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mutter/cogl/cogl-path.c
Neil Roberts 8afea98437 cogl-path: Don't try to union sub paths 
When drawing a path with only a single sub path, Cogl uses the
'even-odd' fill rule which means that if a part of the path intersects
with another part then the intersection would be inverted. However
when combining sub paths it treats them as separate paths and then
unions them together. This doesn't match the semantics of the even-odd
rule in SVG and Cairo. This patch makes it so that a new sub path is
just drawn as another triangle fan so that it will continue to invert
the stencil buffer. This is also much simpler and more efficient as
well as being more correct.

http://bugzilla.openedhand.com/show_bug.cgi?id=2088
2010-04-21 11:39:28 +01:00

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/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2007,2008,2009,2010 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/>.
*
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "cogl.h"
#include "cogl-internal.h"
#include "cogl-context.h"
#include "cogl-journal-private.h"
#include "cogl-material-private.h"
#include "cogl-framebuffer-private.h"
#include "cogl-path-private.h"
#include <string.h>
#include <math.h>
#define _COGL_MAX_BEZ_RECURSE_DEPTH 16
#ifdef HAVE_COGL_GL
#define glClientActiveTexture ctx->drv.pf_glClientActiveTexture
#endif
static void _cogl_path_free (CoglPath *path);
COGL_HANDLE_DEFINE (Path, path);
static void
_cogl_path_modify (CoglPath *path)
{
/* This needs to be called whenever the path is about to be modified
to implement copy-on-write semantics. Note that the current
mechanism assumes that a path will only ever be appended to (ie,
the path won't be cleared or have nodes in the middle
changed). This means that we don't need to keep track of how many
copies a node has because the copies can just keep track of the
number of nodes they should draw */
/* If this path is a copy then we need to actually copy the data so
we can modify it */
if (path->parent_path)
{
CoglPath *old_path = COGL_PATH (path->parent_path);
CoglPathNode *old_nodes = &g_array_index (old_path->path_nodes,
CoglPathNode, 0);
CoglPathNode *new_nodes;
int i;
path->path_nodes = g_array_new (FALSE, FALSE, sizeof (CoglPathNode));
/* The parent path may have extra nodes added after the copy was
made so we need to truncate it */
g_array_set_size (path->path_nodes, path->path_size);
memcpy (path->path_nodes->data, old_nodes,
sizeof (CoglPathNode) * path->path_size);
/* We need to make sure the last path size doesn't extend past
the total path size */
new_nodes = &g_array_index (path->path_nodes, CoglPathNode, 0);
for (i = 0; i < path->path_size; i += new_nodes[i].path_size)
if (new_nodes[i].path_size >= path->path_size)
new_nodes[i].path_size = path->path_size - i;
cogl_handle_unref (path->parent_path);
path->parent_path = COGL_INVALID_HANDLE;
}
}
static void
_cogl_path_add_node (gboolean new_sub_path,
float x,
float y)
{
CoglPathNode new_node;
CoglPath *path;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (ctx->current_path);
_cogl_path_modify (path);
new_node.x = x;
new_node.y = y;
new_node.path_size = 0;
if (new_sub_path || path->path_size == 0)
path->last_path = path->path_size;
g_array_append_val (path->path_nodes, new_node);
path->path_size++;
g_array_index (path->path_nodes, CoglPathNode, path->last_path).path_size++;
if (path->path_size == 1)
{
path->path_nodes_min.x = path->path_nodes_max.x = x;
path->path_nodes_min.y = path->path_nodes_max.y = y;
}
else
{
if (x < path->path_nodes_min.x) path->path_nodes_min.x = x;
if (x > path->path_nodes_max.x) path->path_nodes_max.x = x;
if (y < path->path_nodes_min.y) path->path_nodes_min.y = y;
