XMDEC4::XMDEC4(constfloat*) function (directxpackedvector.h)

Article
02/22/2024

Initializes a new instance of XMDEC4 from a four element float array argument.

This constructor initializes a new instance of XMDEC4 from a from a four element float array argument.

Note This constructor is only available under C++.

Syntax

void XMDEC4(
  const float *pArray
) noexcept;

Parameters

pArray

Four element floating point array containing the values used to initialize the four components of a new instance of XMDEC4.

Return value

None

Remarks

As XMDEC4 represents a four component integer vector, the fractional part of an element of pArray will be truncated.

Array elements are mapped to the vector components of a new instance of XMDEC4 as follows:

Vector Component	Array Element	Range
x	pArray[0]	-511, 511
y	pArray[1]	-511, 511
z	pArray[2]	-511, 511
w	pArray[3]	-1, 1

Elements of pArray will be clamped to the permitted range prior to assignment to the appropriate member of XMDEC4.

The following pseudocode demonstrates the operation of this constructor, which takes advantage of the union of the four components of the XMDEC4 vector with an instance of uint32_t in the definition of the structure:

XMDEC4 instance;
_x1=min( max( pArray[0], -511.0 ), 511.0 );
_y1=min( max( pArray[1], -511.0 ), 511.0 );
_z1=min( max( pArray[2], -511.0 ), 511.0 );
_w1=min( max( pArray[3], -1.0 ), 1.0 );

instance.v =  ( (int32_t)_w1 << 30) |
              (((int32_t)_z1 & 0x3FF) << 20) |
              (((int32_t)_y1 & 0x3FF) << 10) |
              (((int32_t)_x1 & 0x3FF));

Requirements

Requirement	Value
Target Platform	Windows
Header	directxpackedvector.h