How to get depth information in UE4/Unreal material

1. Obtain a fixed depth

1. Effect

2. Nodes in UE4

3. Node principle analysis

• 
• ScenceDepth can sample the depth of all model surfaces, as shown in red points B and E ;
• PixelDepth can only sample the depth of the surface of the model being drawn, as shown in the blue point B in the figure ;
• The absolute world position can only sample the pixel points on the surface of the model being drawn, as shown in point F;
• (Absolute world position - camera position: vector FA) * (ScenceDepth/PixelDepth: depth ratio) = vector DA;
• Vertex C is (0, 0, 80), which sets the height of the water surface/plane;
• camera position - point C = vector AC;
• Vector DA + vector AC = vector CD;
• The Mask mask takes the Z value of the vector CD, which is the yellow h value in the figure , and the depth h obtained in this way will be constant at another angle;
• The purpose of the follow-up calculation is to make h take a value between 0-1;

2. How to obtain the depth that changes with the viewing angle

1. The effect is as shown in the figure

2. Nodes in UE4

 3. Analysis of node principle

• DepthFade node: Simulate the fusion of transparent objects and non-transparent objects when they are in contact;
• FadeDistance: Control the speed of fading, the smaller the distance, the faster the fading;