANE3, vertex_bl, vertex_tl);
}
}
static void
add_stencil_clip_rectangle (CoglFramebuffer *framebuffer,
CoglMatrixEntry *modelview_entry,
float x_1,
float y_1,
float x_2,
float y_2,
CoglBool first)
{
CoglMatrixStack *projection_stack =
_cogl_framebuffer_get_projection_stack (framebuffer);
CoglContext *ctx = cogl_framebuffer_get_context (framebuffer);
/* NB: This can be called while flushing the journal so we need
* to be very conservative with what state we change.
*/
_cogl_context_set_current_projection_entry (ctx,
projection_stack->last_entry);
_cogl_context_set_current_modelview_entry (ctx, modelview_entry);
if (first)
{
GE( ctx, glEnable (GL_STENCIL_TEST) );
/* Initially disallow everything */
GE( ctx, glClearStencil (0) );
GE( ctx, glClear (GL_STENCIL_BUFFER_BIT) );
/* Punch out a hole to allow the rectangle */
GE( ctx, glStencilFunc (GL_NEVER, 0x1, 0x1) );
GE( ctx, glStencilOp (GL_REPLACE, GL_REPLACE, GL_REPLACE) );
_cogl_rectangle_immediate (framebuffer,
ctx->stencil_pipeline,
x_1, y_1, x_2, y_2);
}
else
{
/* Add one to every pixel of the stencil buffer in the
rectangle */
GE( ctx, glStencilFunc (GL_NEVER, 0x1, 0x3) );
GE( ctx, glStencilOp (GL_INCR, GL_INCR, GL_INCR) );
_cogl_rectangle_immediate (framebuffer,
ctx->stencil_pipeline,
x_1, y_1, x_2, y_2);
/* Subtract one from all pixels in the stencil buffer so that
only pixels where both the original stencil buffer and the
rectangle are set will be valid */
GE( ctx, glStencilOp (GL_DECR, GL_DECR, GL_DECR) );
_cogl_context_set_current_projection_entry (ctx, &ctx->identity_entry);
_cogl_context_set_current_modelview_entry (ctx, &ctx->identity_entry);
_cogl_rectangle_immediate (framebuffer,
ctx->stencil_pipeline,
-1.0, -1.0, 1.0, 1.0);
}
/* Restore the stencil mode */
GE( ctx, glStencilFunc (GL_EQUAL, 0x1, 0x1) );
GE( ctx, glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP) );
}
typedef void (*SilhouettePaintCallback) (CoglFramebuffer *framebuffer,
CoglPipeline *pipeline,
void *user_data);
static void
add_stencil_clip_silhouette (CoglFramebuffer *framebuffer,
SilhouettePaintCallback silhouette_callback,
CoglMatrixEntry *modelview_entry,
float bounds_x1,
float bounds_y1,
float bounds_x2,
float bounds_y2,
CoglBool merge,
CoglBool need_clear,
void *user_data)
{
CoglMatrixStack *projection_stack =
_cogl_framebuffer_get_projection_stack (framebuffer);
CoglContext *ctx = cogl_framebuffer_get_context (framebuffer);
/* NB: This can be called while flushing the journal so we need
* to be very conservative with what state we change.
