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GimpOperationCageTransform: add code to compute the exact source point to handle aliasing.

This commit is contained in:
Michael Muré 2010-08-08 01:34:53 +02:00
parent a68eb9d72d
commit e94d90f4a7
2 changed files with 35 additions and 10 deletions
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44
app/gegl/gimpoperationcagetransform.c
View File

@ -101,7 +101,7 @@ gimp_operation_cage_transform_class_init (GimpOperationCageTransformClass *klass
static void
gimp_operation_cage_transform_init (GimpOperationCageTransform *self)
{
self->format_coords = babl_format_n(babl_type("float"), 2);
}
static void
@ -229,7 +229,6 @@ gimp_operation_cage_transform_interpolate_source_coords_recurs (GimpOperationCa
{
gint xmin, xmax, ymin, ymax;
GeglRectangle rect = {0, 0, 1, 1};
Babl *format = babl_format_n(babl_type("float"), 2);
gfloat *coords;
coords = g_malloc( 2 * sizeof (gfloat));
@ -266,23 +265,48 @@ gimp_operation_cage_transform_interpolate_source_coords_recurs (GimpOperationCa
if (xmin == xmax || ymin == ymax)
return;
/* test if there is only one pixel left in the triangle */
/* test if the triangle is small enough.
* if yes, we compute the coefficient of the barycenter for the pixel (x,y) and see if a pixel is inside (ie the 3 coef have the same sign).
*/
if (xmax - xmin == 1 && ymax - ymin == 1)
{
gfloat a, b, c, denom, x, y;
rect.x = xmax;
rect.y = ymax;
coords[0] = p1_s.x;
coords[1] = p1_s.y;
gegl_buffer_set(out_buf,
&rect,
format,
coords,
GEGL_AUTO_ROWSTRIDE);
x = (gfloat) xmax;
y = (gfloat) ymax;
denom = (p2_d.x - p1_d.x) * p3_d.y + (p1_d.x - p3_d.x) * p2_d.y + (p3_d.x - p2_d.x) * p1_d.y;
a = ((p2_d.x - x) * p3_d.y + (x - p3_d.x) * p2_d.y + (p3_d.x - p2_d.x) * y) / denom;
b = - ((p1_d.x - x) * p3_d.y + (x - p3_d.x) * p1_d.y + (p3_d.x - p1_d.x) * y) / denom;
c = 1.0 - a - b;
/* if a pixel is inside, we compute his source coordinate and set it in the output buffer */
if ((a > 0 && b > 0 && c > 0) || (a < 0 && b < 0 && c < 0))
{
coords[0] = (a * p1_s.x + b * p2_s.x + c * p3_s.x);
coords[1] = (a * p1_s.y + b * p2_s.y + c * p3_s.y);
gegl_buffer_set(out_buf,
&rect,
oct->format_coords,
coords,
GEGL_AUTO_ROWSTRIDE);
}
}
else
{
/* we cut the triangle in 4 sub-triangle and treat it recursively */
/*
* /\
* /__\
* /\ /\
* /__\/__\
*
*/
GimpCoords pm1_d, pm2_d, pm3_d;
GimpCoords pm1_s, pm2_s, pm3_s;

1
app/gegl/gimpoperationcagetransform.h
View File

@ -44,6 +44,7 @@ struct _GimpOperationCageTransform
GeglOperationFilter parent_instance;
GimpCageConfig *config;
Babl *format_coords;
};
struct _GimpOperationCageTransformClass