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[sdf] Make squared distances toggleable.

This commit is contained in:
Anuj Verma 2020-07-01 16:51:37 +05:30 committed by anujverma
parent 97474a7072
commit d0e3074738
2 changed files with 82 additions and 26 deletions
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16
[GSoC]ChangeLog
View File

@ -1,3 +1,19 @@
2020-07-01 Anuj Verma <anujv@iitbhilai.ac.in>
[sdf] Make squared distances toggleable.
* src/sdf/ftsdf.c (SDF_Signed_Distance): Renamed
squared_distance to distance. It can now represent
both squared as well as actual distances.
* src/sdf/ftsdf.c (USE_SQUARED_DISTANCES): Added macro
which control weather to do computation is squared
distances or actual distances. This can be used to
avoid overflow when generating large SDF bitmaps.
* src/sdf/ftsdf.c: Make sure not to exceed line length
of 78.
2020-07-01 Anuj Verma <anujv@iitbhilai.ac.in>
* src/sdf/ftsdf.c (get_min_distance_conic): In case

92
src/sdf/ftsdf.c
View File

@ -7,15 +7,34 @@
#include "ftsdferrs.h"
/**************************************************************************
*
* definitions
*
*/
/* If it is defined to 1 then the rasterizer will use squared distances */
/* for computation. It can greatly improve the performance but there is */
/* a chance of overflow and artifacts. You can safely use is upto a */
/* pixel size of 128. */
#ifndef USE_SQUARED_DISTANCES
#define USE_SQUARED_DISTANCES 0
#endif
/**************************************************************************
*
* macros
*
*/
#define FT_INT_26D6( x ) ( x * 64 ) /* convert int to 26.6 fixed point */
#define FT_INT_16D16( x ) ( x * 65536 ) /* convert int to 16.16 fixed point */
#define FT_26D6_16D16( x ) ( x * 1024 ) /* convert 26.6 to 16.16 fixed point */
/* convert int to 26.6 fixed point */
#define FT_INT_26D6( x ) ( x * 64 )
/* convert int to 16.16 fixed point */
#define FT_INT_16D16( x ) ( x * 65536 )
/* convert 26.6 to 16.16 fixed point */
#define FT_26D6_16D16( x ) ( x * 1024 )
/* Convenient macro which calls the function */
@ -31,6 +50,19 @@
#define VEC_26D6_DOT( p, q ) ( MUL_26D6( p.x, q.x ) + \
MUL_26D6( p.y, q.y ) )
/* [IMPORTANT]: The macro `VECTOR_LENGTH_16D16' is not always the same */
/* and must not be used anywhere except a few places. This macro is */
/* controlled by the `USE_SQUARED_DISTANCES' macro. It compute squared */
/* distance or actual distance based on `USE_SQUARED_DISTANCES' value. */
/* By using squared distances the performance can be greatly improved */
/* but there is a risk of overflow. Use it wisely. */
#if USE_SQUARED_DISTANCES
#define VECTOR_LENGTH_16D16( v ) ( FT_MulFix( v.x, v.x ) + \
FT_MulFix( v.y, v.y ) )
#else
#define VECTOR_LENGTH_16D16( v ) FT_Vector_Length( &v )
#endif
/**************************************************************************
*
* typedefs
@ -107,9 +139,12 @@
/* [note]: This is a *direction* vector. */
FT_16D16_Vec direction;
/* Unsigned shortest squared distance from the */
/* point to the above `nearest_point'. */
FT_16D16 squared_distance;
/* Unsigned shortest distance from the point to */
/* the above `nearest_point'. */
/* [NOTE]: This can represent both squared as or */
/* actual distance. This is controlled by the */
/* `USE_SQUARED_DISTANCES' macro. */
FT_16D16 distance;
/* Represent weather the `nearest_point' is outside */
/* or inside the contour corresponding to the edge. */
@ -493,7 +528,9 @@
goto Exit;
}