if (y > path->path_nodes_max.y) path->path_nodes_max.y = y;
}
}
static void
_cogl_path_stroke_nodes (void)
{
unsigned int path_start = 0;
unsigned long enable_flags = COGL_ENABLE_VERTEX_ARRAY;
CoglPath *path;
CoglMaterialFlushOptions options;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (ctx->current_path);
_cogl_journal_flush ();
/* NB: _cogl_framebuffer_flush_state may disrupt various state (such
* as the material state) when flushing the clip stack, so should
* always be done first when preparing to draw. */
_cogl_framebuffer_flush_state (_cogl_get_framebuffer (), 0);
enable_flags |= _cogl_material_get_cogl_enable_flags (ctx->source_material);
_cogl_enable (enable_flags);
options.flags = COGL_MATERIAL_FLUSH_DISABLE_MASK;
/* disable all texture layers */
options.disable_layers = (guint32)~0;
_cogl_material_flush_gl_state (ctx->source_material, &options);
while (path_start < path->path_size)
{
CoglPathNode *node = &g_array_index (path->path_nodes, CoglPathNode,
path_start);
GE( glVertexPointer (2, GL_FLOAT, sizeof (CoglPathNode), &node->x) );
/* We need to limit the size of the sub path to the size of our
path in case this path is a copy and the parent path has
grown */
GE( glDrawArrays (GL_LINE_STRIP, 0,
MIN (node->path_size, path->path_size - path_start)) );
path_start += node->path_size;
}
}
static void
_cogl_path_get_bounds (floatVec2 nodes_min,
floatVec2 nodes_max,
float *bounds_x,
float *bounds_y,
float *bounds_w,
float *bounds_h)
{
*bounds_x = nodes_min.x;
*bounds_y = nodes_min.y;
*bounds_w = nodes_max.x - *bounds_x;
*bounds_h = nodes_max.y - *bounds_y;
}
void
_cogl_add_path_to_stencil_buffer (CoglHandle path_handle,
gboolean merge,
gboolean need_clear)
{
unsigned int path_start = 0;
float bounds_x;
float bounds_y;
float bounds_w;
float bounds_h;
unsigned long enable_flags = COGL_ENABLE_VERTEX_ARRAY;
CoglHandle prev_source;
int i;
CoglHandle framebuffer = _cogl_get_framebuffer ();
CoglMatrixStack *modelview_stack =
_cogl_framebuffer_get_modelview_stack (framebuffer);
CoglMatrixStack *projection_stack =
_cogl_framebuffer_get_projection_stack (framebuffer);
CoglPath *path;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (path_handle);
/* We don't track changes to the stencil buffer in the journal
* so we need to flush any batched geometry first */
_cogl_journal_flush ();
/* NB: _cogl_framebuffer_flush_state may disrupt various state (such
* as the material state) when flushing the clip stack, so should
* always be done first when preparing to draw. */
_cogl_framebuffer_flush_state (framebuffer, 0);
/* Just setup a simple material that doesn't use texturing... */
prev_source = cogl_handle_ref (ctx->source_material);
cogl_set_source (ctx->stencil_material);
_cogl_material_flush_gl_state (ctx->source_material, NULL);
enable_flags |=
_cogl_material_get_cogl_enable_flags (ctx->source_material);
_cogl_enable (enable_flags);
_cogl_path_get_bounds (path->path_nodes_min, path->path_nodes_max,
&bounds_x, &bounds_y, &bounds_w, &bounds_h);
GE( glEnable (GL_STENCIL_TEST) );
GE( glColorMask (FALSE, FALSE, FALSE, FALSE) );
GE( glDepthMask (FALSE) );
if (merge)
{
GE (glStencilMask (2));
GE (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)
cogl_clear (NULL, COGL_BUFFER_BIT_STENCIL);
else
{
/* Just clear the bounding box */
GE( glStencilMask (~(GLuint) 0) );
GE( glStencilOp (GL_ZERO, GL_ZERO, GL_ZERO) );
cogl_rectangle (bounds_x, bounds_y,
bounds_x + bounds_w, bounds_y + bounds_h);
/* Make sure the rectangle hits the stencil buffer before
* directly changing other GL state. */
_cogl_journal_flush ();
/* NB: The journal flushing may trash the modelview state and
* enable flags */
_cogl_matrix_stack_flush_to_gl (modelview_stack,
COGL_MATRIX_MODELVIEW);
_cogl_enable (enable_flags);
}
GE (glStencilMask (1));
