# Using the Display Generator

As described in the graphics overview chapters, 3DO's display generator reads the contents of the frame buffer and sends a frame to the video display 30 times per second (or 60 times per second if you're using interleaved fields to display a stereoscopic image or to create a 320-by-480 display). This chapter gives you the programming details necessary to fill a frame to send to the display. You learn the Portfolio concepts of screen, bitmap, and screen group-and the graphics calls you use to create, modify, and display them. You also learn how to draw graphics primitives and place text in a bitmap, how to time graphics calls to match the frame rate, how to restore a fixed-frame background, how to turn pixel interpolation on and off, and other details of frame programming and display generator control. This chapter contains the following topics:

- An Overview of Frame Programming
- Opening the Graphics Folio
- Creating a Screen Group
- Creating a Custom VDL
- Setting a Screen Color Palette
- Displaying a Screen Group
- Rendering Into a Screen
- Refreshing Backgrounds with SPORT Transfers
- Display Timing Calls
- Controlling Pixel Interpolation
- Primary Data Structures
- Function Calls