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This lesson discusses how to make use of more advanced math functions provided in the DirectXMath library using existing SimpleMath types.

m_view = Matrix::CreateLookAt(Vector3(2.f, 2.f, 2.f), Vector3::Zero, Vector3::UnitY); m_proj = Matrix::CreatePerspectiveFieldOfView(XM_PI / 4.f, float(backBufferWidth) / float(backBufferHeight), 0.1f, 10.f);

would instead become:

m_view = XMMatrixLookAtLH(Vector3(2.f, 2.f, 2.f), Vector3::Zero, Vector3::UnitY); m_proj = XMMatrixPerspectiveFovLH( XM_PI / 4.f, float(backBufferWidth) / float(backBufferHeight), 0.1f, 10.f);

Many 'handed'

http://en.wikipedia.org/wiki/Right-hand_rule

Vector3 a(10.f, -.5f, 2.5f);

This compiles fine, but at runtime this actually executes a little bit of code to build the structure up. For a vector like this where all the values are literals and known at compile time, a more efficient way to code them is to use DirectXMath's

static const XMVECTORF32 s_a = { 10.f, -.5f, 2.5f, 0.f };

This becomes a vector laid out properly in data memory in your program ready for immediate use.

Options here include using:

- XMVECTORF32 which is 4x floats
- XMVECTORI32 which is 4x 32-bit ints
- XMVECTORU32 which is 4x 32-bit unsigned ints
- XMVECTORU8 which is 16x 8-bit unsigned ints

static const XMVECTORF32 s_lookat = { 2.f, 2.f, 2.f, 0.f }; m_view = Matrix::CreateLookAt( s_lookat, Vector3::Zero, Vector3::UnitY);

Vector3 fresnel = XMFresnelTerm( Vector4( a1, a2, a3, a4 ), Vector4( ri1, ri2, ri3, ri4 ) );

https://msdn.microsoft.com/en-us/library/windows/desktop/microsoft.directx_sdk.utilities.xmfresnelterm.aspx

For example, if we want to create the initData for a texture in DXGI_FORMAT_R9G9B9E5_SHAREDEXP format:

std::unique_ptr<DirectX::PackedVector::XMFLOAT3SE]]> data( new DirectX::PackedVector::XMFLOAT3SE[width * height] ); for ( size_t h = 0; h < height; ++h ) { for( size_t w = 0; w < width; ++w ) { Vector3 pixel; // our data from somewhere XMStoreFloat3SE( &data[ w * h ], pixel ); } }

https://msdn.microsoft.com/en-us/library/windows/desktop/ee418728.aspx

http://blogs.msdn.com/b/chuckw/archive/2013/10/24/directxmath-3-06.aspx

http://blogs.msdn.com/b/chuckw/archive/2014/12/12/known-issues-directxmath-3-06.aspx

http://blogs.msdn.com/b/chuckw/archive/2012/07/28/spherical-harmonics-math.aspx

http://blogs.msdn.com/b/chuckw/archive/2012/05/01/xdsp-h.aspx

http://blogs.msdn.com/b/chuckw/archive/2012/09/11/directxmath-sse-sse2-and-arm-neon.aspx

Last edited Jul 28, 2015 at 8:01 PM by walbourn, version 16