PS2 Linux Programming
Introduction
This short tutorial introduces the so-called ADC bit which is used to control the rendering of primitive data. The ADC bit is packed with the vertex data, and it's state (0 or 1) tells the graphics synthesiser whether the primitive associated with the vertex should be rendered or not.
Background
The position of a vertex in space is packed into a 128 bit qword for transmission to the graphics synthesiser as shown in Figure 1 below. The important information here is the ADC bit which is the flag used to control the rendering with this vertex. The X, Y and Z fields define the position of the vertex in space.
Figure 1
If the ADC bit is set to 1, a so-called drawing kick is not performed by the graphics synthesiser for this vertex and the primitive associated with this vertex is not rendered. If the ADC bit is set to 0, a drawing kick is performed for this vertex and the primitive associated with this vertex is rendered by the graphics synthesiser.
Conclusion
This short tutorial introduces the purpose of the ADC bit. The ADC bit will be used extensively in future tutorials for controlling effects such as back face culling and frustum clipping.
Dr Henry S Fortuna
University of Abertay Dundee