/* Worley noise generator.
 *
 * 19/7/16
 *
 * 11/8/16
 * 	- float output
 */

/*

	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 _VipsWorley {
	VipsCreate parent_instance;

	int width;
	int height;
	int cell_size;

	int cells_across;
	int cells_down;

	/* Use this to seed this call of our rng.
	 */
	guint32 seed;
} VipsWorley;

typedef struct _VipsWorleyClass {
	VipsCreateClass parent_class;

} VipsWorleyClass;

G_DEFINE_TYPE(VipsWorley, vips_worley, VIPS_TYPE_CREATE);

#define MAX_FEATURES (10)

typedef struct _Cell {
	/* Cell position, in number of cells. Scale by cell_size to get
	 * absolute image cods.
	 */
	int cell_x;
	int cell_y;

	/* A cell contains 1 to n features.
	 */
	int n_features;

	/* Feature coordinates, in absolute image space.
	 */
	int feature_x[MAX_FEATURES];
	int feature_y[MAX_FEATURES];
} Cell;

typedef struct _Sequence {
	VipsWorley *worley;

	/* The position of the last cell we were in. Use this to avoid
	 * regenerating cells on every pixel lookup.
	 */
	int cell_x;
	int cell_y;

	/* The 3 x 3 grid of cells around the current point.
	 */
	Cell cells[9];

} Sequence;

/* Generate a 3 x 3 grid of cells around a point.
 */
static void
vips_worley_create_cells(VipsWorley *worley,
	Cell cells[9], int cell_x, int cell_y)
{
	int x, y;

	for (y = 0; y < 3; y++)
		for (x = 0; x < 3; x++) {
			Cell *cell = &cells[x + y * 3];

			guint32 seed;
			int value;
			int j;

			/* Can go <0 and >width for edges.
			 */
			cell->cell_x = cell_x + x - 1;
			cell->cell_y = cell_y + y - 1;

			seed = worley->seed;

			/* When we calculate the seed for this cell, we wrap
			 * around so that our output will tessellate.
			 */
			if (cell->cell_x >= worley->cells_across)
				value = 0;
			else if (cell->cell_x < 0)
				value = worley->cells_across - 1;
			else
				value = cell->cell_x;
			seed = vips__random_add(seed, value);

			if (cell->cell_y >= worley->cells_down)
				value = 0;
			else if (cell->cell_y < 0)
				value = worley->cells_down - 1;
			else
				value = cell->cell_y;
			seed = vips__random_add(seed, value);

			/* [1, MAX_FEATURES)
			 */
			cell->n_features = (seed % (MAX_FEATURES - 1)) + 1;

			for (j = 0; j < cell->n_features; j++) {
				seed = vips__random(seed);
				cell->feature_x[j] =
					cell->cell_x * worley->cell_size +
					seed % worley->cell_size;

				seed = vips__random(seed);
				cell->feature_y[j] =
					cell->cell_y * worley->cell_size +
					seed % worley->cell_size;
			}
		}
}

static int
vips_worley_stop(void *vseq, void *a, void *b)
{
	Sequence *seq = (Sequence *) vseq;

	VIPS_FREE(seq);

	return 0;
}

static void *
vips_worley_start(VipsImage *out, void *a, void *b)
{
	VipsWorley *worley = (VipsWorley *) b;

	Sequence *seq;

	if (!(seq = VIPS_NEW(NULL, Sequence)))
		return NULL;

	seq->worley = worley;
	seq->cell_x = -1;
	seq->cell_y = -1;

	return seq;
}

static float
vips_hypot(int x, int y)
{
	/* Faster than hypot() for int args.
	 */
	return sqrt(x * x + y * y);
}

static float
vips_worley_distance(VipsWorley *worley, Cell cells[9], int x, int y)
{
	float distance;

	int i, j;

	distance = worley->cell_size * 1.5;

	for (i = 0; i < 9; i++) {
		Cell *cell = &cells[i];

		for (j = 0; j < cell->n_features; j++) {
			float d = vips_hypot(
				x - cell->feature_x[j],
				y - cell->feature_y[j]);

