HDRP Custom Pass Shader Get world coordinates and near clipping plane coordinates

获取世界坐标

posInputThe coordinates need to be added to the coordinates of the camera,honey juice pit…

float3 ws = _WorldSpaceCameraPos + posInput.positionWS;

Get the near clipping plane coordinates

用到函数 ComputeWorldSpacePosition().

float3 nearPositionWS = ComputeWorldSpacePosition(posInput.positionNDC, 1, UNITY_MATRIX_I_VP);
nearPositionWS += _WorldSpaceCameraPos; 

The internal implementation of this function is of course still usedNDCCoordinates push world space coordinates,But the parameters passed in here are screen coordinatesUV.（Although he named itNDC- -,But it's actually screen coordinatesUV,左下角(0, 0) , 右上角(1, 1)）

另外,Here the near plane depth is 1,远平面是0.

This link details how to use itNDCCoordinates and depths derive world space coordinates.上善若水_2019-Reconstructs the coordinates of screen pixels in the world from depth information-简书

Implemented in vertex shader

注释掉引用 CustomPassCommon.hlsl 的那一行,把 CustomPassCommon.hlsl Copy the content inside to your shader,Unlock vertex shader.

Change the code in the vertex shader to look like this

    struct Varyings
    {
    
        float4 positionCS : SV_POSITION;
        // Add a register
        float3 positionWS : TEXCOORD0;
        UNITY_VERTEX_OUTPUT_STEREO
    };

    Varyings Vert(Attributes input)
    {
    
        Varyings output;
        UNITY_SETUP_INSTANCE_ID(input);
        UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(output);
        // 注释掉
        // output.positionCS = GetFullScreenTriangleVertexPosition(input.vertexID, UNITY_RAW_FAR_CLIP_VALUE);
        
        // 改成
        float2 uv = float2((input.vertexID << 1) & 2, input.vertexID & 2);
        output.positionCS =  float4(uv * 2.0 - 1.0, UNITY_RAW_FAR_CLIP_VALUE, 1.0);
        
        float3 nearPositionWS = ComputeWorldSpacePosition(uv, 1, UNITY_MATRIX_I_VP);
        nearPositionWS += _WorldSpaceCameraPos; 
        output.positionWS = nearPositionWS; 
        return output;
    }