weston/src/matrix.c

/*
 * Copyright © 2011 Intel Corporation
 *
 * Permission to use, copy, modify, distribute, and sell this software and
 * its documentation for any purpose is hereby granted without fee, provided
 * that the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of the copyright holders not be used in
 * advertising or publicity pertaining to distribution of the software
 * without specific, written prior permission.  The copyright holders make
 * no representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
 * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
 * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
 * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <string.h>
#include <stdlib.h>
#include <GLES2/gl2.h>
#include <wayland-server.h>

#include "matrix.h"

/*
 * Matrices are stored in column-major order, that is the array indices are:
 *  0  4  8 12
 *  1  5  9 13
 *  2  6 10 14
 *  3  7 11 15
 */

WL_EXPORT void
weston_matrix_init(struct weston_matrix *matrix)
{
	static const struct weston_matrix identity = {
		{ 1, 0, 0, 0,  0, 1, 0, 0,  0, 0, 1, 0,  0, 0, 0, 1 }
	};

	memcpy(matrix, &identity, sizeof identity);
}

/* m <- n * m, that is, m is multiplied on the LEFT. */
WL_EXPORT void
weston_matrix_multiply(struct weston_matrix *m, const struct weston_matrix *n)
{
	struct weston_matrix tmp;
	const GLfloat *row, *column;
	div_t d;
	int i, j;

	for (i = 0; i < 16; i++) {
		tmp.d[i] = 0;
		d = div(i, 4);
		row = m->d + d.quot * 4;
		column = n->d + d.rem;
		for (j = 0; j < 4; j++)
			tmp.d[i] += row[j] * column[j * 4];
	}
	memcpy(m, &tmp, sizeof tmp);
}

WL_EXPORT void
weston_matrix_translate(struct weston_matrix *matrix, GLfloat x, GLfloat y, GLfloat z)
{
	struct weston_matrix translate = {
		{ 1, 0, 0, 0,  0, 1, 0, 0,  0, 0, 1, 0,  x, y, z, 1 }
	};

	weston_matrix_multiply(matrix, &translate);
}

WL_EXPORT void
weston_matrix_scale(struct weston_matrix *matrix, GLfloat x, GLfloat y, GLfloat z)
{
	struct weston_matrix scale = {
		{ x, 0, 0, 0,  0, y, 0, 0,  0, 0, z, 0,  0, 0, 0, 1 }
	};

	weston_matrix_multiply(matrix, &scale);
}

/* v <- m * v */
WL_EXPORT void
weston_matrix_transform(struct weston_matrix *matrix, struct weston_vector *v)
{
	int i, j;
	struct weston_vector t;

	for (i = 0; i < 4; i++) {
		t.f[i] = 0;
		for (j = 0; j < 4; j++)
			t.f[i] += v->f[j] * matrix->d[i + j * 4];
	}

	*v = t;
}

WL_EXPORT int
weston_matrix_invert(struct weston_matrix *inverse,
		     const struct weston_matrix *matrix)
{
	return -1; /* fail */
}