Vsync, hsync, vblank

Vsync: vertical synchronization, which is used to synchronize the number of frames with the display. simply put, the rendering process of vsync is enabled. The number of frames does not exceed the number of frames on the monitor, and a synchronization will be executed. the place for synchronization is where the last line of scanning is completed and the first line of scanning is prepared.

Hsync: horizonal synchronization. Compared with vsync, the unit of synchronization is reduced from frame to row, which means that the operation does not appear in the middle of a row, but is synchronized to the next row.

Vblank: after the last line of the display is scanned, You need to return to the upper left corner. This process is called vblank, also known as vertical blank interval, because the scanning line becomes blank, to prevent a diagonal line from being displayed on the screen.