std.not mimics WGSL

Author: cieplypolar

packages/typegpu/src/std/boolean.ts

@@ -180,6 +180,10 @@ function cpuNot(value: number): boolean;
 function cpuNot<T extends AnyVecInstance>(value: T): VecInstanceToBooleanVecInstance<T>;
 function cpuNot(value: unknown): boolean;
 function cpuNot(value: unknown): boolean | AnyBooleanVecInstance {
+  if (typeof value === 'number' && isNaN(value)) {
+    return false;
+  }
+
   if (isVecInstance(value)) {
     if (value.length === 2) {
       return vec2b(!value.x, !value.y);
@@ -206,6 +210,7 @@ function cpuNot(value: unknown): boolean | AnyBooleanVecInstance {
  * not(vec3b(true, true, false)) // returns vec3b(false, false, true)
  * not(vec3f(1.0, 0.0, -1.0)) // returns vec3b(false, true, false)
  * not({a: 1882}) // returns false
+ * not(NaN) // returns false **as in WGSL**
  */
 export const not = dualImpl({
   name: 'not',
@@ -217,8 +222,11 @@ export const not = dualImpl({
     };
   },
   normalImpl: cpuNot,
-  codegenImpl: (ctx, [arg]) => {
+  codegenImpl: (_ctx, [arg]) => {
     if (isKnownAtComptime(arg)) {
+      if (typeof arg.value === 'number' && isNaN(arg.value)) {
+        return 'false';
+      }
       return `${!arg.value}`;
     }
 

packages/typegpu/src/tgsl/wgslGenerator.ts

@@ -173,7 +173,8 @@ const unaryOpCodeToCodegen = {
       return snip(`!${argStr}`, bool, 'runtime');
     }
     if (wgsl.isNumericSchema(dataType)) {
-      return snip(`!bool(${argStr})`, bool, 'runtime');
+      // no bool cast, because bool(NaN) is true in WGSL but in JS it's false
+      return snip(`!(${argStr} != 0)`, bool, 'runtime');
     }
 
     return snip(false, bool, 'constant');

packages/typegpu/tests/std/boolean/not.test.ts

@@ -36,6 +36,10 @@ describe('not', () => {
     expect(not(s)).toBe(false);
   });
 
+  it('mimics WGSL behavior on NaN', () => {
+    expect(not(NaN)).toBe(false);
+  });
+
   it('generates correct WGSL on a boolean runtime-known argument', () => {
     const testFn = tgpu.fn(
       [d.bool],