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compositor: simplify the matrix inversion API

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The compositor will likely do an order of magnitude less matrix
inversions than point transformations with an inverse, hence we do not
really need the optimised path for single-shot invert-and-transform.

Expose only the computing of the explicit inverse matrix in the API.

However, the matrix inversion tests need access to the internal
functions. Designate a unit test build by #defining UNIT_TEST, and
export the internal functions in that case.

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>
dev
Pekka Paalanen 13 years ago
parent 1ef94c8742
commit d1f0ab6343
6 changed files with 81 additions and 67 deletions
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  1. 2
      src/compositor.c
  2. 2
      src/compositor.h
  3. 61
      src/matrix.c
  4. 21
      src/matrix.h
  5. 2
      tests/Makefile.am
  6. 60
      tests/matrix-test.c

2
src/compositor.c
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@ -545,7 +545,7 @@ static void
weston_surface_update_transform(struct weston_surface *surface)
{
struct weston_matrix *matrix = &surface->transform.matrix;
struct weston_inverse_matrix *inverse = &surface->transform.inverse;
struct weston_matrix *inverse = &surface->transform.inverse;
struct weston_transform *tform;
if (!surface->transform.dirty)

2
src/compositor.h
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@ -230,7 +230,7 @@ struct weston_surface {
/* derived state, set up by weston_surface_update_transform */
struct weston_matrix matrix;
struct weston_inverse_matrix inverse;
struct weston_matrix inverse;
int enabled;
} transform;

61
src/matrix.c
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@ -29,6 +29,7 @@
#include "matrix.h"
/*
* Matrices are stored in column-major order, that is the array indices are:
* 0 4 8 12
@ -116,6 +117,16 @@ swap_rows(double *a, double *b)
}
}
static inline void
swap_unsigned(unsigned *a, unsigned *b)
{
unsigned tmp;
tmp = *a;
*a = *b;
*b = tmp;
}
static inline unsigned
find_pivot(double *column, unsigned k)
{
@ -133,16 +144,15 @@ find_pivot(double *column, unsigned k)
* LU decomposition, forward and back substitution: Chapter 3.
*/
WL_EXPORT int
weston_matrix_invert(struct weston_inverse_matrix *inverse,
const struct weston_matrix *matrix)
MATRIX_TEST_EXPORT inline int
matrix_invert(double *A, unsigned *p, const struct weston_matrix *matrix)
{
double A[16];
unsigned p[4] = { 0, 1, 2, 3 };
unsigned i, j, k;
unsigned pivot;
double pv;
for (i = 0; i < 4; ++i)
p[i] = i;
for (i = 16; i--; )
A[i] = matrix->d[i];
@ -150,9 +160,7 @@ weston_matrix_invert(struct weston_inverse_matrix *inverse,
for (k = 0; k < 4; ++k) {
pivot = find_pivot(&A[k * 4], k);
if (pivot != k) {
unsigned tmp = p[k];
p[k] = p[pivot];
p[pivot] = tmp;
swap_unsigned(&p[k], &p[pivot]);
swap_rows(&A[k], &A[pivot]);
}
@ -168,30 +176,25 @@ weston_matrix_invert(struct weston_inverse_matrix *inverse,
}
}
memcpy(inverse->LU, A, sizeof(A));
memcpy(inverse->p, p, sizeof(p));
return 0;
}
WL_EXPORT void
weston_matrix_inverse_transform(struct weston_inverse_matrix *inverse,
struct weston_vector *v)
MATRIX_TEST_EXPORT inline void
inverse_transform(const double *LU, const unsigned *p, GLfloat *v)
{
/* Solve A * x = v, when we have P * A = L * U.
* P * A * x = P * v => L * U * x = P * v
* Let U * x = b, then L * b = P * v.
*/
unsigned *p = inverse->p;
double *LU = inverse->LU;
double b[4];
unsigned j;
/* Forward substitution, column version, solves L * b = P * v */
/* The diagonal of L is all ones, and not explicitly stored. */
b[0] = v->f[p[0]];
b[1] = (double)v->f[p[1]] - b[0] * LU[1 + 0 * 4];
b[2] = (double)v->f[p[2]] - b[0] * LU[2 + 0 * 4];
b[3] = (double)v->f[p[3]] - b[0] * LU[3 + 0 * 4];
b[0] = v[p[0]];
b[1] = (double)v[p[1]] - b[0] * LU[1 + 0 * 4];
b[2] = (double)v[p[2]] - b[0] * LU[2 + 0 * 4];
b[3] = (double)v[p[3]] - b[0] * LU[3 + 0 * 4];
b[2] -= b[1] * LU[2 + 1 * 4];
b[3] -= b[1] * LU[3 + 1 * 4];
b[3] -= b[2] * LU[3 + 2 * 4];
@ -225,5 +228,23 @@ weston_matrix_inverse_transform(struct weston_inverse_matrix *inverse,
/* the result */
for (j = 0; j < 4; ++j)
v->f[j] = b[j];
v[j] = b[j];
}
WL_EXPORT int
weston_matrix_invert(struct weston_matrix *inverse,
const struct weston_matrix *matrix)
{
double LU[16]; /* column-major */
unsigned perm[4]; /* permutation */
unsigned c;
if (matrix_invert(LU, perm, matrix) < 0)
return -1;
weston_matrix_init(inverse);
for (c = 0; c < 4; ++c)
inverse_transform(LU, perm, &inverse->d[c * 4]);
return 0;
}

