Specializing Interfaces (Direct3D 11)
ID3DX11EffectVariable has a number of methods for casting the interface into the particular type of interface you need. The methods are of the form AsType and include a method for each type of effect variable (such as AsBlend, AsConstantBuffer etc..)
For example, suppose you have an effect with two global variables: time and a world transform.
float g_fTime; float4x4 g_mWorld;
Here is an example that gets these variables:
ID3DX11EffectVariable* g_pVariable; ID3DX11EffectMatrixVariable* g_pmWorld; ID3DX11EffectScalarVariable* g_pfTime; g_pVariable = g_pEffect11->GetVariableByName("g_mWorld"); g_pmWorld = g_pVariable->AsMatrix(); g_pVariable = g_pEffect11->GetVariableByName("g_fTime"); g_pfTime = g_pVariable->AsScalar();
By specializing the interfaces, you could reduce the code to a single call.
g_pmWorld = (g_pEffect11->GetVariableByName("g_mWorld"))->AsMatrix(); g_pfTime = (g_pEffect11->GetVariableByName("g_fTime"))->AsScalar();
Interfaces that inherit from ID3DX11EffectVariable also have these methods, but they have been designed to return invalid objects; only calls from ID3DX11EffectVariable return valid objects. Applications can test the returned object to see if it is valid by calling ID3DX11EffectVariable::IsValid.