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

Article
02/22/2024

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

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

Note This is only available for C++ based development.

Syntax

void XMCOLOR(
  const float *pArray
) noexcept;

Parameters

pArray

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

Return value

None

Remarks

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

Vector Component	Array Element	Range	Description
a	pArray[0]	0.0, 1.0	During instantiation, pArray[0] is clamped between 0 and 1, multiplied by 255.0f and assigned to a (alpha channel).
r	pArray[1]	0.0, 1.0	During instantiation, pArray[1] is clamped between 0 and 1, multiplied by 255.0f, and then assigned to r (red channel).
z	pArray[2]	0.0, 1.0	During instantiation, pArray[2] is clamped between 0 and 1, multiplied by 255.0f, and then assigned to g (green channel).
w	pArray[3]	0.0, 1.0	During instantiation, pArray[3] is clamped between 0 and 1, multiplied by 255.0f, and then assigned to b (blue channel).

The following pseudocode demonstrates the operation of this constructor, which takes advantage of the union of the four color channels of the XMCOLOR structure with an instance of uint32_t in the definition of the structure:

XMCOLOR instance;
_a1 = min( max( pArray[0], 0.0 ), 1.0 );
_r1 = min( max( pArray[1], 0.0 ), 1.0 );
_g1 = min( max( pArray[2], 0.0 ), 1.0 );
_b1 = min( max( pArray[3], 0.0 ), 1.0 );

_a1 = round ( _a1 * 255.0f );
_r1 = round ( _r1 * 255.0f );
_g1 = round ( _g1 * 255.0f );
_b1 = round ( _b1 * 255.0f );

instance.v =  ( (uint32_t)_a1 << 24) |
              ( (uint32_t)_r1 << 16) |
              ( (uint32_t)_b1 <<  8) |
              ( (uint32_t)_b1 );

Requirements

Requirement	Value
Target Platform	Windows
Header	directxpackedvector.h