*/
_cogl_context_set_current_projection_entry (ctx,
projection_stack->last_entry);
_cogl_context_set_current_modelview_entry (ctx, modelview_entry);
_cogl_pipeline_flush_gl_state (ctx, ctx->stencil_pipeline,
framebuffer, FALSE, FALSE);
GE( ctx, glEnable (GL_STENCIL_TEST) );
GE( ctx, glColorMask (FALSE, FALSE, FALSE, FALSE) );
GE( ctx, glDepthMask (FALSE) );
if (merge)
{
GE (ctx, glStencilMask (2));
GE (ctx, glStencilFunc (GL_LEQUAL, 0x2, 0x6));
}
else
{
/* If we're not using the stencil buffer for clipping then we
don't need to clear the whole stencil buffer, just the area
that will be drawn */
if (need_clear)
/* If this is being called from the clip stack code then it
will have set up a scissor for the minimum bounding box of
all of the clips. That box will likely mean that this
_cogl_clear won't need to clear the entire
buffer. _cogl_framebuffer_clear_without_flush4f is used instead
of cogl_clear because it won't try to flush the journal */
_cogl_framebuffer_clear_without_flush4f (framebuffer,
COGL_BUFFER_BIT_STENCIL,
0, 0, 0, 0);
else
{
/* Just clear the bounding box */
GE( ctx, glStencilMask (~(GLuint) 0) );
GE( ctx, glStencilOp (GL_ZERO, GL_ZERO, GL_ZERO) );
_cogl_rectangle_immediate (framebuffer,
ctx->stencil_pipeline,
bounds_x1, bounds_y1,
bounds_x2, bounds_y2);
}
GE (ctx, glStencilMask (1));
GE (ctx, glStencilFunc (GL_LEQUAL, 0x1, 0x3));
}
GE (ctx, glStencilOp (GL_INVERT, GL_INVERT, GL_INVERT));
silhouette_callback (framebuffer, ctx->stencil_pipeline, user_data);
if (merge)
{
/* Now we have the new stencil buffer in bit 1 and the old
stencil buffer in bit 0 so we need to intersect them */
GE (ctx, glStencilMask (3));
GE (ctx, glStencilFunc (GL_NEVER, 0x2, 0x3));
GE (ctx, glStencilOp (GL_DECR, GL_DECR, GL_DECR));
/* Decrement all of the bits twice so that only pixels where the
value is 3 will remain */
_cogl_context_set_current_projection_entry (ctx, &ctx->identity_entry);
_cogl_context_set_current_modelview_entry (ctx, &ctx->identity_entry);
_cogl_rectangle_immediate (framebuffer, ctx->stencil_pipeline,
-1.0, -1.0, 1.0, 1.0);
_cogl_rectangle_immediate (framebuffer, ctx->stencil_pipeline,
-1.0, -1.0, 1.0, 1.0);
}
GE (ctx, glStencilMask (~(GLuint) 0));
GE (ctx, glDepthMask (TRUE));
GE (ctx, glColorMask (TRUE, TRUE, TRUE, TRUE));
GE (ctx, glStencilFunc (GL_EQUAL, 0x1, 0x1));
GE (ctx, glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP));
}
static void
paint_path_silhouette (CoglFramebuffer *framebuffer,
CoglPipeline *pipeline,
void *user_data)
{
CoglPath *path = user_data;
if (path->data->path_nodes->len >= 3)
_cogl_path_fill_nodes (path,
framebuffer,
pipeline,
COGL_DRAW_SKIP_JOURNAL_FLUSH |
COGL_DRAW_SKIP_PIPELINE_VALIDATION |
COGL_DRAW_SKIP_FRAMEBUFFER_FLUSH);
}
static void
add_stencil_clip_path (CoglFramebuffer *framebuffer,
CoglMatrixEntry *modelview_entry,
CoglPath *path,
CoglBool merge,
CoglBool need_clear)
{
CoglPathData *data = path->data;
add_stencil_clip_silhouette (framebuffer,
paint_path_silhouette,
modelview_entry,
data->path_nodes_min.x,
data->path_nodes_min.y,
data->path_nodes_max.x,
data->path_nodes_max.y,
merge,
need_clear,
path);
}
