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* src/sdf/ftbsdf.c (compute_gradient): Use root(2) for the filter.

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Also, use the computed gradient to approximate
the edge distance from a pixel's position according
to the Gustavson's algorithm.
This commit is contained in:
Anuj Verma 2020-07-30 16:46:07 +05:30 committed by anujverma
parent fbbec7c64d
commit aed19e1524
2 changed files with 67 additions and 15 deletions
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7
[GSoC]ChangeLog
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@ -1,3 +1,10 @@
2020-07-30 Anuj Verma <anujv@iitbhilai.ac.in>
* src/sdf/ftbsdf.c (compute_gradient): Use root(2)
for the filter. Also, use the computed gradient
to approximate the edge distance from a pixel's
position according to the Gustavson's algorithm.
2020-07-29 Anuj Verma <anujv@iitbhilai.ac.in>
[sdf -> bsdf] Added function to approximate edge distance.

75
src/sdf/ftbsdf.c
View File

@ -170,6 +170,9 @@
#undef CHECK_NEIGHBOR
static FT_16D16
square_root( FT_16D16 val );
/**************************************************************************
*
* @Function:
@ -193,6 +196,9 @@
{
/* [TODO]: Write proper explanation. */
FT_16D16_Vec g = { 0, 0 };
FT_16D16 dist;
FT_16D16 a1, temp;
FT_16D16 gx, gy;
if ( x <= 0 || x >= w - 1 ||
@ -200,23 +206,61 @@
return g;
g.x = - current[-w - 1].dist -
2 * current[ -1 ].dist -
current[ w - 1].dist +
current[-w + 1].dist +
2 * current[ 1 ].dist +
current[ w + 1].dist;
g.y = - current[-w - 1].dist -
2 * current[ -w ].dist -
current[-w + 1].dist +
current[ w - 1].dist +
2 * current[ w ].dist +
current[ w + 1].dist;
/* compute the gradient */
g.x = - current[-w - 1].dist -
FT_MulFix( current[-1].dist, 92681 ) -
current[ w - 1].dist +
current[-w + 1].dist +
FT_MulFix( current[1].dist, 92681 ) +
current[ w + 1].dist;
g.y = - current[-w - 1].dist -
FT_MulFix( current[-w].dist, 92681 ) -
current[-w + 1].dist +
current[ w - 1].dist +
FT_MulFix( current[w].dist, 92681 ) +
current[ w + 1].dist;
FT_Vector_NormLen( &g );
g.x = FT_MulFix( g.x, ONE / 2 - current->dist );
g.y = FT_MulFix( g.y, ONE / 2 - current->dist );
/* The gradient gives us the direction of the */
/* edge for the current pixel. Once we have the */
/* approximate direction of the edge, we can */
/* approximate the edge distance much better. */
/* [TODO]: Add squared distance support. */
if ( g.x == 0 || g.y == 0 )
dist = ONE / 2 - current->dist;
else
{
gx = g.x;
gy = g.y;
gx = FT_ABS( gx );
gy = FT_ABS( gy );
if ( gx < gy )
{
temp = gx;
gx = gy;
gy = temp;
}
a1 = FT_DivFix( gy, gx ) / 2;
if ( current->dist < a1 )
dist = (( gx + gy ) / 2) -
square_root( 2 * FT_MulFix( gx,
FT_MulFix( gy, current->dist ) ) );
else if ( current->dist < ( ONE - a1 ) )
dist = FT_MulFix( ONE / 2 - current->dist, gx );
else
dist = -(( gx + gy ) / 2) +
square_root( 2 * FT_MulFix( gx,
FT_MulFix( gy, ONE - current->dist ) ) );
}
g.x = FT_MulFix( g.x, dist );
g.y = FT_MulFix( g.y, dist );
return g;
}
@ -265,6 +309,7 @@
}
}
/* [TODO]: Try to combine the above and below loops. */
for ( j = 0; j < worker->rows; j++ )
{
for ( i = 0; i < worker->width; i++ )