			distance = VIPS_MIN(distance, d);
		}
	}

	return distance;
}

static int
vips_worley_gen(VipsRegion *out_region,
	void *vseq, void *a, void *b, gboolean *stop)
{
	VipsWorley *worley = (VipsWorley *) a;
	VipsRect *r = &out_region->valid;
	Sequence *seq = (Sequence *) vseq;

	int x, y;

	for (y = 0; y < r->height; y++) {
		float *q = (float *) VIPS_REGION_ADDR(out_region, r->left, r->top + y);

		for (x = 0; x < r->width; x++) {
			int cell_x = (r->left + x) / worley->cell_size;
			int cell_y = (r->top + y) / worley->cell_size;

			if (cell_x != seq->cell_x ||
				cell_y != seq->cell_y) {
				vips_worley_create_cells(worley,
					seq->cells, cell_x, cell_y);
				seq->cell_x = cell_x;
				seq->cell_y = cell_y;
			}

			q[x] = vips_worley_distance(worley, seq->cells,
				r->left + x, r->top + y);
		}
	}

	return 0;
}

static int
vips_worley_build(VipsObject *object)
{
	VipsCreate *create = VIPS_CREATE(object);
	VipsWorley *worley = (VipsWorley *) object;

	if (VIPS_OBJECT_CLASS(vips_worley_parent_class)->build(object))
		return -1;

	/* Be careful if width is a multiple of cell_size.
	 */
	worley->cells_across =
		VIPS_ROUND_UP(worley->width, worley->cell_size) /
		worley->cell_size;
	worley->cells_down =
		VIPS_ROUND_UP(worley->height, worley->cell_size) /
		worley->cell_size;

	vips_image_init_fields(create->out,
		worley->width, worley->height, 1,
		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_worley_start, vips_worley_gen, vips_worley_stop,
			worley, NULL))
		return -1;

	return 0;
}

static void
vips_worley_class_init(VipsWorleyClass *class)
{
	GObjectClass *gobject_class = G_OBJECT_CLASS(class);
	VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS(class);

	gobject_class->set_property = vips_object_set_property;
	gobject_class->get_property = vips_object_get_property;

	vobject_class->nickname = "worley";
	vobject_class->description = _("make a worley noise image");
	vobject_class->build = vips_worley_build;

	VIPS_ARG_INT(class, "width", 2,
		_("Width"),
		_("Image width in pixels"),
		VIPS_ARGUMENT_REQUIRED_INPUT,
		G_STRUCT_OFFSET(VipsWorley, width),
		1, VIPS_MAX_COORD, 1);

	VIPS_ARG_INT(class, "height", 3,
		_("Height"),
		_("Image height in pixels"),
		VIPS_ARGUMENT_REQUIRED_INPUT,
		G_STRUCT_OFFSET(VipsWorley, height),
		1, VIPS_MAX_COORD, 1);

	VIPS_ARG_INT(class, "cell_size", 3,
		_("Cell size"),
		_("Size of Worley cells"),
		VIPS_ARGUMENT_OPTIONAL_INPUT,
		G_STRUCT_OFFSET(VipsWorley, cell_size),
		1, VIPS_MAX_COORD, 256);

	VIPS_ARG_INT(class, "seed", 4,
		_("Seed"),
		_("Random number seed"),
		VIPS_ARGUMENT_OPTIONAL_INPUT,
		G_STRUCT_OFFSET(VipsWorley, seed),
		INT_MIN, INT_MAX, 0);
}

static void
vips_worley_init(VipsWorley *worley)
{
	worley->cell_size = 256;
	worley->seed = UINT_MAX * g_random_double();
}

/**
 * vips_worley:
 * @out: (out): output image
 * @width: horizontal size
 * @height: vertical size
 * @...: %NULL-terminated list of optional named arguments
 *
 * Optional arguments:
 *
 * * @cell_size: %gint, size of Worley cells
 *
 * Create a one-band float image of Worley noise. See:
 *
 * https://en.wikipedia.org/wiki/Worley_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.
 *
 * See also: vips_perlin(), vips_fractsurf(), vips_gaussnoise().
 *
 * Returns: 0 on success, -1 on error
 */
int
vips_worley(VipsImage **out, int width, int height, ...)
{
	va_list ap;
	int result;

	va_start(ap, height);
	result = vips_call_split("worley", ap, out, width, height);
	va_end(ap);

	return result;
}
