expp - vs
Microsoft DirectX 9.0 SDK Update (October 2004)

expp - vs


Provides partial precision exponential 2x.

Syntax

expp dst, src.{x|y|z|w}

Where:

Remarks

Vertex shader versions1_12_02_x2_sw3_03_sw
exppxxxxxx

vs_1_1

The expp - vs instruction operates differently depending on vertex shader versions.

In vs_1_1, the expp instruction gives the following results:

v = the scalar value from the source register with a replicate swizzle

dest.x = pow(2, floor(v))
dest.y = v - floor(v)
dest.z = pow(2, v) (partial-precision)
dest.w = 1

In vs_2_0 and up, the expp instruction gives the following results:

v = the scalar value from the source register with a replicate swizzle

dest.x = dest.y = dest.z = dest.y = pow(2, v) (partial-precision)

vs_2_0

In vs_2_0 and up, the instruction works like this:

float V = the scalar value from the source register with a replicate swizzle

dest.x = dest.y = dest.z = dest.y = pow( 2, V ) (partial-precision)

The instruction provides at least 10 bits of precision.



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