| inDirection | The direction vector towards the surface. |
| inNormal | The normal vector that defines the surface. |
法線を基準にしてベクトルの反射したベクトルを取得します。
This method calculates the reflection vector using the following formula: v = inDirection - 2 * inNormal * dot(inDirection inNormal). The inNormal vector defines a surface. A surface's normal is the vector that is perpendicular to
its surface. The inDirection vector is treated as a directional arrow coming into the surface.
The returned value is a vector of equal magnitude to inDirection but with its direction reflected.