stride3d/stride · error · NotImplementedException

Variable initializer is not supported on streams variable

Error message

Variable initializer is not supported on streams variable

What it means

StreamAnalyzer.Analyze collects stream (interface) variables. A stream variable with an initializer would imply the interface variable has a default value, which SPIR-V interface variables don't support, so a VariableFlagsMask.Stream variable with MethodOrConstantInitializer set throws NotImplementedException.

Solutions

1. Remove the initializer from the stream/interface variable declaration
2. Initialize the value inside the stage function body instead (e.g. assign at the start of the shader)
3. Ensure no compiler transformation attaches initializers to stream-flagged variables

Example fix

// before (SDSL)
stage float3 Normal = float3(0, 1, 0);
// after
stage float3 Normal; // assign inside the stage body instead

if (variable.Flags.HasFlag(VariableFlagsMask.Stream) && variable.MethodOrConstantInitializer != null)
    throw new NotSupportedException($"Stream variable {variable.ResultId} must not have an initializer");

bool IsPlainStreamVariable(VariableInfo v) => v.Flags.HasFlag(VariableFlagsMask.Stream) && v.MethodOrConstantInitializer is null;

try { analyzer.Analyze(module); } catch (NotImplementedException ex) { logger.LogError(ex, "Stream variable with initializer"); throw; }

When it happens

Trigger: Declaring a `streams` input/output variable with an initializer (e.g. `float3 Normal = float3(0,1,0);` on a stream variable) so the SPIR-V OpVariable carries an Initializer operand while flagged Stream.

Common situations: SDSL shader giving a default value to an in/out interface variable; a transformation copying a constant initializer onto a stream variable.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Can't write value on input or output struct
• OpAccessChain on PatchType/array-of-Streams can have only 1…
• 64bit integers
• Can't add type
• Could not load shader

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/f366457735f14e98. Report an issue: GitHub.

Appendix: source

Thrown at sources/shaders/Stride.Shaders.Parsers/Spirv/Processing/Interfaces/Analysis/StreamAnalyzer.cs:105

            if (i.Op == Op.OpVariableSDSL && ((OpVariableSDSL)i) is
                {
                    StorageClass: StorageClass.Private or StorageClass.Workgroup or StorageClass.Uniform,
                    ResultId: int
                } variable
                && context.ReverseTypes[variable.ResultType] is PointerType { BaseType: not ConstantBufferSymbol })
            {
                var name = nameTable.TryGetValue(variable.ResultId, out var nameId)
                    ? nameId
                    : $"unnamed_{variable.ResultId}";
                var type = (PointerType)context.ReverseTypes[variable.ResultType];

                if (variable.Flags.HasFlag(VariableFlagsMask.Stream))
                {
                    semanticTable.TryGetValue(variable.ResultId, out var semantic);

                    if (variable.MethodOrConstantInitializer != null)
                        throw new NotImplementedException("Variable initializer is not supported on streams variable");

                    streams.Add(variable.ResultId, new StreamVariableInfo(semantic, name, type, variable.ResultId) { Patch = patchVariables.Contains(variable.ResultId) });
                }
                else
                {
                    variables.Add(variable.ResultId, new VariableInfo(name, type, variable.ResultId)
                    {
                        VariableMethodInitializerId = variable.MethodOrConstantInitializer,
                    });
                }
            }

            if (i.Op == Op.OpVariableSDSL && ((OpVariableSDSL)i) is
                {
                    StorageClass: StorageClass.UniformConstant or StorageClass.StorageBuffer,
                    ResultId: int
                } resource)
            {

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