Using Vertex Tweening (Direct3D 9)
To determine if Direct3D supports vertex tweening, check for the D3DVTXPCAPS_TWEENING flag in the VertexProcessingCaps member of the D3DCAPS9 structure. The following code example uses the IDirect3DDevice9::GetDeviceCaps method to determine if tweening is supported.
// This example assumes that m_pD3DDevice is
// a valid pointer to a IDirect3DDevice9 interface.
//
D3DCAPS9 d3dCaps;
m_pD3DDevice->GetDeviceCaps( &d3dCaps );
if( 0 != (d3dCaps.VertexProcessingCaps & D3DVTXPCAPS_TWEENING) )
// Vertex tweening is supported.
To use vector tweening, you must first set up a custom vertex type that uses a second normal or a second position. The following code example shows a sample declaration that includes both a second point and a second position.
struct TEX_VERTEX
{
D3DVECTOR position;
D3DVECTOR normal;
D3DVECTOR position2;
D3DVECTOR normal2;
};
//Create a vertex buffer with the type TEX_VERTEX.
The next step is to set the current declaration. The code example below shows how to do this.
// Create the shader declaration.
D3DVERTEXELEMENT9 decl[] =
{
{ 0, 0, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0 },
{ 0, 12, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_NORMAL, 0 },
{ 0, 24, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 1 },
{ 0, 36, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_NORMAL, 1 },
D3DDECL_END()
};
For more information about creating a custom vertex type and a vertex buffer, see Creating a Vertex Buffer (Direct3D 9).
Note
When vertex tweening is enabled, a second position or a second normal must be present in the current declaration.
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