static void
paint_primitive_silhouette (CoglFramebuffer *framebuffer,
CoglPipeline *pipeline,
void *user_data)
{
_cogl_framebuffer_draw_primitive (framebuffer,
pipeline,
user_data,
COGL_DRAW_SKIP_JOURNAL_FLUSH |
COGL_DRAW_SKIP_PIPELINE_VALIDATION |
COGL_DRAW_SKIP_FRAMEBUFFER_FLUSH |
COGL_DRAW_SKIP_LEGACY_STATE);
}
static void
add_stencil_clip_primitive (CoglFramebuffer *framebuffer,
CoglMatrixEntry *modelview_entry,
CoglPrimitive *primitive,
float bounds_x1,
float bounds_y1,
float bounds_x2,
float bounds_y2,
CoglBool merge,
CoglBool need_clear)
{
add_stencil_clip_silhouette (framebuffer,
paint_primitive_silhouette,
modelview_entry,
bounds_x1,
bounds_y1,
bounds_x2,
bounds_y2,
merge,
need_clear,
primitive);
}
static void
enable_clip_planes (CoglContext *ctx)
{
GE( ctx, glEnable (GL_CLIP_PLANE0) );
GE( ctx, glEnable (GL_CLIP_PLANE1) );
GE( ctx, glEnable (GL_CLIP_PLANE2) );
GE( ctx, glEnable (GL_CLIP_PLANE3) );
}
static void
disable_clip_planes (CoglContext *ctx)
{
GE( ctx, glDisable (GL_CLIP_PLANE3) );
GE( ctx, glDisable (GL_CLIP_PLANE2) );
GE( ctx, glDisable (GL_CLIP_PLANE1) );
GE( ctx, glDisable (GL_CLIP_PLANE0) );
}
void
_cogl_clip_stack_gl_flush (CoglClipStack *stack,
CoglFramebuffer *framebuffer)
{
CoglContext *ctx = framebuffer->context;
int has_clip_planes;
CoglBool using_clip_planes = FALSE;
CoglBool using_stencil_buffer = FALSE;
int scissor_x0;
int scissor_y0;
int scissor_x1;
int scissor_y1;
CoglClipStack *entry;
int scissor_y_start;
/* If we have already flushed this state then we don't need to do
anything */
if (ctx->current_clip_stack_valid)
{
if (ctx->current_clip_stack == stack &&
(ctx->needs_viewport_scissor_workaround == FALSE ||
(framebuffer->viewport_age ==
framebuffer->viewport_age_for_scissor_workaround &&
ctx->viewport_scissor_workaround_framebuffer ==
framebuffer)))
return;
_cogl_clip_stack_unref (ctx->current_clip_stack);
}
ctx->current_clip_stack_valid = TRUE;
ctx->current_clip_stack = _cogl_clip_stack_ref (stack);
has_clip_planes =
ctx->private_feature_flags & COGL_PRIVATE_FEATURE_FOUR_CLIP_PLANES;
if (has_clip_planes)
disable_clip_planes (ctx);
GE( ctx, glDisable (GL_STENCIL_TEST) );
/* If the stack is empty then there's nothing else to do
*
* See comment below about ctx->needs_viewport_scissor_workaround
*/
if (stack == NULL && !ctx->needs_viewport_scissor_workaround)
{
COGL_NOTE (CLIPPING, "Flushed empty clip stack");
ctx->current_clip_stack_uses_stencil = FALSE;
GE (ctx, glDisable (GL_SCISSOR_TEST));
return;
}
/* Calculate the scissor rect first so that if we eventually have to
clear the stencil buffer then the clear will be clipped to the
intersection of all of the bounding boxes. This saves having to
clear the whole stencil buffer */
_cogl_clip_stack_get_bounds (stack,
&scissor_x0, &scissor_y0,
&scissor_x1, &scissor_y1);
/* XXX: ONGOING BUG: Intel viewport scissor
*
* Intel gen6 drivers don't correctly handle offset viewports, since
* primitives aren't clipped within the bounds of the viewport. To
* workaround this we push our own clip for the viewport that will
* use scissoring to ensure we clip as expected.
*
* TODO: file a bug upstream!
