reinforced animation accessors validation

Author: vpenades

src/SharpGLTF.Core/Schema2/gltf.Accessors.cs

@@ -576,14 +576,14 @@ internal void ValidateMatrices4x3(VALIDATIONCTX validate, bool mustInvert = true
 
         internal void ValidateAnimationInput(VALIDATIONCTX validate)
         {
-            SourceBufferView.ValidateBufferUsagePlainData(validate);
+            SourceBufferView.ValidateBufferUsagePlainData(validate, false); // as per glTF specification, animation accessors must not have ByteStride
 
             validate.IsAnyOf(nameof(Dimensions), Dimensions, DimensionType.SCALAR);
         }
 
         internal void ValidateAnimationOutput(VALIDATIONCTX validate)
         {
-            SourceBufferView.ValidateBufferUsagePlainData(validate);
+            SourceBufferView.ValidateBufferUsagePlainData(validate, false); // as per glTF specification, animation accessors must not have ByteStride
 
             validate.IsAnyOf(nameof(Dimensions), Dimensions, DimensionType.SCALAR, DimensionType.VEC3, DimensionType.VEC4);
         }

src/SharpGLTF.Core/Schema2/gltf.BufferView.cs

@@ -245,16 +245,17 @@ internal void ValidateBufferUsageGPU(Validation.ValidationContext validate, Buff
             if (this._target.HasValue) validate.EnumsAreEqual(nameof(_target), _target.Value, usingMode);
         }
 
-        internal void ValidateBufferUsagePlainData(Validation.ValidationContext validate)
-        {
-            /*
-            if (this._byteStride.HasValue)
+        internal void ValidateBufferUsagePlainData(Validation.ValidationContext validate, bool supportsStride = true)
+        {            
+            if (this._byteStride.HasValue && !supportsStride)
             {
-                if (result.TryFixLinkOrError("BufferView", "Unexpected ByteStride found. Expected null"))
+                if (validate.TryFix)
                 {
                     this._byteStride = null;
                 }
-            }*/
+
+                validate.IsUndefined(nameof(_byteStride), this._byteStride);                
+            }
 
             validate = validate.GetContext(this);