/* Graphics_altitude.c
 *
 * Copyright (C) 1992-2002 Paul Boersma
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 * pb 2000/09/21
 * pb 2002/03/07 GPL
 */

#include "Graphics.h"

static int empty (float **data, int **right, int **below, long row1, long col1, double height, int row, int col, int ori) {
	if (ori == 3) { row ++; ori = 1; } else if (ori == 2) { col ++; ori = 4; }
	if (ori == 1)
		return (data [row] [col] < height) != (data [row] [col + 1] < height) &&
			! right [row - row1] [col - col1];
	else /* ori == 4 */
		return (data [row] [col] < height) != (data [row + 1] [col] < height) &&
			! below [row - row1] [col - col1];
}

#define MAXALTSIDE  50
#define MAXALTPATH  (2 * MAXALTSIDE * (MAXALTSIDE - 1) + 2)

static long numberOfPoints;
static long row1, row2, col1, col2;
static int **right, **below;
static float *x, *y;
static int closed;
static double dx, dy, xoff, yoff;

static int note (float **z, double height, int row, int col, int ori, int forget) {
	++ numberOfPoints;
	Melder_assert (numberOfPoints <= MAXALTPATH);
	if (ori == 3) { row ++; ori = 1; } else if (ori == 2) { col ++; ori = 4; }
	if (ori == 1) {
		if (forget) right [row - row1] [col - col1] = 1;
		x [numberOfPoints] = xoff +
			(col + (height - z [row] [col]) / (z [row] [col + 1] - z [row] [col])) * dx;
		y [numberOfPoints] = yoff + row * dy;
	} else {   /* ori == 4 */
		if (forget) below [row - row1] [col - col1] = 1;
		x [numberOfPoints] = xoff + col * dx;
		y [numberOfPoints] = yoff +
			(row + (height - z [row] [col]) / (z [row + 1] [col] - z [row] [col])) * dy;
	}
	return 1;
}

static void makeContour (Graphics graphics, float **z, double height, int row0, int col0, int ori0) {
	int row, col, ori, clockwise = 0, edge = 0;
	numberOfPoints = 0;
	row = row0; col = col0; ori = ori0;
	note (z, height, row0, col0, ori0, 0);
	do {
		clockwise = ! (ori & 1);
		do {   /* Preference for contours perpendicular to x == y. */
			ori = (clockwise ? ori : ori + 2) % 4 + 1;
		} while (! empty (z, right, below, row1, col1, height, row, col, ori));
		if (! closed) switch (ori) {
			case 1: edge = row == row1; break;
			case 2: edge = col == col2 - 1; break;
			case 3: edge = row == row2 - 1; break;
			case 4: edge = col == col1; break;
		}
		if (! edge) {
			switch (ori) {
				case 1: row --; break;
				case 2: col ++; break;
				case 3: row ++; break;
				case 4: col --; break;
			}
			ori = (ori + 1) % 4 + 1;
		}
		if (! note (z, height, row, col, ori, 1)) return;
	}
	while (edge == 0 && (row != row0 || col != col0 || ori != ori0));
	if (closed) note (z, height, row0, col0, ori0, 1);   /* Close the contour. */
	Graphics_polyline (graphics, numberOfPoints, & x [1], & y [1]);
}

static void smallAlt (Graphics graphics, float **z, double height) {
	int row, col;
	for (row = 0; row < MAXALTSIDE; row ++) for (col = 0; col < MAXALTSIDE; col ++)
		right [row] [col] = below [row] [col] = 0;

	/* Find all the edge contours of this border value. */

	closed = 0;
	for (col = col1; col < col2; col ++)
		if (empty (z, right, below, row1, col1, height, row1, col, 1))
			makeContour (graphics, z, height, row1, col, 1);
	for (row = row1; row < row2; row ++)
		if (empty (z, right, below, row1, col1, height, row, col2 - 1, 2))
			makeContour (graphics, z, height, row, col2 - 1, 2);
	for (col = col2 - 1; col >= col1; col --)
		if (empty (z, right, below, row1, col1, height, row2 - 1, col, 3))
			makeContour (graphics, z, height, row2 - 1, col, 3);
	for (row = row2 - 1; row >= row1; row --)
		if (empty (z, right, below, row1, col1, height, row, col1, 4))
			makeContour (graphics, z, height, row, col1, 4);

