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Working with D3DXMath

D3DXMath is a math helper library for Direct3D applications. D3DXMath is long-standing, is included in D3DX 9 and D3DX 10, and dates back to older versions of DirectX as well.

Note  The D3DX utility library (D3DX 9, D3DX 10, and D3DX 11) is deprecated for Windows 8, so we highly recommended that you migrate to DirectXMath rather than using D3DXMath.

DirectXMath shares much of the same functionality in D3DXMath, and internally D3DXMath includes a number of processor-specific optimizations. The key difference is that D3DXMath is hosted in the D3DX9*.DLLs and D3DX10*.DLLs, and very few of the functions are inlined. The DirectXMath Library calling convention is explicitly SIMD friendly, whereas D3DXMath has to perform load and store conversions to implement SIMD optimization.

Mixing DirectXMath and D3DXMath

D3DX11 does not contain D3DXMath, and in general we recommend using DirectXMath instead. However, you are free to continue to link to D3DX9 and/or D3DX10 in your application, and therefore you could continue to use D3DXMath or use both D3DXMath and DirectXMath in your application at the same time.

It is in general safe to cast an XMVECTOR* to a function that takes D3DXVECTOR4* or to cast an XMMATRIX* to a function that takes D3DXMATRIX*. The inverse is, however, not generally safe because XMVECTOR and XMMATRIX must be 16-byte aligned, while D3DXVECTOR4 and D3DXMATRIX have no such requirement. Failure to adhere to this requirement can result in invalid alignment exceptions at runtime.

It is safe to cast an XMVECTOR* to a function that takes D3DXVECTOR2* or D3DXVECTOR3*, but not vice-versa. Both alignment concerns and the fact that D3DXVECTOR2 and D3DXVECTOR3 are smaller structures make this an unsafe operation.

Note  D3DX (and therefore D3DXMath) is considered legacy, and is not available to Windows Store apps that run on Windows 8 and is not included in the Windows 8 SDK for desktop apps.

Using DirectXMath with Direct3D

Both DirectXMath and D3DXMath are optional when working with Direct3D. Direct3D 9 defined D3DMATRIX and D3DCOLOR as part of the Direct3D API in support of the (now legacy) fixed-function pipeline. D3DXMath in D3DX9 extends these Direct3D 9 types with common graphics math operations. For Direct3D 10.x and Direct3D 11, the API uses only the programmable pipeline so there is no API-specific structure for either matrices or color values. When the newer APIs require a color value, they take an explicit array of float values or a generic buffer of constant data that is interpreted by the HLSL shader. HLSL itself can support either row-major or column-major matrix formats, so the layout is entirely up to you (for more info, see HLSL, Matrix Ordering; if you use column-major matrix formats in your shaders, you need to transpose the DirectXMath matrix data as you place it into your constant buffer structures). While optional, the DirectXMath and D3DXMath libraries both provide common graphics related functionality, and are therefore extremely convenient when doing Direct3D programming.

It is safe to cast an XMVECTOR* to a D3DVECTOR* or XMMATRIX* to D3DMATRIX* since Direct3D 9 makes no alignment assumptions about the incoming data structure. It is also safe to cast XMCOLOR to D3DCOLOR. You can convert a 4-float representation of color to XMCOLOR via XMStoreColor() to get the 8:8:8:8 32-bit DWORD that is equivalent to D3DCOLOR.

When working with Direct3D 10.x or Direct3D 11, you will typically use DirectXMath types to build a structure for each of your constant buffers, and in those cases it largely depends on your ability to control the alignment to make these efficient, or to use XMStore*() operations to convert XMVECTOR and XMMATRIX data to the correct data types. When calling Direct3D 10.x or Direct3D 11 APIs that require a float[4] array of color values, you can cast an XMVECTOR* or XMFLOAT4* containing the color data.

Porting from D3DXMath

D3DXMath TypeDirectXMath Equivalent
D3DXFLOAT16 HALF
D3DXMATRIXA16 XMMATRIX or XMFLOAT4X4A

D3DXQUATERNION

D3DXPLANE

D3DXCOLOR

XMVECTOR is used rather than having unique types, so you will likely need to use an XMFLOAT4

Note  D3DXQUATERNION::operator * calls the D3DXQuaternionMultiply function, which multiplies two quaternions. But, unless you explicitly use the XMQuaternionMultiply function, you get an incorrect answer when you use XMVECTOR::operator * on a quaternion.

D3DXVECTOR2 XMFLOAT2
D3DXVECTOR2_16F XMHALF2
D3DXVECTOR3 XMFLOAT3
D3DXVECTOR4 XMFLOAT4

(or if you can guarantee the data is 16-byte aligned, XMVECTOR or XMFLOAT4A )

D3DXVECTOR4_16F XMHALF4

 

Note  There is no direct equivalent to D3DXVECTOR3_16F in XNAMath.

