I'm working on a portal game with Unity. For the portal camera to see the world correctly, I do a matrix calculation like the one I see in github. https://github.com/pr0g/unity-porta...alsWithRenderTargets/Assets/Scripts/Portal.cs But when I do, the distortion effect of unity's "Glass Refractive" material deteriorates. The main camera is rendering correctly. However, the portal camera does not show the distortion effect when I use the projection matrix calculation. If I do not calculate the projection matrix, the distortion effect is visible, but this time, objects such as walls in front of the camera pass. Because the projection matrix does not calculate the back of the portal does not cut. When I use the matrix calculation in unity's water script for projection matrix calculation, the result does not change again. Since I don't understand the cause of this problem, I can't predict what kind of problem it can cause on different shaders. Does anyone have any idea about this?