21
src/matrix.h
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@ -28,11 +28,6 @@ struct weston_matrix {
GLfloat d[16];
};
struct weston_inverse_matrix {
double LU[16]; /* column-major */
unsigned p[4]; /* permutation */
};
struct weston_vector {
GLfloat f[4];
};
@ -50,10 +45,20 @@ void
weston_matrix_transform(struct weston_matrix *matrix, struct weston_vector *v);
int
weston_matrix_invert(struct weston_inverse_matrix *inverse,
weston_matrix_invert(struct weston_matrix *inverse,
const struct weston_matrix *matrix);
#ifdef UNIT_TEST
# define MATRIX_TEST_EXPORT WL_EXPORT
int
matrix_invert(double *A, unsigned *p, const struct weston_matrix *matrix);
void
weston_matrix_inverse_transform(struct weston_inverse_matrix *inverse,
struct weston_vector *v);
inverse_transform(const double *LU, const unsigned *p, GLfloat *v);
#else
# define MATRIX_TEST_EXPORT static
#endif
#endif /* WESTON_MATRIX_H */

2
tests/Makefile.am
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@ -6,7 +6,7 @@ endif
AM_CFLAGS = $(GCC_CFLAGS)
AM_CPPFLAGS = -I../src
AM_CPPFLAGS = -I../src -DUNIT_TEST
matrix_test_SOURCES = \
matrix-test.c \

