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libvips/libvips/create/perlin.c

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/* Perlin noise generator.
*
* 24/7/16
*/
/*
This file is part of VIPS.
VIPS 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 program 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 program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
/*
#define VIPS_DEBUG
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <glib/gi18n-lib.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <vips/vips.h>
#include "pcreate.h"
typedef struct _VipsPerlin {
VipsCreate parent_instance;
int width;
int height;
int cell_size;
gboolean uchar;
int cells_across;
int cells_down;
/* Use this to seed this call of our rng.
*/
guint32 seed;
} VipsPerlin;
typedef struct _VipsPerlinClass {
VipsCreateClass parent_class;
} VipsPerlinClass;
G_DEFINE_TYPE( VipsPerlin, vips_perlin, VIPS_TYPE_CREATE );
/* cos and sin from an angle in 0 - 255.
*/
float vips_perlin_cos[256];
float vips_perlin_sin[256];
typedef struct _Sequence {
VipsPerlin *perlin;
/* The position of the last cell we were in. Use this to avoid
* regenerating vectors on every pixel lookup.
*/
int cell_x;
int cell_y;
/* The 2 x 2 grid of unit vectors, with cell_x/cell_y as the top left.
*/
float gx[4];
float gy[4];
} Sequence;
/* Generate a 3 x 3 grid of cells around a point.
*/
static void
vips_perlin_create_cells( VipsPerlin *perlin,
float gx[4], float gy[4], int cell_x, int cell_y )
{
int x, y;
for( y = 0; y < 2; y++ )
for( x = 0; x < 2; x++ ) {
int ci = x + y * 2;
guint32 seed;
int cx;
int cy;
int angle;
seed = perlin->seed;
cx = cell_x + x;
cy = cell_y + y;
/* When we calculate the seed for this cell, we wrap
* around so that our output will tesselate.
*/
if( cy >= perlin->cells_down )
cy = 0;
seed = vips__random_add( seed, cy );
if( cx >= perlin->cells_across )
cx = 0;
seed = vips__random_add( seed, cx );
angle = (seed ^ (seed >> 8) ^ (seed >> 16)) & 0xff;
gx[ci] = vips_perlin_cos[angle];
gy[ci] = vips_perlin_sin[angle];
}
}
static int
vips_perlin_stop( void *vseq, void *a, void *b )
{
Sequence *seq = (Sequence *) vseq;
VIPS_FREE( seq );
return( 0 );
}
static void *
vips_perlin_start( VipsImage *out, void *a, void *b )
{
VipsPerlin *perlin = (VipsPerlin *) b;
Sequence *seq;
if( !(seq = VIPS_NEW( NULL, Sequence )) )
return( NULL );
seq->perlin = perlin;
seq->cell_x = -1;
seq->cell_y = -1;
return( seq );
}
/* Smooth linear interpolation, 0 <= x <= 1.
*
* https://en.wikipedia.org/wiki/Smoothstep
*/
static float
smootherstep( float x )
{
return( x * x * x * (x * (x * 6 - 15) + 10) );
}
static int
vips_perlin_gen( VipsRegion *or, void *vseq, void *a, void *b,
gboolean *stop )
{
VipsPerlin *perlin = (VipsPerlin *) a;
VipsRect *r = &or->valid;
Sequence *seq = (Sequence *) vseq;
int x, y;
for( y = 0; y < r->height; y++ ) {
float *fq = (float *)
VIPS_REGION_ADDR( or, r->left, r->top + y );
VipsPel *q = (VipsPel *) fq;
for( x = 0; x < r->width; x++ ) {
int cs = perlin->cell_size;
int cell_x = (r->left + x) / cs;
int cell_y = (r->top + y) / cs;
float dx = (x + r->left - cell_x * cs) / (float) cs;
float dy = (y + r->top - cell_y * cs) / (float) cs;
float sx = smootherstep( dx );
float sy = smootherstep( dy );
float n0, n1;
float ix0, ix1;
float p;
if( cell_x != seq->cell_x ||
cell_y != seq->cell_y ) {
vips_perlin_create_cells( perlin,
seq->gx, seq->gy, cell_x, cell_y );
seq->cell_x = cell_x;
seq->cell_y = cell_y;
}
n0 = -dx * seq->gx[0] + -dy * seq->gy[0];
n1 = (1 - dx) * seq->gx[1] + -dy * seq->gy[1];
ix0 = n0 + sx * (n1 - n0);
n0 = -dx * seq->gx[2] + (1 - dy) * seq->gy[2];
n1 = (1 - dx) * seq->gx[3] + (1 - dy) * seq->gy[3];
ix1 = n0 + sx * (n1 - n0);
p = ix0 + sy * (ix1 - ix0);
if( perlin->uchar )
q[x] = 128 * p + 128;
else
fq[x] = p;
}
}
return( 0 );
}
static int
vips_perlin_build( VipsObject *object )
{
VipsCreate *create = VIPS_CREATE( object );
VipsPerlin *perlin = (VipsPerlin *) object;
if( VIPS_OBJECT_CLASS( vips_perlin_parent_class )->build( object ) )
return( -1 );
/* Be careful if width is a multiple of cell_size.
