Getting a position array uniform into the shader

I’ve updated the OGL Graphics code in the engine with the functions from this post:

Currently I’m setting the array uniform with this snippet:

    VariantVector varvec;
	varvec.Push(Vector3(0.0f, 0.5f, 0.0f));
	varvec.Push(Vector3(1.0f, 0.5f, 0.0f));
	varvec.Push(Vector3(1.0f, 0.5f, 1.0f));
	varvec.Push(Vector3(0.0f, 0.75f, 1.0f));
	grassMaterial->SetShaderParameter("ObjectPositionArray", varvec);

But how should I define the Vector3 array in the material definition? In the shader, I assume it’s just the usual GLSL opaque array declaration, but I can’t seem to find any material definitions that deal with arrays.