60
tests/matrix-test.c
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@ -30,6 +30,11 @@
#include "matrix.h"
struct inverse_matrix {
double LU[16]; /* column-major */
unsigned perm[4]; /* permutation */
};
static struct timespec begin_time;
static void
@ -81,9 +86,9 @@ determinant(const struct weston_matrix *m)
}
static void
print_permutation_matrix(const struct weston_inverse_matrix *m)
print_permutation_matrix(const struct inverse_matrix *m)
{
const unsigned *p = m->p;
const unsigned *p = m->perm;
const char *row[4] = {
"1 0 0 0\n",
"0 1 0 0\n",
@ -95,7 +100,7 @@ print_permutation_matrix(const struct weston_inverse_matrix *m)
}
static void
print_LU_decomposition(const struct weston_inverse_matrix *m)
print_LU_decomposition(const struct inverse_matrix *m)
{
unsigned r, c;
@ -128,7 +133,7 @@ print_LU_decomposition(const struct weston_inverse_matrix *m)
}
static void
print_inverse_data_matrix(const struct weston_inverse_matrix *m)
print_inverse_data_matrix(const struct inverse_matrix *m)
{
unsigned r, c;
@ -140,7 +145,7 @@ print_inverse_data_matrix(const struct weston_inverse_matrix *m)
printf("permutation: ");
for (r = 0; r < 4; ++r)
printf(" %u", m->p[r]);
printf(" %u", m->perm[r]);
printf("\n");
}
@ -175,22 +180,6 @@ randomize_matrix(struct weston_matrix *m)
#endif
}
static void
invert_matrix(struct weston_matrix *m)
{
struct weston_inverse_matrix q;
unsigned i;
if (weston_matrix_invert(&q, m) != 0) {
m->d[0] = NAN;
return;
}
for (i = 0; i < 4; ++i)
weston_matrix_inverse_transform(&q,
(struct weston_vector *)&m->d[i * 4]);
}
/* Take a matrix, compute inverse, multiply together
* and subtract the identity matrix to get the error matrix.
* Return the largest absolute value from the error matrix.
@ -199,15 +188,14 @@ static double
test_inverse(struct weston_matrix *m)
{
unsigned i;
struct weston_inverse_matrix q;
struct inverse_matrix q;
double errsup = 0.0;
if (weston_matrix_invert(&q, m) != 0)
if (matrix_invert(q.LU, q.perm, m) != 0)
return INFINITY;
for (i = 0; i < 4; ++i)
weston_matrix_inverse_transform(&q,
(struct weston_vector *)&m->d[i * 4]);
inverse_transform(q.LU, q.perm, &m->d[i * 4]);
m->d[0] -= 1.0f;
m->d[5] -= 1.0f;
@ -309,21 +297,21 @@ static void __attribute__((noinline))
test_loop_speed_inversetransform(void)
{
struct weston_matrix m;
struct weston_inverse_matrix inv;
struct inverse_matrix inv;
struct weston_vector v = { { 0.5, 0.5, 0.5, 1.0 } };
unsigned long count = 0;
double t;
printf("\nRunning 3 s test on weston_matrix_inverse_transform()...\n");
printf("\nRunning 3 s test on inverse_transform()...\n");
weston_matrix_init(&m);
weston_matrix_invert(&inv, &m);
matrix_invert(inv.LU, inv.perm, &m);
running = 1;
alarm(3);
reset_timer();
while (running) {
weston_matrix_inverse_transform(&inv, &v);
inverse_transform(inv.LU, inv.perm, v.f);
count++;
}
t = read_timer();
@ -336,11 +324,11 @@ static void __attribute__((noinline))
test_loop_speed_invert(void)
{
struct weston_matrix m;
struct weston_inverse_matrix inv;
struct inverse_matrix inv;
unsigned long count = 0;
double t;
printf("\nRunning 3 s test on weston_matrix_invert()...\n");
printf("\nRunning 3 s test on matrix_invert()...\n");
weston_matrix_init(&m);
@ -348,7 +336,7 @@ test_loop_speed_invert(void)
alarm(3);
reset_timer();
while (running) {
weston_matrix_invert(&inv, &m);
matrix_invert(inv.LU, inv.perm, &m);
count++;
}
t = read_timer();
@ -364,7 +352,7 @@ test_loop_speed_invert_explicit(void)
unsigned long count = 0;
double t;
printf("\nRunning 3 s test on computing the explicit inverse matrix...\n");
printf("\nRunning 3 s test on weston_matrix_invert()...\n");
weston_matrix_init(&m);
@ -372,7 +360,7 @@ test_loop_speed_invert_explicit(void)
alarm(3);
reset_timer();
while (running) {
invert_matrix(&m);
weston_matrix_invert(&m, &m);
count++;
}
t = read_timer();
@ -385,7 +373,7 @@ int main(void)
{
struct sigaction ding;
struct weston_matrix M;
struct weston_inverse_matrix Q;
struct inverse_matrix Q;
int ret;
double errsup;
double det;
@ -402,7 +390,7 @@ int main(void)
M.d[2] = 6.0; M.d[6] = 18.0; M.d[10] = -12; M.d[14] = 0.0;
M.d[3] = 0.0; M.d[7] = 0.0; M.d[11] = 0.0; M.d[15] = 1.0;
ret = weston_matrix_invert(&Q, &M);
ret = matrix_invert(Q.LU, Q.perm, &M);
printf("ret = %d\n", ret);
printf("det = %g\n\n", determinant(&M));

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