View Full Version : Help! Converting Angles to Vectors

El Jefe
06-09-2000, 06:07 AM
I'm trying to get a set of normalized vectors ( forward, right, up ) from the current camera angles ( yaw, pitch, roll ) and am having some problems. I found some code to do this in the Quake I source code, but it doesn't quite seem to work because the Y and Z axis are swapped in Quake ( Z is up ) relative to how they would be in OpenGL ( Y is up ) My math skills aren't great, so perhaps the solution is easy??

Here's the Quake code if that will help:

void AngleVectors( vec3_t ang, vec3_t fwd, vec3_t right, vec3_t up) {
float angle;
float sr, sp, sy, cr, cp, cy;

angle = ang[YAW] * (M_PI*2/360);
sy = sin(angle);
cy = cos(angle);
angle = ang[PITCH] * (M_PI*2/360);
sp = sin(angle);
cp = cos(angle);
angle = ang[ROLL] * (M_PI*2/360);
sr = sin(angle);
cr = cos(angle);

if( fwd ) {
forward[0] = cp*cy;
forward[1] = cp*sy;
forward[2] = -sp;
if( right ) {
right[0] = (-1*sr*sp*cy+-1*cr*-sy);
right[1] = (-1*sr*sp*sy+-1*cr*cy);
right[2] = -1*sr*cp;
if( up ) {
up[0] = (cr*sp*cy+-sr*-sy);
up[1] = (cr*sp*sy+-sr*cy);
up[2] = cr*cp;

Thanks in advance.

06-09-2000, 06:10 AM
Just look up an Euler-to-matrix conversion algo; I think there's one in the Hexapod FAQ. The first three columns of the result matrix are the normalized positive X, Y, Z axes.

El Jefe
06-09-2000, 01:02 PM
Thanks, I did a search for hexapod, but didn't exactly find the site you are refering to. Do you happen to have the URL?

Thanks much.

06-10-2000, 05:29 AM
Many thanks to anyone who offered tips on how to solve this problem.
I found the Euler Angles rotation matrix at: http://cadd.cern.ch/cad_geant_int/ddt_long/node11.html

but I had to do some reworking for it to work?? Anyway, if anyone would like the solution I used, I guess let me know?

Thanks again!
El Jefe