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Source register swizzling (HLSL PS reference)

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Swizzling refers to the ability to copy any source register component to any temporary register component. Swizzling does not affect the source register data. Before an instruction runs, the data in a source register is copied to a temporary register.

Source Swizzling

Source swizzle allows individual component of a source register to take on the value of any of the four components of the same source register before the register is read for computation.

For example, the .zxxy swizzle means:

  • .x component will take on the value of .z component
  • .y component will take on the value of .x component
  • .z component will take on the value of .x component
  • .w component will take on the value of .y component

The components can appear in any order. If fewer than four components are specified, the last component is repeated. For example:

.xy  = .xyyy
.wzx = .wzxx
.z   = .zzzz

If no component is specified, no swizzling is applied.

Some instructions have restrictions for source swizzle. They are listed in the respected instruction reference pages.

Pixel shader versions 1_1 1_2 1_3 1_4 2_0 2_x 2_sw 3_0 3_sw
.x x x x x x x
.y x x x x x x
.z x* x* x* x x x x x x
.w x x x x x x x x x
.xyzw (default) x x x x x x x x x
.yzxw x x x x x
.zxyw x x x x x
.wzyx x x x x x
arbitrary swizzle x x x x

 

* Only available if destination write mask is .w (.a).

Arbitrary Swizzle

Swizzles can be applied to source registers in an arbitrary order; that is, any source register can take any component mask, in any order.

Replicate Swizzle

Replicate swizzle copies one component to another. This is, exactly one of the .x, .y, .z, .w swizzle components (or the .r, .g, .b, .a equivalents) must be specified.

Pixel Shader Source Register Modifiers

ps_1_1__ps_1_2__ps_1_3__ps_1_4 Registers

ps_2_0 Registers

ps_2_x Registers

ps_3_0 Registers