void SetAlpha(float alpha){
		Vec4 param = mMaterial->GetMaterialParameter(3);
		mAlpha = param.w = alpha;
		mMaterial->SetMaterialParameter(3, param);
		mMaterialParamDest[3].w = alpha;
		mMaterialParamDest[2].w = alpha;
	}
	void PrepareInterpolation(float time, SkySpherePtr startFrom){
		MaterialPtr srcMaterial = mMaterial;
		if (startFrom)
			srcMaterial = startFrom->GetMaterial();
		for (int i = 0; i < 5; i++)
		{
			mMaterialParamCur[i] = srcMaterial->GetMaterialParameter(i);
		}

		mInterpolationTime = time;
		mCurInterpolationTime = 0;
		mInterpolating = true;
	}