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7d9b733446
mutter/cogl/cogl-path.c
Robert Bragg 7d9b733446 cogl: cleanly separate primitives + paths code 
The function prototypes for the primitives API were spread between
cogl-path.h and cogl-texture.h and should have been in a
cogl-primitives.h.

As well as shuffling the prototypes around into more sensible places
this commit splits the cogl-path API out from cogl-primitives.c into
a cogl-path.c
2010-02-12 14:05:01 +00:00

1122 lines
29 KiB
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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, 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-context.h"
#include "cogl-journal-private.h"
#include "cogl-material-private.h"
#include "cogl-framebuffer-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_add_node (gboolean new_sub_path,
float x,
float y)
{
CoglPathNode new_node;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
new_node.x = x;
new_node.y = y;
new_node.path_size = 0;
if (new_sub_path || ctx->path_nodes->len == 0)
ctx->last_path = ctx->path_nodes->len;
g_array_append_val (ctx->path_nodes, new_node);
g_array_index (ctx->path_nodes, CoglPathNode, ctx->last_path).path_size++;
if (ctx->path_nodes->len == 1)
{
ctx->path_nodes_min.x = ctx->path_nodes_max.x = x;
ctx->path_nodes_min.y = ctx->path_nodes_max.y = y;
}
else
{
if (x < ctx->path_nodes_min.x) ctx->path_nodes_min.x = x;
if (x > ctx->path_nodes_max.x) ctx->path_nodes_max.x = x;
if (y < ctx->path_nodes_min.y) ctx->path_nodes_min.y = y;
if (y > ctx->path_nodes_max.y) ctx->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;
CoglMaterialFlushOptions options;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
_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 < ctx->path_nodes->len)
{
CoglPathNode *path = &g_array_index (ctx->path_nodes, CoglPathNode,
path_start);
GE( glVertexPointer (2, GL_FLOAT, sizeof (CoglPathNode),
(guint8 *) path
+ G_STRUCT_OFFSET (CoglPathNode, x)) );
GE( glDrawArrays (GL_LINE_STRIP, 0, path->path_size) );
path_start += path->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 (floatVec2 nodes_min,
floatVec2 nodes_max,
unsigned int path_size,
CoglPathNode *path,
gboolean merge,
gboolean need_clear)
{
unsigned int path_start = 0;
unsigned int sub_path_num = 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);
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
/* 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 (nodes_min, 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_size)
{
GE (glVertexPointer (2, GL_FLOAT, sizeof (CoglPathNode),
(guint8 *) path
+ G_STRUCT_OFFSET (CoglPathNode, x)));
GE (glDrawArrays (GL_TRIANGLE_FAN, 0, path->path_size));
if (sub_path_num > 0)
{
/* Union the two stencil buffers bits into the least
significant bit */
GE (glStencilMask (merge ? 6 : 3));
GE (glStencilOp (GL_ZERO, GL_REPLACE, GL_REPLACE));
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 (glStencilOp (GL_INVERT, GL_INVERT, GL_INVERT));
}
GE (glStencilMask (merge ? 4 : 2));
path_start += path->path_size;
path += path->path_size;
sub_path_num++;
}
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)
{
float bounds_x;
float bounds_y;
float bounds_w;
float bounds_h;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
_cogl_path_get_bounds (ctx->path_nodes_min, ctx->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;
CoglClipStackState *clip_state;
_cogl_journal_flush ();
framebuffer = _cogl_get_framebuffer ();
clip_state = _cogl_framebuffer_get_clip_state (framebuffer);
_cogl_add_path_to_stencil_buffer (ctx->path_nodes_min,
ctx->path_nodes_max,
ctx->path_nodes->len,
&g_array_index (ctx->path_nodes,
CoglPathNode, 0),
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_stack_state_dirty (clip_state);
}
else
{
unsigned int path_start = 0;
while (path_start < ctx->path_nodes->len)
{
CoglPathNode *path = &g_array_index (ctx->path_nodes, CoglPathNode,
path_start);
_cogl_path_fill_nodes_scanlines (path,
path->path_size,
bounds_x, bounds_y,
bounds_w, bounds_h);
path_start += path->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 (ctx->path_nodes->len == 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 (ctx->path_nodes->len == 0)
return;
_cogl_path_stroke_nodes ();
}
void
cogl_path_move_to (float x,
float y)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
/* FIXME: handle multiple contours maybe? */
_cogl_path_add_node (TRUE, x, y);
ctx->path_start.x = x;
ctx->path_start.y = y;
ctx->path_pen = ctx->path_start;
}
void
cogl_path_rel_move_to (float x,
float y)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
cogl_path_move_to (ctx->path_pen.x + x,
ctx->path_pen.y + y);
}
void
cogl_path_line_to (float x,
float y)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
_cogl_path_add_node (FALSE, x, y);
ctx->path_pen.x = x;
ctx->path_pen.y = y;
}
void
cogl_path_rel_line_to (float x,
float y)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
cogl_path_line_to (ctx->path_pen.x + x,
ctx->path_pen.y + y);
}
void
cogl_path_close (void)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
_cogl_path_add_node (FALSE, ctx->path_start.x, ctx->path_start.y);
ctx->path_pen = ctx->path_start;
}
void
cogl_path_new (void)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
g_array_set_size (ctx->path_nodes, 0);
}
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)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
_cogl_path_arc (ctx->path_pen.x + center_x,
ctx->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)
{
float inner_width = x_2 - x_1 - radius * 2;
float inner_height = y_2 - y_1 - radius * 2;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
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 (ctx->path_pen.x + inner_width,
ctx->path_pen.y);
cogl_path_arc_rel (0, radius,
radius, radius,
-90,
0,
arc_step);
cogl_path_line_to (ctx->path_pen.x,
ctx->path_pen.y + inner_height);
cogl_path_arc_rel (-radius, 0,
radius, radius,
0,
90,
arc_step);
cogl_path_line_to (ctx->path_pen.x - inner_width,
ctx->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;
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
/* Prepare cubic curve */
cubic.p1 = ctx->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);
ctx->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)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
cogl_path_curve_to (ctx->path_pen.x + x_1,
ctx->path_pen.y + y_1,
ctx->path_pen.x + x_2,
ctx->path_pen.y + y_2,
ctx->path_pen.x + x_3,
ctx->path_pen.y + y_3);
}
/* 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)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
CoglBezQuad quad;
/* 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);
ctx->path_pen = quad.p3;
}
void
cogl_rel_curve2_to (float x_1,
float y_1,
float x_2,
float y_2)
{
_COGL_GET_CONTEXT (ctx, NO_RETVAL);
cogl_path_curve2_to (ctx->path_pen.x + x_1,
ctx->path_pen.y + y_1,
ctx->path_pen.x + x_2,
ctx->path_pen.y + y_2);
}
#endif
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