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[sdf -> bsdf] Added the second pass of the '8SED'. 

Added the second pass of the 8SED algorithm. The second pass
transverse the bitmap from bottom to top and for each row
it sweeps forward and backward assigning distances to the
grid points.

* src/sdf/ftbsdf.c (second_pas): Added function to do the
  second pass of the 8SED algorithm on the bitmap.
This commit is contained in:
Anuj Verma 2020-07-27 08:52:24 +05:30 committed by anujverma
parent 6214e58893
commit 8564d5caf2
2 changed files with 164 additions and 2 deletions
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12
[GSoC]ChangeLog
View File

@ -1,3 +1,15 @@
2020-07-27 Anuj Verma <anujv@iitbhilai.ac.in>
[sdf -> bsdf] Added the second pass of the '8SED'.
Added the second pass of the 8SED algorithm. The second pass
transverse the bitmap from bottom to top and for each row
it sweeps forward and backward assigning distances to the
grid points.
* src/sdf/ftbsdf.c (second_pas): Added function to do the
second pass of the 8SED algorithm on the bitmap.
2020-07-26 Anuj Verma <anujv@iitbhilai.ac.in>
[sdf -> bsdf] Optimize the first pass of the 8SED.

154
src/sdf/ftbsdf.c
View File

@ -209,6 +209,7 @@
t[t_index].near.x = FT_INT_MAX;
t[t_index].near.y = FT_INT_MAX;
t[t_index].dist = 128 * ONE;
t[t_index].sign = -1;
continue;
}
@ -233,12 +234,16 @@
#else
if ( pixel_value )
{
t[t_index].dist = 0;
t[t_index].sign = 1;
}
else
{
t[t_index].near.x = FT_INT_MAX;
t[t_index].near.y = FT_INT_MAX;
t[t_index].dist = 128 * ONE;
t[t_index].sign = -1;
}
#endif
@ -402,6 +407,151 @@
}
}
/**************************************************************************
*
* @Function:
* second_pass
*
* @Description:
* [TODO]
*
* @Input:
* [TODO]
*
* @Return:
* [TODO]
*/
static void
second_pass( BSDF_Worker* worker )
{
FT_Int i, j; /* iterators */
FT_Int w, r; /* width, rows */
ED* dm; /* distance map */
dm = worker->distance_map;
w = worker->width;
r = worker->rows;
/* Start scanning from bottom to top and sweep each */
/* row back and forth comparing the distances of the */
/* neighborhood. Leave the last row as it has no down */
/* neighbor, it is already covered in the 1stscan of */
/* the image, that is from top to bottom. */
for ( j = r - 2; j >= 0; j-- )
{
FT_Int index;
FT_16D16 dist;
FT_16D16_Vec dist_vec;
ED* to_check;
ED* current;
/* Forward pass of rows (left -> right), leave, the */
/* first column, will be covered in backward pass. */
for ( i = 1; i < w; i++ )
{
index = j * w + i;
current = dm + index;
/* While checking for nearest point we first */
/* approximate the dist of the `current' point */
/* by adding the deviation ( which will be root */
/* 2 max ). And if the new value is lesser than */
/* the current value then only we calculate the */
/* actual distances using `FT_Vector_Length'. */
/* Of course this will be eliminated while using */
/* squared distances. */
/* left-up */
to_check = current + w - 1;
dist = to_check->dist + 2 * ONE; /* will be root(2) but 2 is fine */
if ( dist < current->dist )
{
dist_vec = to_check->near;
dist_vec.x -= ONE;
dist_vec.y += ONE;
dist = FT_Vector_Length( &dist_vec );
if ( dist < current->dist )
{
current->dist = dist;
current->near = dist_vec;
}
}
/* up */
to_check = current + w;
dist = to_check->dist + 1 * ONE; /* can only be 1 */
if ( dist < current->dist )
{
dist_vec = to_check->near;
dist_vec.y += ONE;
dist = FT_Vector_Length( &dist_vec );
if ( dist < current->dist )
{
current->dist = dist;
current->near = dist_vec;
}
}
/* up-right */
to_check = current + w + 1;
dist = to_check->dist + 2 * ONE;
if ( dist < current->dist )
{
dist_vec = to_check->near;
dist_vec.x += ONE;
dist_vec.y += ONE;
dist = FT_Vector_Length( &dist_vec );
if ( dist < current->dist )
{
current->dist = dist;
current->near = dist_vec;
}
}
/* left */
to_check = current - 1;
dist = to_check->dist + 1 * ONE;
if ( dist < current->dist )
{
dist_vec = to_check->near;
dist_vec.x -= ONE;
dist = FT_Vector_Length( &dist_vec );
if ( dist < current->dist )
{
current->dist = dist;
current->near = dist_vec;
}
}
}
/* Backward pass of rows (right -> left), leave, the */
/* last column, already covered in the forward pass. */
for ( i = w - 2; i >= 0; i-- )
{
index = j * w + i;
current = dm + index;
/* right */
to_check = current + 1;
dist = to_check->dist + 1 * ONE;
if ( dist < current->dist )
{
dist_vec = to_check->near;
dist_vec.x += ONE;
dist = FT_Vector_Length( &dist_vec );
if ( dist < current->dist )
{
current->dist = dist;
current->near = dist_vec;
}
}
}
}
}
/**************************************************************************
*
* @Function:
@ -432,7 +582,7 @@
first_pass( worker );
/* second scan of the image */
/* [TODO] */
second_pass( worker );
Exit:
return error;
@ -498,7 +648,7 @@
if ( final_dist > worker->params.spread * 1024 )
final_dist = worker->params.spread * 1024;
t_buffer[index] = final_dist;
t_buffer[index] = final_dist * worker->distance_map[index].sign;
}
}