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avfilter/vf_v360: use quaternions for rotation 

Fixes gimbal lock issues, and round-off errors.
This commit is contained in:
Paul B Mahol 2020-10-06 13:51:52 +02:00
parent a48adcd136
commit a086b73e1f
2 changed files with 56 additions and 46 deletions
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2
libavfilter/v360.h
View File

@ -150,7 +150,7 @@ typedef struct V360Context {
float flat_range[2];
float iflat_range[2];
float rot_mat[3][3];
float rot_quaternion[2][4];
float output_mirror_modifier[3];

100
libavfilter/vf_v360.c
View File

@ -3863,73 +3863,76 @@ static int xyz_to_octahedron(const V360Context *s,
return 1;
}
static void multiply_matrix(float c[3][3], const float a[3][3], const float b[3][3])
static void multiply_quaternion(float c[4], const float a[4], const float b[4])
{
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
float sum = 0.f;
c[0] = a[0] * b[0] - a[1] * b[1] - a[2] * b[2] - a[3] * b[3];
c[1] = a[1] * b[0] + a[0] * b[1] + a[2] * b[3] - a[3] * b[2];
c[2] = a[2] * b[0] + a[0] * b[2] + a[3] * b[1] - a[1] * b[3];
c[3] = a[3] * b[0] + a[0] * b[3] + a[1] * b[2] - a[2] * b[1];
}
for (int k = 0; k < 3; k++)
sum += a[i][k] * b[k][j];
c[i][j] = sum;
}
}
static void conjugate_quaternion(float d[4], const float q[4])
{
d[0] = q[0];
d[1] = -q[1];
d[2] = -q[2];
d[3] = -q[3];
}
/**
* Calculate rotation matrix for yaw/pitch/roll angles.
* Calculate rotation quaternion for yaw/pitch/roll angles.
*/
static inline void calculate_rotation_matrix(float yaw, float pitch, float roll,
float rot_mat[3][3],
const int rotation_order[3])
static inline void calculate_rotation(float yaw, float pitch, float roll,
float rot_quaternion[2][4],
const int rotation_order[3])
{
const float yaw_rad = yaw * M_PI / 180.f;
const float pitch_rad = pitch * M_PI / 180.f;
const float roll_rad = roll * M_PI / 180.f;
const float sin_yaw = sinf(yaw_rad);
const float cos_yaw = cosf(yaw_rad);
const float sin_pitch = sinf(pitch_rad);
const float cos_pitch = cosf(pitch_rad);
const float sin_roll = sinf(roll_rad);
const float cos_roll = cosf(roll_rad);
const float sin_yaw = sinf(yaw_rad * 0.5f);
const float cos_yaw = cosf(yaw_rad * 0.5f);
const float sin_pitch = sinf(pitch_rad * 0.5f);
const float cos_pitch = cosf(pitch_rad * 0.5f);
const float sin_roll = sinf(roll_rad * 0.5f);
const float cos_roll = cosf(roll_rad * 0.5f);
float m[3][3][3];
float temp[3][3];
float m[3][4];
float tmp[2][4];
m[0][0][0] = cos_yaw; m[0][0][1] = 0; m[0][0][2] = sin_yaw;
m[0][1][0] = 0; m[0][1][1] = 1; m[0][1][2] = 0;
m[0][2][0] = -sin_yaw; m[0][2][1] = 0; m[0][2][2] = cos_yaw;
m[0][0] = cos_yaw; m[0][1] = 0.f; m[0][2] = sin_yaw; m[0][3] = 0.f;
m[1][0] = cos_pitch; m[1][1] = sin_pitch; m[1][2] = 0.f; m[1][3] = 0.f;
m[2][0] = cos_roll; m[2][1] = 0.f; m[2][2] = 0.f; m[2][3] = sin_roll;
m[1][0][0] = 1; m[1][0][1] = 0; m[1][0][2] = 0;
m[1][1][0] = 0; m[1][1][1] = cos_pitch; m[1][1][2] = -sin_pitch;
m[1][2][0] = 0; m[1][2][1] = sin_pitch; m[1][2][2] = cos_pitch;
multiply_quaternion(tmp[0], rot_quaternion[0], m[rotation_order[0]]);
multiply_quaternion(tmp[1], tmp[0], m[rotation_order[1]]);
multiply_quaternion(rot_quaternion[0], tmp[1], m[rotation_order[2]]);
m[2][0][0] = cos_roll; m[2][0][1] = -sin_roll; m[2][0][2] = 0;
m[2][1][0] = sin_roll; m[2][1][1] = cos_roll; m[2][1][2] = 0;
m[2][2][0] = 0; m[2][2][1] = 0; m[2][2][2] = 1;
multiply_matrix(temp, m[rotation_order[0]], m[rotation_order[1]]);
multiply_matrix(rot_mat, temp, m[rotation_order[2]]);
conjugate_quaternion(rot_quaternion[1], rot_quaternion[0]);
}
/**
* Rotate vector with given rotation matrix.
* Rotate vector with given rotation quaternion.
*
* @param rot_mat rotation matrix
* @param rot_quaternion rotation quaternion
* @param vec vector
*/
static inline void rotate(const float rot_mat[3][3],
static inline void rotate(const float rot_quaternion[2][4],
float *vec)
{
const float x_tmp = vec[0] * rot_mat[0][0] + vec[1] * rot_mat[0][1] + vec[2] * rot_mat[0][2];
const float y_tmp = vec[0] * rot_mat[1][0] + vec[1] * rot_mat[1][1] + vec[2] * rot_mat[1][2];
const float z_tmp = vec[0] * rot_mat[2][0] + vec[1] * rot_mat[2][1] + vec[2] * rot_mat[2][2];
float qv[4], temp[4], rqv[4];
vec[0] = x_tmp;
vec[1] = y_tmp;
vec[2] = z_tmp;
qv[0] = 0;
qv[1] = vec[0];
qv[2] = vec[1];
qv[3] = vec[2];
multiply_quaternion(temp, rot_quaternion[0], qv);
multiply_quaternion(rqv, temp, rot_quaternion[1]);
vec[0] = rqv[1];
vec[1] = rqv[2];
vec[2] = rqv[3];
}
static inline void set_mirror_modifier(int h_flip, int v_flip, int d_flip,
@ -4109,7 +4112,7 @@ static av_always_inline int v360_slice(AVFilterContext *ctx, void *arg, int jobn
else
out_mask = s->out_transform(s, i, j, width, height, vec);
av_assert1(!isnan(vec[0]) && !isnan(vec[1]) && !isnan(vec[2]));
rotate(s->rot_mat, vec);
rotate(s->rot_quaternion, vec);
av_assert1(!isnan(vec[0]) && !isnan(vec[1]) && !isnan(vec[2]));
normalize_vector(vec);
mirror(s->output_mirror_modifier, vec);
@ -4667,7 +4670,14 @@ static int config_output(AVFilterLink *outlink)
return err;
}
calculate_rotation_matrix(s->yaw, s->pitch, s->roll, s->rot_mat, s->rotation_order);
s->rot_quaternion[0][0] = 1.f;
s->rot_quaternion[0][1] = s->rot_quaternion[0][2] = s->rot_quaternion[0][3] = 0.f;
for (int i = 0; i < 4; i++) {
calculate_rotation(s->yaw * 0.25f, s->pitch * 0.25f, s->roll * 0.25f,
s->rot_quaternion, s->rotation_order);
}
set_mirror_modifier(s->h_flip, s->v_flip, s->d_flip, s->output_mirror_modifier);
ctx->internal->execute(ctx, v360_slice, NULL, NULL, s->nb_threads);