message: Fix mediump issue on mobile
diff: @@ -57,7 +57,7 @@ float coneTraceOcclusion(in ConeTraceSetup setup, const sampler2D depthTexture)
  // init trace distance and sample radius
  highp float invLinearDepth = 1.0 / -setup.vsStartPos.z;
  - float ssTracedDistance = max(setup.coneTraceParams.z, minTraceDistance) * invLinearDepth;
  + highp float ssTracedDistance = max(setup.coneTraceParams.z, minTraceDistance) * invLinearDepth;
  float ssSampleRadius = setup.coneTraceParams.y * ssTracedDistance;
  float ssEndRadius = setup.coneTraceParams.y * ssConeLength;
  @@ -81,11 +81,11 @@ float coneTraceOcclusion(in ConeTraceSetup setup, const sampler2D depthTexture)
  // sample depth buffer
  highp vec2 ssSamplePos = perpConeDir * ssJitteredSampleRadius + ssConeDirection * ssJitteredTracedDistance + ssStartPos;
  - highp float vsSampleDepthLinear = -sampleDepthLinear(depthTexture, ssSamplePos, 0.0, setup.depthParams);
  + float vsSampleDepthLinear = -sampleDepthLinear(depthTexture, ssSamplePos, 0.0, setup.depthParams);
  // calculate depth of cone center
  float ratio = ssJitteredTracedDistance * ssInvConeLength;
  - highp float vsConeAxisDepth = 1.0 / mix(ssStartInvW, ssEndInvW, ratio);
  + float vsConeAxisDepth = 1.0 / mix(ssStartInvW, ssEndInvW, ratio);
  // calculate depth range of cone slice
  float vsConeRadius = (ratio * vsEndRadius) * vsConeAxisDepth;
  