GE (glStencilFunc (GL_LEQUAL, 0x1, 0x3));
}
GE (glStencilOp (GL_INVERT, GL_INVERT, GL_INVERT));
for (i = 0; i < ctx->n_texcoord_arrays_enabled; i++)
{
GE (glClientActiveTexture (GL_TEXTURE0 + i));
GE (glDisableClientState (GL_TEXTURE_COORD_ARRAY));
}
ctx->n_texcoord_arrays_enabled = 0;
while (path_start < path->path_size)
{
CoglPathNode *node =
&g_array_index (path->path_nodes, CoglPathNode, path_start);
GE (glVertexPointer (2, GL_FLOAT, sizeof (CoglPathNode), &node->x));
/* We need to limit the size of the sub path to the size of our
path in case this path is a copy and the parent path has
grown */
GE (glDrawArrays (GL_TRIANGLE_FAN, 0,
MIN (node->path_size, path->path_size - path_start)));
path_start += node->path_size;
}
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 (glStencilMask (3));
GE (glStencilFunc (GL_NEVER, 0x2, 0x3));
GE (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_matrix_stack_push (projection_stack);
_cogl_matrix_stack_load_identity (projection_stack);
_cogl_matrix_stack_flush_to_gl (projection_stack,
COGL_MATRIX_PROJECTION);
_cogl_matrix_stack_push (modelview_stack);
_cogl_matrix_stack_load_identity (modelview_stack);
_cogl_matrix_stack_flush_to_gl (modelview_stack,
COGL_MATRIX_MODELVIEW);
cogl_rectangle (-1.0, -1.0, 1.0, 1.0);
cogl_rectangle (-1.0, -1.0, 1.0, 1.0);
/* Make sure these rectangles hit the stencil buffer before we
* restore the stencil op/func. */
_cogl_journal_flush ();
_cogl_matrix_stack_pop (modelview_stack);
_cogl_matrix_stack_pop (projection_stack);
}
GE (glStencilMask (~(GLuint) 0));
GE (glDepthMask (TRUE));
GE (glColorMask (TRUE, TRUE, TRUE, TRUE));
GE (glStencilFunc (GL_EQUAL, 0x1, 0x1));
GE (glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP));
/* restore the original material */
cogl_set_source (prev_source);
cogl_handle_unref (prev_source);
}
static int
compare_ints (gconstpointer a,
gconstpointer b)
{
return GPOINTER_TO_INT(a)-GPOINTER_TO_INT(b);
}
static void
_cogl_path_fill_nodes_scanlines (CoglPathNode *path,
unsigned int path_size,
int bounds_x,
int bounds_y,
unsigned int bounds_w,
unsigned int bounds_h)
{
/* This is our edge list it stores intersections between our
* curve and scanlines, it should probably be implemented with a
* data structure that has smaller overhead for inserting the
* curve/scanline intersections.
*/
GSList **scanlines = g_alloca (bounds_h * sizeof (GSList *));
int i;
int prev_x;
int prev_y;
int first_x;
int first_y;
int lastdir = -2; /* last direction we vere moving */
int lastline = -1; /* the previous scanline we added to */
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
/* We are going to use GL to draw directly so make sure any
* previously batched geometry gets to GL before we start...
*/
_cogl_journal_flush ();
/* NB: _cogl_framebuffer_flush_state may disrupt various state (such
* as the material state) when flushing the clip stack, so should
* always be done first when preparing to draw. */
_cogl_framebuffer_flush_state (_cogl_get_framebuffer (), 0);
_cogl_material_flush_gl_state (ctx->source_material, NULL);
_cogl_enable (COGL_ENABLE_VERTEX_ARRAY
| (ctx->color_alpha < 255 ? COGL_ENABLE_BLEND : 0));
/* clear scanline intersection lists */
for (i = 0; i < bounds_h; i++)
scanlines[i]=NULL;
first_x = prev_x = path->x;
first_y = prev_y = path->y;
/* create scanline intersection list */
for (i=1; i < path_size; i++)
{
int dest_x = path[i].x;
int dest_y = path[i].y;
int ydir;
int dx;
int dy;
int y;
fill_close:
dx = dest_x - prev_x;
dy = dest_y - prev_y;
if (dy < 0)
ydir = -1;
else if (dy > 0)
ydir = 1;
else
ydir = 0;
/* do linear interpolation between vertices */
for (y = prev_y; y != dest_y; y += ydir)
{
/* only add a point if the scanline has changed and we're
* within bounds.