D3DXMath MacroDirectXMath Equivalent
D3DX_PI XM_PI
D3DX_1BYPI XM_1DIVPI
D3DXToRadian XMConvertToRadians
D3DXToDegree XMConvertToDegrees

 

D3DXMath FunctionDirectXMath Equivalent
D3DXBoxBoundProbe BoundingBox::Intersects(XMVECTOR, XMVECTOR, float&)
D3DXComputeBoundingBox BoundingBox::CreateFromPoints
D3DXComputeBoundingSphere BoundingSphere::CreateFromPoints
D3DXSphereBoundProbe BoundingSphere::Intersects(XMVECTOR, XMVECTOR, float&)
D3DXIntersectTriFunction TriangleTests::Intersects
D3DXFloat32To16Array XMConvertFloatToHalfStream
D3DXFloat16To32Array XMConvertHalfToFloatStream
D3DXVec2Length XMVector2Length or XMVector2LengthEst
D3DXVec2LengthSq XMVector2LengthSq
D3DXVec2Dot XMVector2Dot
D3DXVec2CCW XMVector2Cross
D3DXVec2Add XMVectorAdd
D3DXVec2Subtract XMVectorSubtract
D3DXVec2Minimize XMVectorMin
D3DXVec2Maximize XMVectorMax
D3DXVec2Scale XMVectorScale
D3DXVec2Lerp XMVectorLerp or XMVectorLerpV
D3DXVec2Normalize XMVector2Normalize or XMVector2NormalizeEst
D3DXVec2Hermite XMVectorHermite or XMVectorHermiteV
D3DXVec2CatmullRom XMVectorCatmullRom or XMVectorCatmullRomV
D3DXVec2BaryCentric XMVectorBaryCentric or XMVectorBaryCentricV
D3DXVec2Transform XMVector2Transform
D3DXVec2TransformCoord XMVector2TransformCoord
D3DXVec2TransformNormal XMVector2TransformNormal
D3DXVec2TransformArray XMVector2TransformStream
D3DXVec2TransformCoordArray XMVector2TransformCoordStream
D3DXVec2TransformNormalArray XMVector2TransformNormalStream
D3DXVec3Length XMVector3Length or XMVector3LengthEst
D3DXVec3LengthSq XMVector3LengthSq
D3DXVec3Dot XMVector3Dot
D3DXVec3Cross XMVector3Cross
D3DXVec3Add XMVectorAdd
D3DXVec3Subtract XMVectorSubtract
D3DXVec3Minimize XMVectorMin
D3DXVec3Maximize XMVectorMax
D3DXVec3Scale XMVectorScale
D3DXVec3Lerp XMVectorLerp or XMVectorLerpV
D3DXVec3Normalize XMVector3Normalize or XMVector3NormalizeEst
D3DXVec3Hermite XMVectorHermite or XMVectorHermiteV
D3DXVec3CatmullRom XMVectorCatmullRom or XMVectorCatmullRomV
D3DXVec3BaryCentric XMVectorBaryCentric or XMVectorBaryCentricV
D3DXVec3Transform XMVector3Transform
D3DXVec3TransformCoord XMVector3TransformCoord
D3DXVec3TransformNormal XMVector3TransformNormal
D3DXVec3TransformArray XMVector3TransformStream
D3DXVec3TransformCoordArray XMVector3TransformCoordStream
D3DXVec3TransformNormalArray XMVector3TransformNormalStream
D3DXVec3Project XMVector3Project
D3DXVec3Unproject XMVector3Unproject
D3DXVec3ProjectArray XMVector3ProjectStream
D3DXVec3UnprojectArray XMVector3UnprojectStream
D3DXVec4Length XMVector4Length or XMVector4LengthEst
D3DXVec4LengthSq XMVector4LengthSq
D3DXVec4Dot XMVector4Dot
D3DXVec4Add XMVectorAdd
D3DXVec4Subtract XMVectorSubtract
D3DXVec4Minimize XMVectorMin
D3DXVec4Maximize XMVectorMax
D3DXVec4Scale XMVectorScale
D3DXVec4Lerp XMVectorLerp or XMVectorLerpV
D3DXVec4Cross XMVector4Cross
D3DXVec4Normalize XMVector4Normalize or XMVector4NormalizeEst
D3DXVec4Hermite XMVectorHermite or XMVectorHermiteV
D3DXVec4CatmullRom XMVectorCatmullRom or XMVectorCatmullRomV
D3DXVec4BaryCentric XMVectorBaryCentric or XMVectorBaryCentricV
D3DXVec4Transform XMVector4Transform
D3DXVec4TransformArray XMVector4TransformStream
D3DXMatrixIdentity XMMatrixIdentity
D3DXMatrixDeterminant XMMatrixDeterminant
D3DXMatrixDecompose XMMatrixDecompose
D3DXMatrixTranspose XMMatrixTranspose
D3DXMatrixMultiply XMMatrixMultiply
D3DXMatrixMultiplyTranspose XMMatrixMultiplyTranspose
D3DXMatrixInverse XMMatrixInverse