*/
perlin->cells_across =
VIPS_ROUND_UP( perlin->width, perlin->cell_size ) /
perlin->cell_size;
perlin->cells_down =
VIPS_ROUND_UP( perlin->height, perlin->cell_size ) /
perlin->cell_size;
vips_image_init_fields( create->out,
perlin->width, perlin->height, 1,
perlin->uchar ? VIPS_FORMAT_UCHAR : VIPS_FORMAT_FLOAT,
VIPS_CODING_NONE, VIPS_INTERPRETATION_MULTIBAND,
1.0, 1.0 );
if( vips_image_pipelinev( create->out, VIPS_DEMAND_STYLE_ANY, NULL ) ||
vips_image_generate( create->out,
vips_perlin_start, vips_perlin_gen, vips_perlin_stop,
perlin, NULL ) )
return( -1 );
return( 0 );
}
static void *
vips_perlin_make_tables( void *client )
{
int i;
for( i = 0; i < 256; i++ ) {
double angle = 2 * VIPS_PI * i / 256.0;
vips_perlin_cos[i] = cos( angle );
vips_perlin_sin[i] = sin( angle );
}
return( NULL );
}
static void
vips_perlin_class_init( VipsPerlinClass *class )
{
GObjectClass *gobject_class = G_OBJECT_CLASS( class );
VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
static GOnce once = G_ONCE_INIT;
VIPS_ONCE( &once, vips_perlin_make_tables, NULL );
gobject_class->set_property = vips_object_set_property;
gobject_class->get_property = vips_object_get_property;
vobject_class->nickname = "perlin";
vobject_class->description = _( "make a perlin noise image" );
vobject_class->build = vips_perlin_build;
VIPS_ARG_INT( class, "width", 2,
_( "Width" ),
_( "Image width in pixels" ),
VIPS_ARGUMENT_REQUIRED_INPUT,
G_STRUCT_OFFSET( VipsPerlin, width ),
1, VIPS_MAX_COORD, 1 );
VIPS_ARG_INT( class, "height", 3,
_( "Height" ),
_( "Image height in pixels" ),
VIPS_ARGUMENT_REQUIRED_INPUT,
G_STRUCT_OFFSET( VipsPerlin, height ),
1, VIPS_MAX_COORD, 1 );
VIPS_ARG_INT( class, "cell_size", 3,
_( "Cell size" ),
_( "Size of Perlin cells" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsPerlin, cell_size ),
1, VIPS_MAX_COORD, 256 );
VIPS_ARG_BOOL( class, "uchar", 4,
_( "Uchar" ),
_( "Output an unsigned char image" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsPerlin, uchar ),
FALSE );
VIPS_ARG_INT( class, "seed", 5,
_( "Seed" ),
_( "Random number seed" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsPerlin, seed ),
INT_MIN, INT_MAX, 0 );
}
static void
vips_perlin_init( VipsPerlin *perlin )
{
perlin->cell_size = 256;
perlin->seed = UINT_MAX * g_random_double();
}
/**
* vips_perlin:
* @out: (out): output image
* @width: horizontal size
* @height: vertical size
* @...: %NULL-terminated list of optional named arguments
*
* Optional arguments:
*
* * @cell_size: %gint, size of Perlin cells
* * @uchar: output a uchar image
*
* Create a one-band float image of Perlin noise. See:
*
* https://en.wikipedia.org/wiki/Perlin_noise
*
* Use @cell_size to set the size of the cells from which the image is
* constructed. The default is 256 x 256.
*
* If @width and @height are multiples of @cell_size, the image will tessellate.
*
* Normally, output pixels are #VIPS_FORMAT_FLOAT in the range [-1, +1]. Set
* @uchar to output a uchar image with pixels in [0, 255].
*
* See also: vips_worley(), vips_fractsurf(), vips_gaussnoise().
*
* Returns: 0 on success, -1 on error
*/
int
vips_perlin( VipsImage **out, int width, int height, ... )
{
va_list ap;
int result;
va_start( ap, height );
result = vips_call_split( "perlin", ap, out, width, height );
va_end( ap );
return( result );
}
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