*/
if (y - bounds_y >= 0 &&
y - bounds_y < bounds_h &&
lastline != y)
{
int x = prev_x + (dx * (y-prev_y)) / dy;
scanlines[ y - bounds_y ]=
g_slist_insert_sorted (scanlines[ y - bounds_y],
GINT_TO_POINTER(x),
compare_ints);
if (ydir != lastdir && /* add a double entry when changing */
lastdir != -2) /* vertical direction */
scanlines[ y - bounds_y ]=
g_slist_insert_sorted (scanlines[ y - bounds_y],
GINT_TO_POINTER(x),
compare_ints);
lastdir = ydir;
lastline = y;
}
}
prev_x = dest_x;
prev_y = dest_y;
/* if we're on the last knot, fake the first vertex being a
next one */
if (path_size == i+1)
{
dest_x = first_x;
dest_y = first_y;
i++; /* to make the loop finally end */
goto fill_close;
}
}
{
int spans = 0;
int span_no;
GLfloat *coords;
/* count number of spans */
for (i = 0; i < bounds_h; i++)
{
GSList *iter = scanlines[i];
while (iter)
{
GSList *next = iter->next;
if (!next)
{
break;
}
/* draw the segments that should be visible */
spans ++;
iter = next->next;
}
}
coords = g_malloc0 (spans * sizeof (GLfloat) * 3 * 2 * 2);
span_no = 0;
/* build list of triangles */
for (i = 0; i < bounds_h; i++)
{
GSList *iter = scanlines[i];
while (iter)
{
GSList *next = iter->next;
GLfloat x_0, x_1;
GLfloat y_0, y_1;
if (!next)
break;
x_0 = GPOINTER_TO_INT (iter->data);
x_1 = GPOINTER_TO_INT (next->data);
y_0 = bounds_y + i;
y_1 = bounds_y + i + 1.0625f;
/* render scanlines 1.0625 high to avoid gaps when
transformed */
coords[span_no * 12 + 0] = x_0;
coords[span_no * 12 + 1] = y_0;
coords[span_no * 12 + 2] = x_1;
coords[span_no * 12 + 3] = y_0;
coords[span_no * 12 + 4] = x_1;
coords[span_no * 12 + 5] = y_1;
coords[span_no * 12 + 6] = x_0;
coords[span_no * 12 + 7] = y_0;
coords[span_no * 12 + 8] = x_0;
coords[span_no * 12 + 9] = y_1;
coords[span_no * 12 + 10] = x_1;
coords[span_no * 12 + 11] = y_1;
span_no ++;
iter = next->next;
}
}
for (i = 0; i < bounds_h; i++)
g_slist_free (scanlines[i]);
/* render triangles */
GE (glVertexPointer (2, GL_FLOAT, 0, coords ));
GE (glDrawArrays (GL_TRIANGLES, 0, spans * 2 * 3));
g_free (coords);
}
}
static void
_cogl_path_fill_nodes (void)
{
CoglPath *path;
float bounds_x;
float bounds_y;
float bounds_w;
float bounds_h;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (ctx->current_path);
_cogl_path_get_bounds (path->path_nodes_min, path->path_nodes_max,
&bounds_x, &bounds_y, &bounds_w, &bounds_h);
if (G_LIKELY (!(cogl_debug_flags & COGL_DEBUG_FORCE_SCANLINE_PATHS)) &&
cogl_features_available (COGL_FEATURE_STENCIL_BUFFER))
{
CoglHandle framebuffer;
CoglClipState *clip_state;
_cogl_journal_flush ();
framebuffer = _cogl_get_framebuffer ();
clip_state = _cogl_framebuffer_get_clip_state (framebuffer);
_cogl_add_path_to_stencil_buffer (ctx->current_path,
clip_state->stencil_used,
FALSE);
cogl_rectangle (bounds_x, bounds_y,
bounds_x + bounds_w, bounds_y + bounds_h);
/* The stencil buffer now contains garbage so the clip area needs to
* be rebuilt.
