Cut out visuals underwater

If you wish to cut out any visuals from the underwater curtain, you have two possible solutions explained in this article. There are several use cases for this technique - we use it to display a side view of the interior of a submarine in our game.

Change renderQueue of a material

The most simple way is to manipulate the render queue of an object.

using UnityEngine;

public class SetRenderQueue : MonoBehaviour {
    [SerializeField]
    protected int[] m_queues = new int[] { 3000 };

    protected void Awake() {
        Material[] materials = GetComponent<Renderer>().materials;
        for (int i = 0; i < materials.Length && i < m_queues.Length; ++i) {
            materials[i].renderQueue = m_queues[i];
        }
    }
}

Just apply this MonoBehaviour to a object with a valid renderer and change the parameter so that the object will get rendered before the under water curtain.

Underwater mask

If you wish to cut out visuals with a mask, it’s getting a bit more complicated since this technique makes use of the stencil buffer. First you need to add this part into the UnderwaterCurtain.shader SubShader brackets:

Stencil {
	Ref 1
	Comp NotEqual
	Pass keep
}

Then create a new shader UnderWaterMask.shader:

Shader "Crest/Mask/Underwater Mask"
{
	SubShader{
		   Tags { "RenderType" = "Transparent" "ForceNoShadowCasting" = "True" }

		   Lighting Off

		   Stencil {
			   Ref 1
			   Comp always
			   Pass replace
		   }

		   CGPROGRAM
		   #pragma surface surf Lambert alpha nofog

		   struct Input {
			   fixed3 Albedo;
		   };

		   void surf(Input IN, inout SurfaceOutput o) {
			   o.Albedo = fixed3(1, 1, 1);
			   o.Alpha = 0;
		   }
		   ENDCG
	}
		FallBack "Diffuse"
}

Create a material with the new shader. Now any object with that material will cut out its own geometry from the underwater curtain and render the stuff that is behind it.