feat(const_eval): impl. atan

Author: ErichDonGubler

CHANGELOG.md

@@ -92,6 +92,7 @@ Wgpu now exposes backend feature for the Direct3D 12 (`dx12`) and Metal (`metal`
         - `acosh`
         - `asin`
         - `asinh`
+        - `atan`
         - `cos`
         - `cosh`
         - `round`

naga/src/proc/constant_evaluator.rs

@@ -830,6 +830,9 @@ impl<'a> ConstantEvaluator<'a> {
             crate::MathFunction::Asinh => {
                 component_wise_float!(self, span, [arg], |e| { Ok([e.asinh()]) })
             }
+            crate::MathFunction::Atan => {
+                component_wise_float!(self, span, [arg], |e| { Ok([e.atan()]) })
+            }
             crate::MathFunction::Pow => self.math_pow(arg, arg1.unwrap(), span),
             crate::MathFunction::Clamp => {
                 component_wise_scalar!(