// scale is the width of the image in world space
TexturedRectangle3d::TexturedRectangle3d(V3d cen,V3d r,V3d d,RGBmp *img,float s) {
scale=s;
textureimg=img;
r=r.normalised()*scale;
d=d.normalised()*scale*(float)img->height/(float)img->width;
setupRectangle3d(cen-r/2.0-d/2.0,r,d);
}
void Ori::forcez(V3d nz) {
nz=nz.normalised();
y=V3d::normcross(x,nz).neg();
x=V3d::normcross(y,nz);
qz=nz;
}