[PATCH libinput 06/11] util: add a couple of 3x3 matrix helper functions

[Hans de Goede]

Hi,

On 08/27/2014 06:31 AM, Peter Hutterer wrote:
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> ---
>  src/libinput-util.h | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  test/misc.c         |  78 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 178 insertions(+)
> 
> diff --git a/src/libinput-util.h b/src/libinput-util.h
> index 5d366b0..925b86e 100644
> --- a/src/libinput-util.h
> +++ b/src/libinput-util.h
> @@ -25,6 +25,7 @@
>  
>  #include <unistd.h>
>  #include <math.h>
> +#include <string.h>
>  
>  #include "libinput.h"
>  
> @@ -179,4 +180,103 @@ long_set_bit_state(unsigned long *array, int bit, int state)
>  		long_clear_bit(array, bit);
>  }
>  
> +struct matrix {
> +	float val[3][3]; /* [row][col] */
> +};
> +
> +static inline void
> +matrix_init_identity(struct matrix *m)
> +{
> +	memset(m, 0, sizeof(*m));
> +	m->val[0][0] = 1;
> +	m->val[1][1] = 1;
> +	m->val[2][2] = 1;
> +}
> +
> +static inline void
> +matrix_from_farray6(struct matrix *m, const float values[6])
> +{
> +	matrix_init_identity(m);
> +	m->val[0][0] = values[0];
> +	m->val[0][1] = values[1];
> +	m->val[0][2] = values[2];
> +	m->val[1][0] = values[3];
> +	m->val[1][1] = values[4];
> +	m->val[1][2] = values[5];
> +}
> +
> +static inline void
> +matrix_init_scale(struct matrix *m, float sx, float sy)
> +{
> +	matrix_init_identity(m);
> +	m->val[0][0] = sx;
> +	m->val[1][1] = sy;
> +}
> +
> +static inline void
> +matrix_init_translate(struct matrix *m, float x, float y)
> +{
> +	matrix_init_identity(m);
> +	m->val[0][2] = x;
> +	m->val[1][2] = y;
> +}
> +
> +static inline int
> +matrix_is_identity(struct matrix *m)
> +{
> +	return (m->val[0][0] == 1 &&
> +		m->val[0][1] == 0 &&
> +		m->val[0][2] == 0 &&
> +		m->val[1][0] == 0 &&
> +		m->val[1][1] == 1 &&
> +		m->val[1][2] == 0 &&
> +		m->val[2][0] == 0 &&
> +		m->val[2][1] == 0 &&
> +		m->val[2][2] == 1);
> +}
> +
> +static inline void
> +matrix_mult(struct matrix *dest,
> +	    const struct matrix *m1,
> +	    const struct matrix *m2)
> +{
> +	struct matrix m;
> +	int row, col, i;
> +
> +	for (row = 0; row < 3; row++) {
> +		for (col = 0; col < 3; col++) {
> +			double v = 0;
> +			for (i = 0; i < 3; i++) {
> +				v += m1->val[row][i] * m2->val[i][col];
> +			}
> +			m.val[row][col] = v;
> +		}
> +	}
> +
> +	memcpy(dest, &m, sizeof(m));

Why are you storing things in a local matrix first, and not
directly into dest ?


> +}
> +
> +static inline void
> +matrix_mult_vec(struct matrix *m, int *x, int *y)
> +{
> +	int tx, ty;
> +
> +	tx = *x * m->val[0][0] + *y * m->val[0][1] + m->val[0][2];
> +	ty = *x * m->val[1][0] + *y * m->val[1][1] + m->val[1][2];
> +
> +	*x = tx;
> +	*y = ty;
> +}

Idem comment as for patch 5/11.

Otherwise looks good.

