message: Set mean accumulator to highp for OpenGL backend.
diff: @@ -47,8 +47,14 @@ class Mean : public NodeShader {
  {"input_data_0_w", input->tensor.shape.w}};
  std::string source = R"(
  - vec4 sum = vec4(0.0);
  - float size = float($input_data_0_w$ * $input_data_0_h$);
  + // Shaders may be compiled with a precision hint mediump, which means that
  + // GLSL compiler may drop the size of float data type from 32 to 16 bits.
  + // If "sum" and "size" variables are 16bit floats, their values range
  + // become not enough for providing a good results accuracy. That is why
  + // their precision is forced to be 32bit by using highp qualifier.
  +
  + highp vec4 sum = vec4(0.0);
  + highp float size = float($input_data_0_w$ * $input_data_0_h$);
  for (int w = 0; w < $input_data_0_w$; w++) {
  for (int h = 0; h < $input_data_0_h$; h++) {
  sum += $input_data_0[w, h, gid.z]$;
  