N64® Functions Menu

al - Audio Library Functions
gDP - DP GBI Macros
gdSP - General GBI Macros
gSP - SP GBI Macros
gt - Turbo Microcode RDP
gu - Graphics Utilities
Math - Math Functions
nuSys - NuSystem
os - N64 Operating System
sp - Sprite Library Functions
uh - Host to Target IO
64DD - N64 Disk Drive

Nintendo® Confidential

## gdSPDefLookAt

Syntax

    #include "gbi.h"
    typedef union {
    Light    l[2];
    } LookAt;
    LookAt gdSPDefLookAt(signed char rightx,
         signed char righty,
         signed char rightz,
         signed char upx,
         signed char upy,
         signed char upz)

Arguments

- rightx, righty, rightz are the x, y, z components in viewing space of x direction in screen space
- upx, upy, upz are the x, y, z components in viewing space of y direction in screen space

Explanation
It loads the x and y screen space coordinate directions into a LookAt structure. The x and y direction unit vectors, where components are expressed in the viewing space, must be converted to a signed 8-bit fixed-point representation. Each component c must undergo the conversion:
((int) MIN(((c) * (128.0)),127.0) 0xff)
The LookAt structure serves as input for the gSPLookAt macro, used in the set up process for specular highlights or reflection mapping.
See Also
gSPLookAt

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 March 1998