XMVectorBaryCentric function (directxmath.h)

Article
07/27/2022

Returns a point in Barycentric coordinates, using the specified position vectors.

Syntax

XMVECTOR XM_CALLCONV XMVectorBaryCentric(
  [in] FXMVECTOR Position0,
  [in] FXMVECTOR Position1,
  [in] FXMVECTOR Position2,
  [in] float     f,
  [in] float     g
) noexcept;

Parameters

[in] Position0

First position.

[in] Position1

Second position.

[in] Position2

Third position.

[in] f

Weighting factor. See the remarks.

[in] g

Weighting factor. See the remarks.

Return value

Returns the Barycentric coordinates.

Remarks

This function provides a way to understand points in and around a triangle, independent of where the triangle is located. This function returns the resulting point by using the following equation: Position0> + f>(Position1-Position0>) + g>(Position2-Position0>).

Any point in the plane Position0>Position1>Position2> can be represented by the Barycentric coordinate (f>,g>), where f> controls how much Position1> gets weighted into the result, and g> controls how much Position2> gets weighted into the result. Lastly, 1-f>-g> controls how much Position0> gets weighted into the result.

Note the following relations.

If (f>=0 && g>=0 && 1-f-g>=0), the point is inside the triangle Position0>Position1>Position2>.
If (f==0 && g>=0 && 1-f-g>=0), the point is on the line Position0>Position2>.
If (f>=0 && g==0 && 1-f-g>=0), the point is on the line Position0>Position1>.
If (f>=0 && g>=0 && 1-f-g==0), the point is on the line Position1>Position2>.

Barycentric coordinates are a form of general coordinates. In this context, using Barycentric coordinates represents a change in coordinate systems. What holds true for Cartesian coordinates holds true for Barycentric coordinates.

Platform Requirements

Microsoft Visual Studio 2010 or Microsoft Visual Studio 2012 with the Windows SDK for Windows 8. Supported for Win32 desktop apps, Windows Store apps, and Windows Phone 8 apps.

Requirements

Requirement	Value
Target Platform	Windows
Header	directxmath.h (include DirectXMath.h)

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