*/
if (ctx->needs_viewport_scissor_workaround)
{
_cogl_util_scissor_intersect (framebuffer->viewport_x,
framebuffer->viewport_y,
framebuffer->viewport_x +
framebuffer->viewport_width,
framebuffer->viewport_y +
framebuffer->viewport_height,
&scissor_x0, &scissor_y0,
&scissor_x1, &scissor_y1);
framebuffer->viewport_age_for_scissor_workaround =
framebuffer->viewport_age;
ctx->viewport_scissor_workaround_framebuffer =
framebuffer;
}
/* Enable scissoring as soon as possible */
if (scissor_x0 >= scissor_x1 || scissor_y0 >= scissor_y1)
scissor_x0 = scissor_y0 = scissor_x1 = scissor_y1 = scissor_y_start = 0;
else
{
/* We store the entry coordinates in Cogl coordinate space
* but OpenGL requires the window origin to be the bottom
* left so we may need to convert the incoming coordinates.
*
* NB: Cogl forces all offscreen rendering to be done upside
* down so in this case no conversion is needed.
*/
if (cogl_is_offscreen (framebuffer))
scissor_y_start = scissor_y0;
else
{
int framebuffer_height =
cogl_framebuffer_get_height (framebuffer);
scissor_y_start = framebuffer_height - scissor_y1;
}
}
COGL_NOTE (CLIPPING, "Flushing scissor to (%i, %i, %i, %i)",
scissor_x0, scissor_y0,
scissor_x1, scissor_y1);
GE (ctx, glEnable (GL_SCISSOR_TEST));
GE (ctx, glScissor (scissor_x0, scissor_y_start,
scissor_x1 - scissor_x0,
scissor_y1 - scissor_y0));
/* Add all of the entries. This will end up adding them in the
reverse order that they were specified but as all of the clips
are intersecting it should work out the same regardless of the
order */
for (entry = stack; entry; entry = entry->parent)
{
switch (entry->type)
{
case COGL_CLIP_STACK_PATH:
{
CoglClipStackPath *path_entry = (CoglClipStackPath *) entry;
COGL_NOTE (CLIPPING, "Adding stencil clip for path");
add_stencil_clip_path (framebuffer,
path_entry->matrix_entry,
path_entry->path,
using_stencil_buffer,
TRUE);
using_stencil_buffer = TRUE;
break;
}
case COGL_CLIP_STACK_PRIMITIVE:
{
CoglClipStackPrimitive *primitive_entry =
(CoglClipStackPrimitive *) entry;
COGL_NOTE (CLIPPING, "Adding stencil clip for primitive");
add_stencil_clip_primitive (framebuffer,
primitive_entry->matrix_entry,
primitive_entry->primitive,
primitive_entry->bounds_x1,
primitive_entry->bounds_y1,
primitive_entry->bounds_x2,
primitive_entry->bounds_y2,
using_stencil_buffer,
TRUE);
using_stencil_buffer = TRUE;
break;
}
case COGL_CLIP_STACK_RECT:
{
CoglClipStackRect *rect = (CoglClipStackRect *) entry;
/* We don't need to do anything extra if the clip for this
rectangle was entirely described by its scissor bounds */
if (!rect->can_be_scissor)
{
/* If we support clip planes and we haven't already used
them then use that instead */
if (has_clip_planes)
{
COGL_NOTE (CLIPPING,
"Adding clip planes clip for rectangle");
set_clip_planes (framebuffer,
rect->matrix_entry,
rect->x0,
rect->y0,
rect->x1,
rect->y1);
using_clip_planes = TRUE;
/* We can't use clip planes a second time */
has_clip_planes = FALSE;
}
else
{
COGL_NOTE (CLIPPING, "Adding stencil clip for rectangle");
add_stencil_clip_rectangle (framebuffer,
rect->matrix_entry,
rect->x0,
rect->y0,
rect->x1,
rect->y1,
!using_stencil_buffer);
using_stencil_buffer = TRUE;
}
}
break;
}
case COGL_CLIP_STACK_WINDOW_RECT:
break;
/* We don't need to do anything for window space rectangles because
* their functionality is entirely implemented by the entry bounding
* box */
}
}
/* Enabling clip planes is delayed to now so that they won't affect
setting up the stencil buffer */
if (using_clip_planes)
enable_clip_planes (ctx);
ctx->current_clip_stack_uses_stencil = using_stencil_buffer;
}
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