A graphics card driver is the interface between the system and a specific graphics card. The driver is implemented as an add-on that's loaded by the Application Server when the Server starts up. Once the driver is loaded, it remains loaded until the machine is shut down.
Basic communication with a graphics card driver is performed through a single function called control_graphics_card(). The Application Server tells the driver which operation to perform by passing an opcode through this function. The driver can also implement a set of "hook" functions that the Server can invoke directly. (The locations of the hook functions are retrieved through a particular opcode passed to control_graphics_card().)
The Application Server is the primary "consumer" of a graphics card driver's functionality. However, the Game Kit, through its BWindowScreen class, can also access and modify the graphics card's frame buffer, and can call the card's accelerated graphics functions.
This chapter explains how to use control_graphics_card(), lists and describes the opcodes and hook functions, and explains how to build a graphics card driver:
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This documentation is valid for PCI-based cards only. |
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Last modified March 26, 1998.