Using LDR sensor with Arduino for a projection mapping pop up book project

Hello Friends ,
We are trying to build a projection mapping pop up book. we are planning to use LDR sensors to detect the change of page and do the projection accordingly but as we are very new with arduino we are confused about where to put the sensors and do we have some available libraries which can take the signal form LDr sensor and trigger different projection according to different page.

plz help

we did some research and found out this "When the user turns the page of the book, light sensors embedded in the podium, detect the change and send switch state values to an arduino. The Arduino sends the values to processing,which in turns turns these values into OSC signals and send them to Resolume, a graphic and VJ program application. "

but if someone can make it more simpler and tell us about the libraries and mechanism

u dont need a library for a LDR. Make a voltage divider with a resistor, read the analog signal.
This signal will change as light changes. Your 'trigger' can be when the read value reaches a predefined setpoint