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Optimize BLI_convexhull_aabb_fit_hull_2d, avoid atan2, sin, cos 

add utility functions for using a 2d unit vector as a rotation matrix
mul_v2_v2_cw & mul_v2_v2_ccw
This commit is contained in:
Campbell Barton 2014-04-03 21:47:03 +11:00
parent 51abc2becd
commit 5770d691bb
3 changed files with 33 additions and 10 deletions
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2
source/blender/blenlib/BLI_math_vector.h
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@ -117,6 +117,8 @@ MINLINE void mul_v3_v3(float r[3], const float a[3]);
MINLINE void mul_v3_v3v3(float r[3], const float a[3], const float b[3]);
MINLINE void mul_v4_fl(float r[4], float f);
MINLINE void mul_v4_v4fl(float r[3], const float a[3], float f);
MINLINE void mul_v2_v2_cw(float r[2], const float mat[2], const float vec[2]);
MINLINE void mul_v2_v2_ccw(float r[2], const float mat[2], const float vec[2]);
MINLINE float mul_project_m4_v3_zfac(float mat[4][4], const float co[3]) ATTR_WARN_UNUSED_RESULT;
MINLINE float dot_m3_v3_row_x(float M[3][3], const float a[3]) ATTR_WARN_UNUSED_RESULT;
MINLINE float dot_m3_v3_row_y(float M[3][3], const float a[3]) ATTR_WARN_UNUSED_RESULT;

16
source/blender/blenlib/intern/convexhull2d.c
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@ -253,28 +253,24 @@ float BLI_convexhull_aabb_fit_hull_2d(const float (*points_hull)[2], unsigned in
{
unsigned int i, i_prev;
float area_best = FLT_MAX;
float angle_best = 0.0f;
float dvec_best[2]; /* best angle, delay atan2 */
i_prev = n - 1;
for (i = 0; i < n; i++) {
const float *ev_a = points_hull[i];
const float *ev_b = points_hull[i_prev];
float dvec[2];
float dvec[2]; /* 2d rotation matrix */
sub_v2_v2v2(dvec, ev_a, ev_b);
if (normalize_v2(dvec) != 0.0f) {
float mat[2][2];
/* rotation matrix */
float min[2] = {FLT_MAX, FLT_MAX}, max[2] = {-FLT_MAX, -FLT_MAX};
unsigned int j;
const float angle = atan2f(dvec[0], dvec[1]);
float area;
angle_to_mat2(mat, angle);
for (j = 0; j < n; j++) {
float tvec[2];
mul_v2_m2v2(tvec, mat, points_hull[j]);
mul_v2_v2_cw(tvec, dvec, points_hull[j]);
min[0] = min_ff(min[0], tvec[0]);
min[1] = min_ff(min[1], tvec[1]);
@ -290,14 +286,14 @@ float BLI_convexhull_aabb_fit_hull_2d(const float (*points_hull)[2], unsigned in
if (area < area_best) {
area_best = area;
angle_best = angle;
copy_v2_v2(dvec_best, dvec);
}
}
i_prev = i;
}
return angle_best;
return (area_best != FLT_MAX) ? atan2f(dvec_best[0], dvec_best[1]) : 0.0f;
}
/**

25
source/blender/blenlib/intern/math_vector_inline.c
View File

@ -432,6 +432,31 @@ MINLINE void mul_v4_v4fl(float r[4], const float a[4], float f)
r[3] = a[3] * f;
}
/**
* Avoid doing:
*
* angle = atan2f(dvec[0], dvec[1]);
* angle_to_mat2(mat, angle);
*
* instead use a vector as a matrix.
*/
MINLINE void mul_v2_v2_cw(float r[2], const float mat[2], const float vec[2])
{
BLI_assert(r != vec);
r[0] = mat[0] * vec[0] + (+mat[1]) * vec[1];
r[1] = mat[1] * vec[0] + (-mat[0]) * vec[1];
}
MINLINE void mul_v2_v2_ccw(float r[2], const float mat[2], const float vec[2])
{
BLI_assert(r != vec);
r[0] = mat[0] * vec[0] + (-mat[1]) * vec[1];
r[1] = mat[1] * vec[0] + (+mat[0]) * vec[1];
}
/* note: could add a matrix inline */
MINLINE float mul_project_m4_v3_zfac(float mat[4][4], const float co[3])
{