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Appendix B Language Profiles
To specify bindings between texture units and uniform parameters/texture coordinates to match their application, all sampler uniform parameters and texture coordinate inputs that are used in the program must have matching binding semantics—that is, TEXUNIT<n> may only be used with TEXCOORD<n>.
Partially specified binding semantics may not work in all cases. Fundamentally, this restriction is due to the close coupling between texture samplers and texture coordinates in DirectX pixel shaders 1_X.
Binding Semantics for Uniform Data
If a binding semantic for a uniform parameter is not specified then the compiler will allocate one automatically. Scalar uniform parameters may be allocated to either the xyz or the w portion of a constant register depending on how they are used within the Cg program. When using the output of the compiler without the Cg runtime, you must set all values of a scalar uniform to the desired scalar value, not just the x component. The valid binding semantics for uniform parameters in the ps_1_X profiles are summarized in Table 51.
Table 51. ps_1_x Uniform Input Binding Semantics
Binding Semantics Name
Corresponding Data
register(s0)—register(s3)
TEXUNIT0—TEXTUNIT3
Texture unit N, where N is in range [0..3].
May be used only with uniform inputs with
sampler* types.
register(c0)–register(c7)
C0–C7
Constant register [0..7]
Binding Semantics for Varying Input/Output Data
The varying input binding semantics in the ps_1_X profiles are the same as the varying output binding semantics of the vs_1_1 profile.
Varying input binding semantics in the ps_1_X profiles consist of COLOR0, COLOR1, TEXCOORD0, TEXCOORD1, TEXCOORD2 and TEXCOORD3. These map to output registers in DirectX vertex shaders. 808-00504-0000-006
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