cocos-creator-template/assets/effects/pipeline/post-process/chunks/depth.chunk

// Copyright (c) 2017-2020 Xiamen Yaji Software Co., Ltd.
#include <common/common-define>
#include <common/math/coordinates>

#pragma rate DepthTex pass
uniform sampler2D DepthTex; //Sample_Point_Clamp
float GetDepthFromTex(vec2 uv) {
  return texture(DepthTex, saturate(uv)).r;
}

float GetLinearDepthWithProj(vec2 uv, mat4 proj) {
  float depthHS = GetDepthFromTex(uv) * 2.0 - 1.0; // -1.0 ~ +1.0
  return -GetCameraDepthRH(depthHS, proj);
}