Commit: 5770d691bbed31d05ecf22383f56df2a4371acfa
Author: Campbell Barton
Date: Thu Apr 3 21:47:03 2014 +1100
https://developer.blender.org/rB5770d691bbed31d05ecf22383f56df2a4371acfa
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
===================================================================
M source/blender/blenlib/BLI_math_vector.h
M source/blender/blenlib/intern/convexhull2d.c
M source/blender/blenlib/intern/math_vector_inline.c
===================================================================
diff --git a/source/blender/blenlib/BLI_math_vector.h
b/source/blender/blenlib/BLI_math_vector.h
index 1f4ccf8..a9edfa0 100644
--- a/source/blender/blenlib/BLI_math_vector.h
+++ b/source/blender/blenlib/BLI_math_vector.h
@@ -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;
diff --git a/source/blender/blenlib/intern/convexhull2d.c
b/source/blender/blenlib/intern/convexhull2d.c
index 2c29ef0..9f50963 100644
--- a/source/blender/blenlib/intern/convexhull2d.c
+++ b/source/blender/blenlib/intern/convexhull2d.c
@@ -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;
}
/**
diff --git a/source/blender/blenlib/intern/math_vector_inline.c
b/source/blender/blenlib/intern/math_vector_inline.c
index 59d5f7e..aed604e 100644
--- a/source/blender/blenlib/intern/math_vector_inline.c
+++ b/source/blender/blenlib/intern/math_vector_inline.c
@@ -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])
{
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