error = FT_Outline_Decompose( outline, &sdf_decompose_funcs, (void*)shape );
error = FT_Outline_Decompose( outline,
&sdf_decompose_funcs,
(void*)shape );
Exit:
return error;
@ -588,7 +625,8 @@
}
FT_TRACE5(( "\n" ));
FT_TRACE5(( "*note: the above values are in 26.6 fixed point format*\n" ));
FT_TRACE5(( "*note: the above values are "
"in 26.6 fixed point format*\n" ));
FT_TRACE5(( "total number of contours = %d\n", num_contours ));
FT_TRACE5(( "total number of edges = %d\n", total_edges ));
FT_TRACE5(( "[sdf] sdf_shape_dump complete\n" ));
@ -925,8 +963,8 @@
FT_16D16 ortho2;
/* if they are not equal return the shorter */
if ( sdf1.squared_distance != sdf2.squared_distance )
return sdf1.squared_distance < sdf2.squared_distance ?
if ( sdf1.distance != sdf2.distance )
return sdf1.distance < sdf2.distance ?
sdf1 : sdf2;
/* if there is not ambiguity in the sign return any */
@ -1091,8 +1129,7 @@
/* assign the output */
out->nearest_point = nearest_point;
out->sign = cross < 0 ? 1 : -1;
out->squared_distance = FT_MulFix( nearest_vector.x, nearest_vector.x ) +
FT_MulFix( nearest_vector.y, nearest_vector.y );
out->distance = VECTOR_LENGTH_16D16( nearest_vector );
out->direction = line_segment;
Exit:
@ -1272,8 +1309,7 @@
dist_vector.x = curve_point.x - p.x;
dist_vector.y = curve_point.y - p.y;
dist = FT_MulFix( dist_vector.x, dist_vector.x ) +
FT_MulFix( dist_vector.y, dist_vector.y );
dist = VECTOR_LENGTH_16D16( dist_vector );
if ( dist < min )
{
@ -1292,7 +1328,7 @@
FT_MulFix( nearest_point.y - p.y, direction.x );
/* assign the values */
out->squared_distance = min;
out->distance = min;
out->nearest_point = nearest_point;
out->sign = cross < 0 ? 1 : -1;
@ -1393,11 +1429,11 @@
(SDF_Edge*)edge_list.head->data,
point, &current_dist ) );
if ( current_dist.squared_distance >= 0 &&
current_dist.squared_distance < min_dist.squared_distance )
if ( current_dist.distance >= 0 &&
current_dist.distance < min_dist.distance )
min_dist = current_dist;
else if ( current_dist.squared_distance ==
min_dist.squared_distance )
else if ( current_dist.distance ==
min_dist.distance )
min_dist = resolve_corner( min_dist, current_dist, point );
edge_list.head = edge_list.head->next;
@ -1458,7 +1494,10 @@
rows = bitmap->rows;
buffer = (FT_Short*)bitmap->buffer;
sp_sq = FT_INT_16D16( spread * spread );
if ( USE_SQUARED_DISTANCES )
sp_sq = FT_INT_16D16( spread * spread );
else
sp_sq = FT_INT_16D16( spread );
if ( width == 0 || rows == 0 )
{
@ -1506,7 +1545,7 @@
(SDF_Contour*)contour_list.head->data,
grid_point, &current_dist ) );
if ( current_dist.squared_distance < min_dist.squared_distance )
if ( current_dist.distance < min_dist.distance )
min_dist = current_dist;
contour_list.head = contour_list.head->next;
@ -1516,14 +1555,15 @@
/* the value to spread to avoid square_root */
/* clamp the values to spread */
if ( min_dist.squared_distance > sp_sq )
min_dist.squared_distance = sp_sq;
if ( min_dist.distance > sp_sq )
min_dist.distance = sp_sq;
/* square_root the values and fit in a 6.10 fixed point */
min_dist.squared_distance = square_root( min_dist.squared_distance );
if ( USE_SQUARED_DISTANCES )
min_dist.distance = square_root( min_dist.distance );
min_dist.squared_distance /= 64; /* convert from 16.16 to 22.10 */
value = min_dist.squared_distance & 0x0000FFFF; /* truncate to 6.10 */
min_dist.distance /= 64; /* convert from 16.16 to 22.10 */
value = min_dist.distance & 0x0000FFFF; /* truncate to 6.10 */
value *= min_dist.sign;
buffer[index] = value;