diff options
Diffstat (limited to 'intern/cycles/util/util_math.h')
| -rw-r--r-- | intern/cycles/util/util_math.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/intern/cycles/util/util_math.h b/intern/cycles/util/util_math.h index 737c834e073..8caabf6eac3 100644 --- a/intern/cycles/util/util_math.h +++ b/intern/cycles/util/util_math.h @@ -787,6 +787,16 @@ ccl_device_inline float compare_floats(float a, float b, float abs_diff, int ulp return (abs(__float_as_int(a) - __float_as_int(b)) < ulp_diff); } +/* Calculate the angle between the two vectors a and b. + * The usual approach acos(dot(a, b)) has severe precision issues for small angles, + * which are avoided by this method. + * Based on "Mangled Angles" from https://people.eecs.berkeley.edu/~wkahan/Mindless.pdf + */ +ccl_device_inline float precise_angle(float3 a, float3 b) +{ + return 2.0f * atan2f(len(a - b), len(a + b)); +} + CCL_NAMESPACE_END #endif /* __UTIL_MATH_H__ */ |