*
* NB: We only ever try and update the clip state during
* _cogl_journal_init (when we flush the framebuffer state) which is
* only called when the journal first gets something logged in it; so
* we call cogl_flush() to emtpy the journal.
*/
cogl_flush ();
_cogl_clip_state_dirty (clip_state);
}
else
{
unsigned int path_start = 0;
while (path_start < path->path_size)
{
CoglPathNode *node = &g_array_index (path->path_nodes, CoglPathNode,
path_start);
/* We need to limit the size of the sub path to the size of
our path in case this path is a copy and the parent path
has grown */
_cogl_path_fill_nodes_scanlines (node,
MIN (node->path_size,
path->path_size - path_start),
bounds_x, bounds_y,
bounds_w, bounds_h);
path_start += node->path_size;
}
}
}
void
cogl_path_fill (void)
{
cogl_path_fill_preserve ();
cogl_path_new ();
}
void
cogl_path_fill_preserve (void)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
if (COGL_PATH (ctx->current_path)->path_size == 0)
return;
_cogl_path_fill_nodes ();
}
void
cogl_path_stroke (void)
{
cogl_path_stroke_preserve ();
cogl_path_new ();
}
void
cogl_path_stroke_preserve (void)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
if (COGL_PATH (ctx->current_path)->path_size == 0)
return;
_cogl_path_stroke_nodes ();
}
void
cogl_path_move_to (float x,
float y)
{
CoglPath *path;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
_cogl_path_add_node (TRUE, x, y);
path = COGL_PATH (ctx->current_path);
path->path_start.x = x;
path->path_start.y = y;
path->path_pen = path->path_start;
}
void
cogl_path_rel_move_to (float x,
float y)
{
CoglPath *path;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (ctx->current_path);
cogl_path_move_to (path->path_pen.x + x,
path->path_pen.y + y);
}
void
cogl_path_line_to (float x,
float y)
{
CoglPath *path;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
_cogl_path_add_node (FALSE, x, y);
path = COGL_PATH (ctx->current_path);
path->path_pen.x = x;
path->path_pen.y = y;
}
void
cogl_path_rel_line_to (float x,
float y)
{
CoglPath *path;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (ctx->current_path);
cogl_path_line_to (path->path_pen.x + x,
path->path_pen.y + y);
}
void
cogl_path_close (void)
{
CoglPath *path;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (ctx->current_path);
_cogl_path_add_node (FALSE, path->path_start.x,
path->path_start.y);
path->path_pen = path->path_start;
}
void
cogl_path_new (void)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
cogl_handle_unref (ctx->current_path);
ctx->current_path = _cogl_path_new ();
}
void
cogl_path_line (float x_1,
float y_1,
float x_2,
float y_2)
{
cogl_path_move_to (x_1, y_1);
cogl_path_line_to (x_2, y_2);
}
void
cogl_path_polyline (float *coords,
int num_points)
{
int c = 0;
cogl_path_move_to (coords[0], coords[1]);
for (c = 1; c < num_points; ++c)
cogl_path_line_to (coords[2*c], coords[2*c+1]);
}
void
cogl_path_polygon (float *coords,
int num_points)
{
cogl_path_polyline (coords, num_points);
cogl_path_close ();
}
void
cogl_path_rectangle (float x_1,
float y_1,
float x_2,
float y_2)
{
