BLI_math 'compare' cleanup & enhancements.

This commit:
* Adds a 'compare_ff' function for absolute 'almost equal' comparison of floats.
* Makes 'compare_vxvx' functions use that new 'compare_ff' one.
* Adds a 'compare_ff_relative' function for secured ulp-based relative comparison of floats.
* Adds matching 'compare_vxvx_relative' functions.
* Adds some basic tests for compare_ff_relative.

See https://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/

Note that we could replace our python/mathutils' EXPP_FloatsAreEqual() by BLI's compare_ff_relative
(using a very small absolute max_diff), but these do not have exact same behavior...
Left a comment there for now, we can do it later if/when we are sure it won't break anything!

1 files changed, 34 insertions, 21 deletions

diff --git a/source/blender/blenlib/intern/math_vector_inline.c b/source/blender/blenlib/intern/math_vector_inline.c
index fb33fed33e4..c21b09748c9 100644
--- a/source/blender/blenlib/intern/math_vector_inline.c
+++ b/source/blender/blenlib/intern/math_vector_inline.c
@@ -966,23 +966,47 @@ MINLINE bool equals_v4v4(const float v1[4], const float v2[4])
 
 MINLINE bool compare_v2v2(const float v1[2], const float v2[2], const float limit)
 {
-	if (fabsf(v1[0] - v2[0]) <= limit)
-		if (fabsf(v1[1] - v2[1]) <= limit)
-			return true;
-
-	return false;
+	return (compare_ff(v1[0], v2[0], limit) &&
+	        compare_ff(v1[1], v2[1], limit));
 }
 
 MINLINE bool compare_v3v3(const float v1[3], const float v2[3], const float limit)
 {
-	if (fabsf(v1[0] - v2[0]) <= limit)
-		if (fabsf(v1[1] - v2[1]) <= limit)
-			if (fabsf(v1[2] - v2[2]) <= limit)
-				return true;
+	return (compare_ff(v1[0], v2[0], limit) &&
+	        compare_ff(v1[1], v2[1], limit) &&
+	        compare_ff(v1[2], v2[2], limit));
+}
+
+MINLINE bool compare_v4v4(const float v1[4], const float v2[4], const float limit)
+{
+	return (compare_ff(v1[0], v2[0], limit) &&
+	        compare_ff(v1[1], v2[1], limit) &&
+	        compare_ff(v1[2], v2[2], limit) &&
+	        compare_ff(v1[3], v2[3], limit));
+}
 
-	return false;
+MINLINE bool compare_v2v2_relative(const float v1[2], const float v2[2], const float limit, const int max_ulps)
+{
+	return (compare_ff_relative(v1[0], v2[0], limit, max_ulps) &&
+	        compare_ff_relative(v1[1], v2[1], limit, max_ulps));
+}
+
+MINLINE bool compare_v3v3_relative(const float v1[3], const float v2[3], const float limit, const int max_ulps)
+{
+	return (compare_ff_relative(v1[0], v2[0], limit, max_ulps) &&
+	        compare_ff_relative(v1[1], v2[1], limit, max_ulps) &&
+	        compare_ff_relative(v1[2], v2[2], limit, max_ulps));
 }
 
+MINLINE bool compare_v4v4_relative(const float v1[4], const float v2[4], const float limit, const int max_ulps)
+{
+	return (compare_ff_relative(v1[0], v2[0], limit, max_ulps) &&
+	        compare_ff_relative(v1[1], v2[1], limit, max_ulps) &&
+	        compare_ff_relative(v1[2], v2[2], limit, max_ulps) &&
+	        compare_ff_relative(v1[3], v2[3], limit, max_ulps));
+}
+
+
 MINLINE bool compare_len_v3v3(const float v1[3], const float v2[3], const float limit)
 {
 	float x, y, z;
@@ -1005,17 +1029,6 @@ MINLINE bool compare_len_squared_v3v3(const float v1[3], const float v2[3], cons
 	return ((x * x + y * y + z * z) <= limit_sq);
 }
 
-MINLINE bool compare_v4v4(const float v1[4], const float v2[4], const float limit)
-{
-	if (fabsf(v1[0] - v2[0]) <= limit)
-		if (fabsf(v1[1] - v2[1]) <= limit)
-			if (fabsf(v1[2] - v2[2]) <= limit)
-				if (fabsf(v1[3] - v2[3]) <= limit)
-					return true;
-
-	return false;
-}
-
 /**
  * <pre>
  *        + l1