Vertex Attributes

Pipeline vertex inputs are declared in an attributes block:

attributes {
    position: float3
    normal: float3
    texcoord: float2
}

Rules

• the first declared attribute must be position
• attributes are declared at pipeline scope
• graphics passes opt into them with use attributes { ... }
• shader code reads them through attributes.<name>

Selecting Attributes Per Pass

pass "Main" {
    use attributes { position, normal, texcoord }

    vertex {
        output.position = float4(attributes.position, 1.0);
        output.normal = attributes.normal;
        output.uv = attributes.texcoord;
    }
}

This allows different passes in the same pipeline to consume different subsets of the pipeline's attribute set.

Decorators

The current parser supports these decorators on attribute declarations:

• @compressed(...)
• @instance

Example:

attributes {
    position: float3 @compressed(10_10_10)
    normal: float3 @compressed(octahedral16)
    texcoord: float2 @compressed(unorm16_16)
    instanceColor: float4 @instance
}

Optional Attribute Use

The pass grammar also accepts an optional marker in use attributes:

use attributes { position, normal? }

This syntax introduces an implicit shader-variant fact named has_<attribute>. In the example above, the pipeline can branch on variants.has_normal and engine integrations can specialize the same pass for meshes that do or do not provide normal.

See Shader Variants for the full specialization model.

Access in Shader Code

vertex {
    float3 pos = attributes.position;
    float3 n = attributes.normal;
    float2 uv = attributes.texcoord;

    output.position = float4(pos, 1.0);
    output.normal = n;
    output.uv = uv;
}

Related

• Shader I/O
• The Pass
• The Pipeline