XMXDEC4::XMXDEC4(constfloat*) function (directxpackedvector.h)

Article
02/22/2024

Initializes a new instance of XMXDEC4 from a four element float array argument.

This constructor initializes a new instance of XMXDEC4 from a four element float array argument.

Note This constructor is only available under C++.

Syntax

void XMXDEC4(
  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 XMXDEC4.

Return value

None

Remarks

As XMXDEC4 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 XMXDEC4 as follows:

XMXDEC4 Member	Array Element	Range
x	pArray[0]	-511, 511
y	pArray[1]	-511, 511
z	pArray[2]	-511, 511
w	pArray[3]	0, 3

Elements of pArray will be clamped to the permitted range prior to assignment to the appropriate member of XMXDEC4.

The following pseudocode demonstrates the operation of this constructor, which takes advantage of the union of the four components of the XMXDEC4 vector with an instance of uint32_t in the definition of the structure:

XMXDEC4 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], 0.0 ), 3.0 );

instance.v =  ( (int32_t)_w1 << 30) |
              (((int32_t)_z1 & 0x3FF) << 20) |
              (((int32_t)_y1 & 0x3FF) << 10) |
              (((uint32_t)_x1 & 0x3FF));

Requirements

Requirement	Value
Target Platform	Windows
Header	directxpackedvector.h