Multi-viewpoint　retina　projection　displays　(RPD)　with　an　expanded　visible　range　have　been　utilized　in　recent　augmented　reality　(AR)　systems　to　address　the　vergence-accommodation　conflict　(VAC)　by　providing　a　long　depth　of　field　(DOF).　However,　these　fixed　multi-viewpoint　RPD　systems　still　face　a　common　critical　challenge　of　imaging　overlap　or　discontinuity　when　eyes　rotate　or　under　varying　ambient　light.　To　address　this,　an　RPD　AR　system　featuring　switchable　ultra-dense　viewpoints　is　presented,　enabled　by　a　photo-alignment　liquid　crystal　Dammann　grating　(p-LCDG).　The　number　of　viewpoints　reaches　49,　which　forms　an　ultra-high　density　of　diffraction　lattice　in　front　of　the　pupil　with　a　record　high　rotation　precision　of　1.28　degrees/viewpoint,　allowing　for　a　substantial　range　of　36　mm2.　More　importantly,　the　spacing　of　adjacent　viewpoints　is　0.532　mm,　much　smaller　than　the　minimum　radius　of　the　pupil　(approximate　to　1　mm).　To　facilitate　viewpoint　switching,　a　light　selector　is　implemented,　ensuring　that　only　the　light　from　a　specific　viewpoint　reaches　the　eye,　which　effectively　eliminates　the　image　missing　or　discontinuity.　By　combining　eye　tracking　technology,　the　viewer　can　consistently　perceive　a　singular　and　clear　image　from　the　proposed　RPD　system,　achieving　seamless　switching　of　viewpoints.　This　innovative　design　paves　the　way　for　high-performance　RPDs　in　AR　applications.