Regards,

Hans

> +
> +static inline void
> +matrix_to_farray6(const struct matrix *m, float out[6])
> +{
> +	out[0] = m->val[0][0];
> +	out[1] = m->val[0][1];
> +	out[2] = m->val[0][2];
> +	out[3] = m->val[1][0];
> +	out[4] = m->val[1][1];
> +	out[5] = m->val[1][2];
> +}
> +
>  #endif /* LIBINPUT_UTIL_H */
> diff --git a/test/misc.c b/test/misc.c
> index 983c3f9..1512180 100644
> --- a/test/misc.c
> +++ b/test/misc.c
> @@ -431,6 +431,83 @@ START_TEST(config_status_string)
>  }
>  END_TEST
>  
> +START_TEST(matrix_helpers)
> +{
> +	struct matrix m1, m2, m3;
> +	float f[6] = { 1, 2, 3, 4, 5, 6 };
> +	int x, y;
> +	int row, col;
> +
> +	matrix_init_identity(&m1);
> +
> +	for (row = 0; row < 3; row++) {
> +		for (col = 0; col < 3; col++) {
> +			ck_assert_int_eq(m1.val[row][col],
> +					 (row == col) ? 1 : 0);
> +		}
> +	}
> +	ck_assert(matrix_is_identity(&m1));
> +
> +	matrix_from_farray6(&m2, f);
> +	ck_assert_int_eq(m2.val[0][0], 1);
> +	ck_assert_int_eq(m2.val[0][1], 2);
> +	ck_assert_int_eq(m2.val[0][2], 3);
> +	ck_assert_int_eq(m2.val[1][0], 4);
> +	ck_assert_int_eq(m2.val[1][1], 5);
> +	ck_assert_int_eq(m2.val[1][2], 6);
> +	ck_assert_int_eq(m2.val[2][0], 0);
> +	ck_assert_int_eq(m2.val[2][1], 0);
> +	ck_assert_int_eq(m2.val[2][2], 1);
> +
> +	x = 100;
> +	y = 5;
> +	matrix_mult_vec(&m1, &x, &y);
> +	ck_assert_int_eq(x, 100);
> +	ck_assert_int_eq(y, 5);
> +
> +	matrix_mult(&m3, &m1, &m1);
> +	ck_assert(matrix_is_identity(&m3));
> +
> +	matrix_init_scale(&m2, 2, 4);
> +	ck_assert_int_eq(m2.val[0][0], 2);
> +	ck_assert_int_eq(m2.val[0][1], 0);
> +	ck_assert_int_eq(m2.val[0][2], 0);
> +	ck_assert_int_eq(m2.val[1][0], 0);
> +	ck_assert_int_eq(m2.val[1][1], 4);
> +	ck_assert_int_eq(m2.val[1][2], 0);
> +	ck_assert_int_eq(m2.val[2][0], 0);
> +	ck_assert_int_eq(m2.val[2][1], 0);
> +	ck_assert_int_eq(m2.val[2][2], 1);
> +
> +	matrix_mult_vec(&m2, &x, &y);
> +	ck_assert_int_eq(x, 200);
> +	ck_assert_int_eq(y, 20);
> +
> +	matrix_init_translate(&m2, 10, 100);
> +	ck_assert_int_eq(m2.val[0][0], 1);
> +	ck_assert_int_eq(m2.val[0][1], 0);
> +	ck_assert_int_eq(m2.val[0][2], 10);
> +	ck_assert_int_eq(m2.val[1][0], 0);
> +	ck_assert_int_eq(m2.val[1][1], 1);
> +	ck_assert_int_eq(m2.val[1][2], 100);
> +	ck_assert_int_eq(m2.val[2][0], 0);
> +	ck_assert_int_eq(m2.val[2][1], 0);
> +	ck_assert_int_eq(m2.val[2][2], 1);
> +
> +	matrix_mult_vec(&m2, &x, &y);
> +	ck_assert_int_eq(x, 210);
> +	ck_assert_int_eq(y, 120);
> +
> +	matrix_to_farray6(&m2, f);
> +	ck_assert_int_eq(f[0], 1);
> +	ck_assert_int_eq(f[1], 0);
> +	ck_assert_int_eq(f[2], 10);
> +	ck_assert_int_eq(f[3], 0);
> +	ck_assert_int_eq(f[4], 1);
> +	ck_assert_int_eq(f[5], 100);
> +}
> +END_TEST
> +
>  int main (int argc, char **argv) {
>  	litest_add_no_device("events:conversion", event_conversion_device_notify);
>  	litest_add_no_device("events:conversion", event_conversion_pointer);
> @@ -441,5 +518,6 @@ int main (int argc, char **argv) {
>  	litest_add("device:id", device_ids, LITEST_ANY, LITEST_ANY);
>  	litest_add_no_device("config:status string", config_status_string);
>  
> +	litest_add_no_device("misc:matrix", matrix_helpers);
>  	return litest_run(argc, argv);
>  }
>