Merge pull request #3 from 5150VEX/unit-coercion

Add unit_cast, to_linear, and to_angular functions
LemLib · May 31, 2024 · a34ae66 · a34ae66
2 parents 3416834 + c879979
commit a34ae66
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Showing 2 changed files with 30 additions and 1 deletion.
diff --git a/include/units/units.hpp b/include/units/units.hpp
@@ -110,6 +110,9 @@ template <TYPENAMES> void quantityChecker(Quantity<DIMS> q) {}
 template <typename Q>
 concept isQuantity = requires(Q q) { quantityChecker(q); };
 
+// Un(type)safely coerce the a unit into a different unit
+template <isQuantity Q1, isQuantity Q2> constexpr inline Q1 unit_cast(Q2 quantity) { return Q1(quantity.val()); }
+
 template <isQuantity Q1, isQuantity Q2> using QMultiplication = Quantity<
     std::ratio_add<typename Q1::mass, typename Q2::mass>, std::ratio_add<typename Q1::length, typename Q2::length>,
     std::ratio_add<typename Q1::time, typename Q2::time>, std::ratio_add<typename Q1::current, typename Q2::current>,
@@ -308,4 +311,26 @@ template <isQuantity Q> constexpr Q trunc(const Q& lhs, const Q& rhs) {
 template <isQuantity Q> constexpr Q round(const Q& lhs, const Q& rhs) {
     return Q(std::round(lhs.val() / rhs.val()) * rhs.val());
 }
-} // namespace units
+} // namespace units
+
+// Convert an angular unit `Q` to a linear unit correctly;
+// mostly useful for velocities
+template <isQuantity Q>
+Quantity<typename Q::mass, typename Q::angle, typename Q::time, typename Q::current, typename Q::length> toLinear(
+    Quantity<typename Q::mass, typename Q::length, typename Q::time, typename Q::current, typename Q::angle> angular,
+    Length diameter) {
+    return unit_cast<
+        Quantity<typename Q::mass, typename Q::angle, typename Q::time, typename Q::current, typename Q::length>>(
+        angular * (diameter / 2.0));
+}
+
+// Convert an linear unit `Q` to a angular unit correctly;
+// mostly useful for velocities
+template <isQuantity Q>
+Quantity<typename Q::mass, typename Q::angle, typename Q::time, typename Q::current, typename Q::length> toAngular(
+    Quantity<typename Q::mass, typename Q::length, typename Q::time, typename Q::current, typename Q::angle> linear,
+    Length diameter) {
+    return unit_cast<
+        Quantity<typename Q::mass, typename Q::angle, typename Q::time, typename Q::current, typename Q::length>>(
+        linear / (diameter / 2.0));
+}
diff --git a/src/main.cpp b/src/main.cpp
@@ -33,6 +33,10 @@ void initialize() {
     num = 0.0;
     a.theta().convert(deg);
     to_cDeg(a.theta());
+
+    Length x = unit_cast<Length>(num);
+    Angle y = toAngular<Length>(x, 2_cm);
+    Length z = toLinear<Angle>(y, 2_cm);
 }
 
 /**