From c4df992fc107fc5938dd81dadcd37eefd87fbe38 Mon Sep 17 00:00:00 2001
From: Erich Gubler <erichdongubler@gmail.com>
Date: Thu, 18 Jan 2024 17:10:08 -0500
Subject: [PATCH] feat(const_eval): impl. `trunc`

---
 CHANGELOG.md                        | 1 +
 naga/src/proc/constant_evaluator.rs | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e3dd7bd1bdd..34d7912a82c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -77,6 +77,7 @@ Bottom level categories:
         - `radians`
         - `reverseBits`
         - `sign`
+        - `trunc`
 
 ## v0.19.0 (2024-01-17)
 
diff --git a/naga/src/proc/constant_evaluator.rs b/naga/src/proc/constant_evaluator.rs
index ad390e45428..497ef15c475 100644
--- a/naga/src/proc/constant_evaluator.rs
+++ b/naga/src/proc/constant_evaluator.rs
@@ -1010,6 +1010,9 @@ impl<'a> ConstantEvaluator<'a> {
                     Ok([if edge <= x { 1.0 } else { 0.0 }])
                 })
             }
+            crate::MathFunction::Trunc => {
+                component_wise_float!(self, span, [arg], |e| { Ok([e.trunc()]) })
+            }
             fun => Err(ConstantEvaluatorError::NotImplemented(format!(
                 "{fun:?} built-in function"
             ))),