cogl_path_move_to (x_1, y_1);
cogl_path_line_to (x_2, y_1);
cogl_path_line_to (x_2, y_2);
cogl_path_line_to (x_1, y_2);
cogl_path_close ();
}
static void
_cogl_path_arc (float center_x,
float center_y,
float radius_x,
float radius_y,
float angle_1,
float angle_2,
float angle_step,
unsigned int move_first)
{
float a = 0x0;
float cosa = 0x0;
float sina = 0x0;
float px = 0x0;
float py = 0x0;
/* Fix invalid angles */
if (angle_1 == angle_2 || angle_step == 0x0)
return;
if (angle_step < 0x0)
angle_step = -angle_step;
/* Walk the arc by given step */
a = angle_1;
while (a != angle_2)
{
cosa = cosf (a * (G_PI/180.0));
sina = sinf (a * (G_PI/180.0));
px = center_x + (cosa * radius_x);
py = center_y + (sina * radius_y);
if (a == angle_1 && move_first)
cogl_path_move_to (px, py);
else
cogl_path_line_to (px, py);
if (G_LIKELY (angle_2 > angle_1))
{
a += angle_step;
if (a > angle_2)
a = angle_2;
}
else
{
a -= angle_step;
if (a < angle_2)
a = angle_2;
}
}
/* Make sure the final point is drawn */
cosa = cosf (angle_2 * (G_PI/180.0));
sina = sinf (angle_2 * (G_PI/180.0));
px = center_x + (cosa * radius_x);
py = center_y + (sina * radius_y);
cogl_path_line_to (px, py);
}
void
cogl_path_arc (float center_x,
float center_y,
float radius_x,
float radius_y,
float angle_1,
float angle_2)
{
float angle_step = 10;
/* it is documented that a move to is needed to create a freestanding
* arc
*/
_cogl_path_arc (center_x, center_y,
radius_x, radius_y,
angle_1, angle_2,
angle_step, 0 /* no move */);
}
void
cogl_path_arc_rel (float center_x,
float center_y,
float radius_x,
float radius_y,
float angle_1,
float angle_2,
float angle_step)
{
CoglPath *path;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (ctx->current_path);
_cogl_path_arc (path->path_pen.x + center_x,
path->path_pen.y + center_y,
radius_x, radius_y,
angle_1, angle_2,
angle_step, 0 /* no move */);
}
void
cogl_path_ellipse (float center_x,
float center_y,
float radius_x,
float radius_y)
{
float angle_step = 10;
/* FIXME: if shows to be slow might be optimized
* by mirroring just a quarter of it */
_cogl_path_arc (center_x, center_y,
radius_x, radius_y,
0, 360,
angle_step, 1 /* move first */);
cogl_path_close();
}
void
cogl_path_round_rectangle (float x_1,
float y_1,
float x_2,
float y_2,
float radius,
float arc_step)
{
CoglPath *path;
float inner_width = x_2 - x_1 - radius * 2;
float inner_height = y_2 - y_1 - radius * 2;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (ctx->current_path);
cogl_path_move_to (x_1, y_1 + radius);
cogl_path_arc_rel (radius, 0,
radius, radius,
180,
270,
arc_step);
cogl_path_line_to (path->path_pen.x + inner_width,
path->path_pen.y);
cogl_path_arc_rel (0, radius,
radius, radius,
-90,
0,
arc_step);
cogl_path_line_to (path->path_pen.x,
path->path_pen.y + inner_height);
cogl_path_arc_rel (-radius, 0,
radius, radius,
0,
90,
arc_step);
cogl_path_line_to (path->path_pen.x - inner_width,
path->path_pen.y);
cogl_path_arc_rel (0, -radius,
radius, radius,
90,
180,
arc_step);
cogl_path_close ();
}
static void
_cogl_path_bezier3_sub (CoglBezCubic *cubic)
{
CoglBezCubic cubics[_COGL_MAX_BEZ_RECURSE_DEPTH];
