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plane

A plane is a page arranged in a size of horizontal 1 x vertical 1, horizontal 2 x vertical 1, horizontal 2 x vertical 2. When a plane is composed of multiple pages, the page data (pattern name data table) that make up the plane must be stored continuously in VRAM.
The plane data is passed to the higher-level map and rearranged.

Figure 8-13 Plain image

Note) All are displayed vertically and horizontally.

To set the plane size in SGL, use the library functions “slPlaneNbg0-3” and “slPlaneRA, B”.

[void slPlaneNbg0-3 (Uint16 plane_size);]

[void slPlaneRA, RB (Uint16 plane_size);]

Set the plain size of each scroll surface.
For the parameter, substitute the value in the table below corresponding to the plane size.

Table 8-12 “slPlaneNbg0-3”, “slPlaneRA, RB” parameter substitution values ​​(plane_size)

Note) The values ​​in the above table are defined in “sl_def.h” included with the system.

Restriction on plane size specification by reduction setting

If you set the normal reduction screen NBG0, NBG1 to 1/4 times the range that can be reduced, do not set the plane size of the scroll screen to 2 x 2 pages. This is because the map size when the shrinkable range is set to 1/4 times is different from the normal size.
1 x 1, 2 x 1 pages can be used without problems.
Refer to “HARDWARE MANUAL vol.2: VDP2 User's Manual” for details on the plane size specification limit.

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