D3DXMatrixScaling XMMatrixScaling
D3DXMatrixTranslation XMMatrixTranslation
D3DXMatrixRotationX XMMatrixRotationX
D3DXMatrixRotationY XMMatrixRotationY
D3DXMatrixRotationZ XMMatrixRotationZ
D3DXMatrixRotationAxis XMMatrixRotationAxis
D3DXMatrixRotationQuaternion XMMatrixRotationQuaternion
D3DXMatrixRotationYawPitchRoll XMMatrixRotationRollPitchYaw (Note the order of parameters is different: D3DXMatrixRotationYawPitchRoll takes yaw, pitch, roll, XMMatrixRotationRollPitchYaw takes pitch, yaw, roll)
D3DXMatrixTransformation XMMatrixTransformation
D3DXMatrixTransformation2D XMMatrixTransformation2D
D3DXMatrixAffineTransformation XMMatrixAffineTransformation
D3DXMatrixAffineTransformation2D XMMatrixAffineTransformation2D
D3DXMatrixLookAtRH XMMatrixLookAtRH
D3DXMatrixLookAtLH XMMatrixLookAtLH
D3DXMatrixPerspectiveRH XMMatrixPerspectiveRH
D3DXMatrixPerspectiveLH XMMatrixPerspectiveLH
D3DXMatrixPerspectiveFovRH XMMatrixPerspectiveFovRH
D3DXMatrixPerspectiveFovLH XMMatrixPerspectiveFovLH
D3DXMatrixPerspectiveOffCenterRH XMMatrixPerspectiveOffCenterRH
D3DXMatrixPerspectiveOffCenterLH XMMatrixPerspectiveOffCenterLH
D3DXMatrixOrthoRH XMMatrixOrthographicRH
D3DXMatrixOrthoLH XMMatrixOrthographicLH
D3DXMatrixOrthoOffCenterRH XMMatrixOrthographicOffCenterRH
D3DXMatrixOrthoOffCenterLH XMMatrixOrthographicOffCenterLH
D3DXMatrixShadow XMMatrixShadow
D3DXMatrixReflect XMMatrixReflect
D3DXQuaternionLength XMQuaternionLength
D3DXQuaternionLengthSq XMQuaternionLengthSq
D3DXQuaternionDot XMQuaternionDot
D3DXQuaternionIdentity XMQuaternionIdentity
D3DXQuaternionIsIdentity XMQuaternionIsIdentity
D3DXQuaternionConjugate XMQuaternionConjugate
D3DXQuaternionToAxisAngle XMQuaternionToAxisAngle
D3DXQuaternionRotationMatrix XMQuaternionRotationMatrix
D3DXQuaternionRotationAxis XMQuaternionRotationAxis
D3DXQuaternionRotationYawPitchRoll XMQuaternionRotationRollPitchYaw (Note the order of parameters is different: D3DXQuaternionRotationYawPitchRoll takes yaw, pitch, roll, XMQuaternionRotationRollPitchYaw takes pitch, yaw, roll)
D3DXQuaternionMultiply XMQuaternionMultiply
D3DXQuaternionNormalize XMQuaternionNormalize or XMQuaternionNormalizeEst
D3DXQuaternionInverse XMQuaternionInverse
D3DXQuaternionLn XMQuaternionLn
D3DXQuaternionExp XMQuaternionExp
D3DXQuaternionSlerp XMQuaternionSlerp or XMQuaternionSlerpV
D3DXQuaternionSquad XMQuaternionSquad or XMQuaternionSquadV
D3DXQuaternionSquadSetup XMQuaternionSquadSetup
D3DXQuaternionBaryCentric XMQuaternionBaryCentric or XMQuaternionBaryCentricV
D3DXPlaneDot XMPlaneDot
D3DXPlaneDotCoord XMPlaneDotCoord
D3DXPlaneDotNormal XMPlaneDotNormal
D3DXPlaneScale XMVectorScale
D3DXPlaneNormalize XMPlaneNormalize or XMPlaneNormalizeEst
D3DXPlaneIntersectLine XMPlaneIntersectLine
D3DXPlaneFromPointNormal XMPlaneFromPointNormal
D3DXPlaneFromPoints XMPlaneFromPoints
D3DXPlaneTransform XMPlaneTransform
D3DXPlaneTransformArray XMPlaneTransformStream
D3DXColorNegative XMColorNegative
D3DXColorAdd XMVectorAdd
D3DXColorSubtract XMVectorSubtract
D3DXColorScale XMVectorScale
D3DXColorModulate XMColorModulate
D3DXColorLerp XMVectorLerp or XMVectorLerpV
D3DXColorAdjustSaturation XMColorAdjustSaturation
D3DXColorAdjustContrast XMColorAdjustContrast
D3DXFresnelTerm XMFresnelTerm

 

Note  Spherical Harmonics functions for DirectXMath are available separately. There is no DirectXMath equivalent to ID3DXMatrixStack.

 

 

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