Path: utzoo!mnetor!tmsoft!masnet!canremote!mark.williston
From: mark.williston@canremote.uucp (MARK WILLISTON)
Newsgroups: comp.graphics
Subject: Re: 3-D Rotation Algorithm
Message-ID: <89101604163968@masnet.uucp>
Date: 16 Oct 89 00:46:00 GMT
Organization: Canada Remote Systems Limited, Mississauga, ON, Canada
Lines: 48

int x, y, z, xa, ya, za, angle;
double d, r, convert=3.141593/180;
int Sin[360], Cos[360];

void rot(void)
{
	int t;
  t = ((Cos[xa]*x)>>8)-((Sin[xa]*z)>>8); /* Rotate around the X Axis */
  z = ((Sin[xa]*x)>>8)+((Cos[xa]*z)>>8);
  x = t;
  t = ((Cos[ya]*y)>>8)+((Sin[ya]*z)>>8); /* Rotate around the Y Axis */
  z =-((Sin[ya]*y)>>8)+((Cos[ya]*z)>>8);
	y	=  t;
  t = ((Cos[za]*x)>>8)+((Sin[za]*y)>>8); /* Rotate around the Z Axis */
  y =-((Sin[za]*x)>>8)+((Cos[za]*y)>>8);
  x = t;
}

void main(void)
{
	Call_Set_Vid_Mode( Your_Mode );
  for(angle=0; angle<360; angle++)  /* table of shiftwise degs */
	{
		r=(double)angle*convert;
		Cos[angle]=(int)(cos(r)*256);
		Sin[angle]=(int)(sin(r)*256);
	}

	while(you_want_to_rotate_points)
	{
		x=xval;            /* fill x from somewhere! */
		y=yval;            /* fill y from somewhere! */
		z=zval;            /* fill z from somewhere! */
				/*
					With this pseudodegree method, x, y and z
					must not overflow	the integer. This works
					well with small numbers.  Using long ints
					would give a larger capacity.
				*/
		rot();  /* rotate them */
		x+=screen_centre;  /* bring the point into view */
		y+=screen_centre;  /* bring the point into view */
		CallYourPlot(x,y,color);
	}

Mark Williston
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 * QDeLuxe 1.10 #3694  <\/>ark </\>illiston - Author of 2-Bit Poker [EGA]