bool csReversibleTransform::LookAtGeneric (
const csVector3 &v,
const csVector3 &upNeg,
csVector3& w1,
csVector3& w2,
csVector3& w3)
{
csVector3 up = -upNeg;
w3 = v;
float sqr;
sqr = v * v;
if (sqr > SMALL_EPSILON)
{
w3 *= csQisqrt (sqr);
w1 = w3 % up;
sqr = w1 * w1;
if (sqr < SMALL_EPSILON)
{
w1 = w3 % csVector3 (0, 0, -1);
sqr = w1 * w1;
if (sqr < SMALL_EPSILON)
{
w1 = w3 % csVector3 (0, -1, 0);
sqr = w1 * w1;
}
}
w1 *= csQisqrt (sqr);
w2 = w3 % w1;
return true;
}
return false;
}
void PerspectiveImpl::ComputeDefaultAngle (float width)
{
float rview_fov = (float)GetDefaultFOV () * 0.5f;
float disp_width = (float)width * 0.5f;
float inv_disp_radius = csQisqrt (
rview_fov * rview_fov + disp_width * disp_width);
default_fov_angle = 2.0f * (float)acos (disp_width * inv_disp_radius)
* (360.0f / TWO_PI);
}
void csSprite2DMeshObject::CheckBeam (const csVector3& /*start*/,
const csVector3& pl, float sqr, csMatrix3& o2t)
{
// This method is an optimized version of LookAt() based on
// the presumption that the up vector is always (0,1,0).
// This is used to create a transform to move the intersection
// to the sprites vector space, then it is tested against the 2d
// coords, which are conveniently located at z=0.
// The transformation matrix is stored and used again if the
// start vector for the beam is in the same position. MHV.
csVector3 pl2 = pl * csQisqrt (sqr);
csVector3 v1( pl2.z, 0, -pl2.x);
sqr = v1*v1;
v1 *= csQisqrt(sqr);
csVector3 v2(pl2.y * v1.z, pl2.z * v1.x - pl2.x * v1.z, -pl2.y * v1.x);
o2t.Set (v1.x, v2.x, pl2.x,
v1.y, v2.y, pl2.y,
v1.z, v2.z, pl2.z);
}
