   how texCUBE to locate the eye-point
  I found in the Nvidia glass hlsl example, there has texCUBE to calculate  float4 reflColor = texCUBE(EnvironmentMap, R); my question is if my eye point is not in the center of the cubemap, such as the reflect object is on the bottom of one plane side.how can I input the R direction, is there any funtion to help that.   