add remap_default (issue 1157)

core/variant/variant_utility.cpp

@@ -556,6 +556,13 @@ double VariantUtilityFunctions::remap(double value, double istart, double istop,
 	return Math::remap(value, istart, istop, ostart, ostop);
 }
 
+double VariantUtilityFunctions::remap_default(double value, double istart, double istop, double ostart, double ostop, double default_value) {
+	if (istart == istop) {
+		return default_value;
+	}
+	return Math::remap(value, istart, istop, ostart, ostop);
+}
+
 double VariantUtilityFunctions::smoothstep(double from, double to, double val) {
 	return Math::smoothstep(from, to, val);
 }
@@ -1745,6 +1752,7 @@ void Variant::_register_variant_utility_functions() {
 	FUNCBINDR(lerp_angle, sarray("from", "to", "weight"), Variant::UTILITY_FUNC_TYPE_MATH);
 	FUNCBINDR(inverse_lerp, sarray("from", "to", "weight"), Variant::UTILITY_FUNC_TYPE_MATH);
 	FUNCBINDR(remap, sarray("value", "istart", "istop", "ostart", "ostop"), Variant::UTILITY_FUNC_TYPE_MATH);
+	FUNCBINDR(remap_default, sarray("value", "istart", "istop", "ostart", "ostop", "default_value"), Variant::UTILITY_FUNC_TYPE_MATH);
 
 	FUNCBINDR(smoothstep, sarray("from", "to", "x"), Variant::UTILITY_FUNC_TYPE_MATH);
 	FUNCBINDR(move_toward, sarray("from", "to", "delta"), Variant::UTILITY_FUNC_TYPE_MATH);

core/variant/variant_utility.h

@@ -95,6 +95,7 @@ struct VariantUtilityFunctions {
 	static double lerp_angle(double from, double to, double weight);
 	static double inverse_lerp(double from, double to, double weight);
 	static double remap(double value, double istart, double istop, double ostart, double ostop);
+	static double remap_default(double value, double istart, double istop, double ostart, double ostop, double default_value);
 	static double smoothstep(double from, double to, double val);
 	static double move_toward(double from, double to, double delta);
 	static double rotate_toward(double from, double to, double delta);

doc/classes/@GlobalScope.xml

@@ -1102,7 +1102,24 @@
 				remap(75, 0, 100, -1, 1) # Returns 0.5
 				[/codeblock]
 				For complex use cases where multiple ranges are needed, consider using [Curve] or [Gradient] instead.
-				[b]Note:[/b] If [code]istart == istop[/code], the return value is undefined (most likely NaN, INF, or -INF).
+				[b]Note:[/b] If [code]istart == istop[/code], the return value is undefined (most likely NaN, INF, or -INF). See also [method remap_default].
+			</description>
+		</method>
+		<method name="remap_default" keywords="range, lerp, interpolate">
+			<return type="float" />
+			<param index="0" name="value" type="float" />
+			<param index="1" name="istart" type="float" />
+			<param index="2" name="istop" type="float" />
+			<param index="3" name="ostart" type="float" />
+			<param index="4" name="ostop" type="float" />
+			<param index="5" name="default_value" type="float" />
+			<description>
+				Maps a [param value] from range [code][istart, istop][/code] to [code][ostart, ostop][/code] and returns [param default_value] if [code]istart == istop[/code]. See also [method remap], [method lerp] and [method inverse_lerp]. If [param value] is outside [code][istart, istop][/code], then the resulting value will also be outside [code][ostart, ostop][/code]. If this is not desired, use [method clamp] on the result of this function.
+				[codeblock]
+				remap_default(75, 0, 100, -1, 1, 3) # Returns 0.5
+				remap_default(75, 0, 0, -1, 1, 3) # Returns 3.0
+				[/codeblock]
+				For complex use cases where multiple ranges are needed, consider using [Curve] or [Gradient] instead.
 			</description>
 		</method>
 		<method name="rid_allocate_id">