	/* Find all the closed contours of this border value. */

	closed = 1;
	for (row = row1 + 1; row < row2; row ++)
		for (col = col1; col < col2; col ++)
			if (empty (z, right, below, row1, col1, height, row, col, 1))
				makeContour (graphics, z, height, row, col, 1);
	for (col = col1 + 1; col < col2; col ++)
		for (row = row1; row < row2; row ++)
			if (empty (z, right, below, row1, col1, height, row, col, 4))
				makeContour (graphics, z, height, row, col, 4);
}

void Graphics_contour (I, float **z,
	long ix1, long ix2, double x1WC, double x2WC,
	long iy1, long iy2, double y1WC, double y2WC,
	double height)
{
	iam (Graphics);
	if (ix2 <= ix1 || iy2 <= iy1) return;
	dx = (x2WC - x1WC) / (ix2 - ix1);
	dy = (y2WC - y1WC) / (iy2 - iy1);
	xoff = x1WC - ix1 * dx;
	yoff = y1WC - iy1 * dy;
	if (! right) {   /* Static! */
		right = NUMimatrix (0, MAXALTSIDE - 1, 0, MAXALTSIDE - 1);
		below = NUMimatrix (0, MAXALTSIDE - 1, 0, MAXALTSIDE - 1);
		x = NUMfvector (1, MAXALTPATH);
		y = NUMfvector (1, MAXALTPATH);
		if (! y) {
			right = NULL;
			Melder_flushError ("Graphics_altitude: not enough memory.");
			return;
		}
	}
	for (row1 = iy1; row1 < iy2; row1 += MAXALTSIDE - 1)
		for (col1 = ix1; col1 < ix2; col1 += MAXALTSIDE - 1) {
			if ((row2 = row1 + (MAXALTSIDE - 1)) > iy2) row2 = iy2;
			if ((col2 = col1 + (MAXALTSIDE - 1)) > ix2) col2 = ix2;
			smallAlt (me, z, height);
		}
}

void Graphics_altitude (I, float **z,
	long ix1, long ix2, double x1WC, double x2WC,
	long iy1, long iy2, double y1WC, double y2WC,
	int numberOfBorders, float borders [])
{
	iam (Graphics);
	int iborder;
	if (ix2 <= ix1 || iy2 <= iy1) return;
	dx = (x2WC - x1WC) / (ix2 - ix1);
	dy = (y2WC - y1WC) / (iy2 - iy1);
	xoff = x1WC - ix1 * dx;
	yoff = y1WC - iy1 * dy;
	if (! right) {   /* Static! */
		right = NUMimatrix (0, MAXALTSIDE - 1, 0, MAXALTSIDE - 1);
		below = NUMimatrix (0, MAXALTSIDE - 1, 0, MAXALTSIDE - 1);
		x = NUMfvector (1, MAXALTPATH);
		y = NUMfvector (1, MAXALTPATH);
		if (! y) {
			right = NULL;
			Melder_flushError ("Graphics_altitude: not enough memory.");
			return;
		}
	}
	for (row1 = iy1; row1 < iy2; row1 += MAXALTSIDE - 1)
		for (col1 = ix1; col1 < ix2; col1 += MAXALTSIDE - 1) {
			if ((row2 = row1 + (MAXALTSIDE - 1)) > iy2) row2 = iy2;
			if ((col2 = col1 + (MAXALTSIDE - 1)) > ix2) col2 = ix2;
			for (iborder = 1; iborder <= numberOfBorders; iborder ++) {
				smallAlt (me, z, borders [iborder]);
			}
		}
}

/* End of file Graphics_altitude.c */