CoglBezCubic *cleft;
CoglBezCubic *cright;
CoglBezCubic *c;
floatVec2 dif1;
floatVec2 dif2;
floatVec2 mm;
floatVec2 c1;
floatVec2 c2;
floatVec2 c3;
floatVec2 c4;
floatVec2 c5;
int cindex;
/* Put first curve on stack */
cubics[0] = *cubic;
cindex = 0;
while (cindex >= 0)
{
c = &cubics[cindex];
/* Calculate distance of control points from their
* counterparts on the line between end points */
dif1.x = (c->p2.x * 3) - (c->p1.x * 2) - c->p4.x;
dif1.y = (c->p2.y * 3) - (c->p1.y * 2) - c->p4.y;
dif2.x = (c->p3.x * 3) - (c->p4.x * 2) - c->p1.x;
dif2.y = (c->p3.y * 3) - (c->p4.y * 2) - c->p1.y;
if (dif1.x < 0)
dif1.x = -dif1.x;
if (dif1.y < 0)
dif1.y = -dif1.y;
if (dif2.x < 0)
dif2.x = -dif2.x;
if (dif2.y < 0)
dif2.y = -dif2.y;
/* Pick the greatest of two distances */
if (dif1.x < dif2.x) dif1.x = dif2.x;
if (dif1.y < dif2.y) dif1.y = dif2.y;
/* Cancel if the curve is flat enough */
if (dif1.x + dif1.y <= 1.0 ||
cindex == _COGL_MAX_BEZ_RECURSE_DEPTH-1)
{
/* Add subdivision point (skip last) */
if (cindex == 0)
return;
_cogl_path_add_node (FALSE, c->p4.x, c->p4.y);
--cindex;
continue;
}
/* Left recursion goes on top of stack! */
cright = c; cleft = &cubics[++cindex];
/* Subdivide into 2 sub-curves */
c1.x = ((c->p1.x + c->p2.x) / 2);
c1.y = ((c->p1.y + c->p2.y) / 2);
mm.x = ((c->p2.x + c->p3.x) / 2);
mm.y = ((c->p2.y + c->p3.y) / 2);
c5.x = ((c->p3.x + c->p4.x) / 2);
c5.y = ((c->p3.y + c->p4.y) / 2);
c2.x = ((c1.x + mm.x) / 2);
c2.y = ((c1.y + mm.y) / 2);
c4.x = ((mm.x + c5.x) / 2);
c4.y = ((mm.y + c5.y) / 2);
c3.x = ((c2.x + c4.x) / 2);
c3.y = ((c2.y + c4.y) / 2);
/* Add left recursion to stack */
cleft->p1 = c->p1;
cleft->p2 = c1;
cleft->p3 = c2;
cleft->p4 = c3;
/* Add right recursion to stack */
cright->p1 = c3;
cright->p2 = c4;
cright->p3 = c5;
cright->p4 = c->p4;
}
}
void
cogl_path_curve_to (float x_1,
float y_1,
float x_2,
float y_2,
float x_3,
float y_3)
{
CoglBezCubic cubic;
CoglPath *path;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (ctx->current_path);
/* Prepare cubic curve */
cubic.p1 = path->path_pen;
cubic.p2.x = x_1;
cubic.p2.y = y_1;
cubic.p3.x = x_2;
cubic.p3.y = y_2;
cubic.p4.x = x_3;
cubic.p4.y = y_3;
/* Run subdivision */
_cogl_path_bezier3_sub (&cubic);
/* Add last point */
_cogl_path_add_node (FALSE, cubic.p4.x, cubic.p4.y);
path->path_pen = cubic.p4;
}
void
cogl_path_rel_curve_to (float x_1,
float y_1,
float x_2,
float y_2,
float x_3,
float y_3)
{
CoglPath *path;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (ctx->current_path);
cogl_path_curve_to (path->path_pen.x + x_1,
path->path_pen.y + y_1,
path->path_pen.x + x_2,
path->path_pen.y + y_2,
path->path_pen.x + x_3,
path->path_pen.y + y_3);
}
CoglHandle
cogl_path_get (void)
{
_COGL_GET_CONTEXT (ctx, FALSE);
return ctx->current_path;
}
void
cogl_path_set (CoglHandle handle)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
if (!cogl_is_path (handle))
return;
/* Reference the new handle first in case it is the same as the old
handle */
cogl_handle_ref (handle);
cogl_handle_unref (ctx->current_path);
ctx->current_path = handle;
}
CoglHandle
