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osViSetMode
Format#include <ultra64.h>
void osViSetMode(OSViMode *mode);
What This Function Does
It is one of the following 16 management functions for the video interface (VI):
- osViGetStatus
- osViGetCurrentMode
- osViGetCurrentLine
- osViGetCurrentField
- osViGetCurrentFramebuffer
- osViGetNextFramebuffer
- osViSetMode
- osViSetEvent
- osViSetSpecialFeatures
- osViSetXScale
- osViSetYScale
- osViSwapBuffer
- osViBlack
- osViFade
- osViRepeatLine
- osCreateViManager
For general information about the VI and its supported modes, codes, and functions, see the osVi page. The general information applies to each of the VI management functions and you should understood it before using any of the VI functions. All 16 functions are described, so you can see how they all work together to manage the VI.
Currently, there is a global VI mode table (osViModeTable) that contains register settings for all 42 modes. You can use the osViSetMode function to register one of these modes with the VI to be used at the next vertical retrace. This function simply overwrites all the VI registers with data from the location pointed to by the mode argument, which is a pointer into osViModeTable. All previous settings (such as XY scaling and gamma correction) are reset. For example, to register the NTSC, low resolution, anti-aliased, non-interlaced, 16-bit mode with the VI, use this code:
osViSetMode(osViModeTable[OS_VI_NTSC_LAN1]);
For storage efficiency, the global VI mode table is divided into 42 separate mode structures with each structure globally defined in a separate source file. These structures are externally declared in <os.h>. To gain access to the equivalent mode mentioned above, use this code:
osViSetMode(osViModeNtscLan1);
When Nintendo 64 powers on, the boot code sets the timing to NTSC, PAL, or MPAL and blanks out the video. The call to osCreateViManager initializes the video to LAN1 (in either NTSC, PAL, or MPAL mode) and also blanks out the video. The first time video is enabled is when osViSetMode is called. To keep the screen blank until after the first use of osViSwapBuffer, call osViBlack(TRUE) immediately after the osViSetMode call. Then call osViBlack(FALSE) right before the first call to osViSwapBuffer.
Notes
The VI manager must be started at the beginning of the program so that vertical retrace interrupts can be serviced as quickly as possible. Note that osViSetMode resets all current settings such as X-Y scaling and special features such as gamma to the default values defined in the global mode table.
The video back-end filter can only execute an anti-aliasing filter or a dither filter, but not both simultaneously. This is especially visible on "billboard" cutouts in texture edge mode during magnification in the region of the cutout where alpha goes from 1 to 0. In this region, the dither pattern is visible because the back-end filter executes an anti-alias filter (due to partial coverage) and turns off the dither filter.
This problem also occurs on anti-aliased silhouette edges of polygons, but it is not obvious due to the small width of the partially covered region.
See Also
osViGetStatus
osViGetCurrentMode
osViGetCurrentLine
osViGetCurrentField
osViGetCurrentFramebuffer
osViGetNextFramebuffer
osViSetEvent
osViSetSpecialFeatures
osViSetXScale
osViSetYScale
osViSwapBuffer
osViBlack
osViFade
osViRepeatLine
osCreateViManager
osSetEventMesg
osGetTime
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Nintendo® Confidential Warning: all information in this document is confidential and covered by a non-disclosure agreement. You are responsible for keeping this information confidential and protected. Nintendo will vigorously enforce this responsibility. Copyright © 1998 Nintendo of America Inc. All rights reserved Nintendo and N64 are registered trademarks of Nintendo Last updated January 1998 |