This PR handles the smoothstep degenerate case where the range is empty.

It also updates the documentation to describe positive and negative ranges.

Co-Authored-By: Hugo Locurcio <hugo.locurcio@hugo.pro>
Co-Authored-By: kleonc <9283098+kleonc@users.noreply.github.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/core/math/math_funcs.h b/core/math/math_funcs.h
index 3060f31970..fd53ed28fd 100644
--- a/core/math/math_funcs.h
+++ b/core/math/math_funcs.h
@@ -447,14 +447,22 @@ public:
 
 	static _ALWAYS_INLINE_ double smoothstep(double p_from, double p_to, double p_s) {
 		if (is_equal_approx(p_from, p_to)) {
-			return p_from;
+			if (likely(p_from <= p_to)) {
+				return p_s <= p_from ? 0.0 : 1.0;
+			} else {
+				return p_s <= p_to ? 1.0 : 0.0;
+			}
 		}
 		double s = CLAMP((p_s - p_from) / (p_to - p_from), 0.0, 1.0);
 		return s * s * (3.0 - 2.0 * s);
 	}
 	static _ALWAYS_INLINE_ float smoothstep(float p_from, float p_to, float p_s) {
 		if (is_equal_approx(p_from, p_to)) {
-			return p_from;
+			if (likely(p_from <= p_to)) {
+				return p_s <= p_from ? 0.0f : 1.0f;
+			} else {
+				return p_s <= p_to ? 1.0f : 0.0f;
+			}
 		}
 		float s = CLAMP((p_s - p_from) / (p_to - p_from), 0.0f, 1.0f);
 		return s * s * (3.0f - 2.0f * s);