dp2add (Pixel Shader)

Performs a 2-D dot product and a scalar addition.

Syntax

dp2add[_sat] dst[.mask], [-]src0[.swizzle], 
                         [-]src1[.swizzle],
                         [-]src2[.replicate_swizzle]

Where:

• [_sat] - is an optional saturate modifier.
• dest - is a destination register. The see more about the limitations of pixel shader registers with this instruction, see the remarks below.
• [_mask] - is an optional mask modifier.
• [-] - is an optional negate modifier.
• src0, src1, src2 - three input source registers. Each of these registers allows an optional negate [-] modifier. src0 and src1 allow an optional swizzle mask [.swizzle]. src2 requires replicate swizzle mask. [.replicate_swizzle].
• [swizzle, replicateSwizzle-] - are optional swizzle modifiers.

Remarks

The scalar value for add is chosen by the replicate swizzle on src2.

The following code fragment shows the operations performed.

dest = src0.r * src1.r + src0.g * src1.g + src2.selected_component
// The scalar result is replicated to write mask components

Instruction Information