# Setting HLSL vectors from DX9 app

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Hello, I am finally getting to grip with shaders, using HLSL. I have the first of, I am sure, a string of queries.... I have learnt how to set a matrix in the shader, from the app, like the worldview matrix etc. Can I do the same thing with vectors? Heres the code from the shader I am trying to set, particualrly thelight direction:
float4x3 WorldView  : WORLDVIEW;
float4x4 Projection : PROJECTION;
float3 LightDir < string UIDirectional = "Light Direction"; > ;


And heres what I am attempting to do:
D3DXMATRIX WorldView;
D3DXMatrixMultiply( &WorldView, &I, g_camera->GetViewMatrixPtr() );
m_constantTable->SetMatrix( g_device, "WorldView", &WorldView);
m_constantTable->SetMatrix( g_device, "Projection", g_simulation->GetProjMatrixPtr() );
m_constantTable->SetVector( g_device, "LightDir", &tempLightDir );


...where tempLightDir is a D3DXVECTOR3. Is this possible? I am having problems (sorry, away from pc at the mo, so cant quite remember the error) Thanks Simon

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Vector's via the FX framework are considered to be float4 (D3DXVECTOR4) rather than float3 (D3DXVECTOR3). It matches the size of the constant registers.

You're best off packing the float3 up as a float4 on both ends. Bit awkward, but it works fine for me. Just remember to use Lightdir.xyz so that you don't get the unused component getting in the way [smile]

hth
Jack