_cogl_path_new (void)
{
CoglPath *path;
path = g_slice_new (CoglPath);
path->path_nodes = g_array_new (FALSE, FALSE, sizeof (CoglPathNode));
path->last_path = 0;
path->parent_path = COGL_INVALID_HANDLE;
path->path_size = 0;
return _cogl_path_handle_new (path);
}
CoglHandle
cogl_path_copy (CoglHandle handle)
{
CoglPath *old_path, *new_path;
_COGL_GET_CONTEXT (ctx, FALSE);
if (!cogl_is_path (handle))
return COGL_INVALID_HANDLE;
old_path = COGL_PATH (handle);
new_path = g_slice_dup (CoglPath, old_path);
new_path->parent_path = cogl_handle_ref (handle);
return _cogl_path_handle_new (new_path);
}
static void
_cogl_path_free (CoglPath *path)
{
if (path->parent_path)
cogl_handle_unref (path->parent_path);
else
g_array_free (path->path_nodes, TRUE);
g_slice_free (CoglPath, path);
}
/* If second order beziers were needed the following code could
* be re-enabled:
*/
#if 0
static void
_cogl_path_bezier2_sub (CoglBezQuad *quad)
{
CoglBezQuad quads[_COGL_MAX_BEZ_RECURSE_DEPTH];
CoglBezQuad *qleft;
CoglBezQuad *qright;
CoglBezQuad *q;
floatVec2 mid;
floatVec2 dif;
floatVec2 c1;
floatVec2 c2;
floatVec2 c3;
int qindex;
/* Put first curve on stack */
quads[0] = *quad;
qindex = 0;
/* While stack is not empty */
while (qindex >= 0)
{
q = &quads[qindex];
/* Calculate distance of control point from its
* counterpart on the line between end points */
mid.x = ((q->p1.x + q->p3.x) / 2);
mid.y = ((q->p1.y + q->p3.y) / 2);
dif.x = (q->p2.x - mid.x);
dif.y = (q->p2.y - mid.y);
if (dif.x < 0) dif.x = -dif.x;
if (dif.y < 0) dif.y = -dif.y;
/* Cancel if the curve is flat enough */
if (dif.x + dif.y <= 1.0 ||
qindex == _COGL_MAX_BEZ_RECURSE_DEPTH - 1)
{
/* Add subdivision point (skip last) */
if (qindex == 0) return;
_cogl_path_add_node (FALSE, q->p3.x, q->p3.y);
--qindex; continue;
}
/* Left recursion goes on top of stack! */
qright = q; qleft = &quads[++qindex];
/* Subdivide into 2 sub-curves */
c1.x = ((q->p1.x + q->p2.x) / 2);
c1.y = ((q->p1.y + q->p2.y) / 2);
c3.x = ((q->p2.x + q->p3.x) / 2);
c3.y = ((q->p2.y + q->p3.y) / 2);
c2.x = ((c1.x + c3.x) / 2);
c2.y = ((c1.y + c3.y) / 2);
/* Add left recursion onto stack */
qleft->p1 = q->p1;
qleft->p2 = c1;
qleft->p3 = c2;
/* Add right recursion onto stack */
qright->p1 = c2;
qright->p2 = c3;
qright->p3 = q->p3;
}
}
void
cogl_path_curve2_to (float x_1,
float y_1,
float x_2,
float y_2)
{
CoglPath *path;
CoglBezQuad quad;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (ctx->current_path);
/* Prepare quadratic curve */
quad.p1 = ctx->path_pen;
quad.p2.x = x_1;
quad.p2.y = y_1;
quad.p3.x = x_2;
quad.p3.y = y_2;
/* Run subdivision */
_cogl_path_bezier2_sub (&quad);
/* Add last point */
_cogl_path_add_node (FALSE, quad.p3.x, quad.p3.y);
path->path_pen = quad.p3;
}
void
cogl_rel_curve2_to (float x_1,
float y_1,
float x_2,
float y_2)
{
CoglPath *path;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
path = COGL_PATH (ctx->current_path);
cogl_path_curve2_to (path->path_pen.x + x_1,
path->path_pen.y + y_1,
path->path_pen.x + x_2,
path->path_pen.y + y_2);
}
#endif
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