I would like to ask if the LEDC library (that is compatible with Arduino IDE) supports value assignment to the variable "hpoint" in ESP32. Or, I must use a general C++ compiler to program ESP32 in order to control "hpoint"?
Hello @h-c, i believe you are referring to the LEDC device API by Espressif.
That is used internally by the Arduino core to provide the analogWrite() and tone() functions. If you do not use those Arduino functions, you should be able to call any LEDC API in your sketch.
Please note that any pin references in that API will need to be done with GPIOx numbers, not Dx numbers (check the pinout here for the mapping).
BR,
Luca