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Add a shortcut function for quaterion/vector multiplication.

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I got the idea from blender when I discovered by accident that quat * vect
produces the same result as quat * qvect * quat* and looked up the code to
check what was going on. While matrix/vector multiplication still beats the
pants off quaternion/vector multiplication, QuatMultVec is a slight
optimization over quat * qvect * quat* (17+,24* vs 24+,32*, plus no need to
to generate quat*).
This commit is contained in:
Bill Currie 2012-04-26 09:24:05 +09:00
parent 7b0d48313d
commit efaef89c5f
3 changed files with 66 additions and 0 deletions
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1
include/QF/mathlib.h
View file

@ -413,6 +413,7 @@ void RotatePointAroundVector (vec3_t dst, const vec3_t axis,
const vec3_t point, float degrees);
void QuatMult (const quat_t q1, const quat_t q2, quat_t out);
void QuatMultVec (const quat_t q, const vec3_t v, vec3_t out);
void QuatInverse (const quat_t in, quat_t out);
void QuatExp (const quat_t a, quat_t b);
void QuatToMatrix (const quat_t q, vec_t *m, int homogenous, int vertical);

14
libs/util/mathlib.c
View file

@ -181,6 +181,20 @@ QuatMult (const quat_t q1, const quat_t q2, quat_t out)
out[0] = s;
}
VISIBLE void
QuatMultVec (const quat_t q, const vec3_t v, vec3_t out)
{
vec_t s;
vec3_t tv;
s = -DotProduct (q + 1, v);
CrossProduct (q + 1, v, tv);
VectorMultAdd (tv, q[0], v, tv);
CrossProduct (q + 1, tv, out);
VectorMultSub (out, s, q + 1, out);
VectorMultAdd (out, q[0], tv, out);
}
VISIBLE void
QuatInverse (const quat_t in, quat_t out)
{

51
libs/util/test/test-quat.c
View file

@ -82,6 +82,52 @@ fail:
return 0;
}
static int
test_rotation2 (const vec3_t angles)
{
int i;
vec3_t forward, right, up;
quat_t quat;
vec3_t f, r, u;
vec3_t vf = {1, 0, 0};
vec3_t vr = {0, -1, 0};
vec3_t vu = {0, 0, 1};
AngleVectors (angles, forward, right, up);
AngleQuat (angles, quat);
// rotate forward vector
QuatMultVec (quat, vf, f);
// rotate right vector
QuatMultVec (quat, vr, r);
// rotate up vector
QuatMultVec (quat, vu, u);
for (i = 0; i < 3; i++)
if (!compare (forward[i], f[i]))
goto fail;
for (i = 0; i < 3; i++)
if (!compare (right[i], r[i]))
goto fail;
for (i = 0; i < 3; i++)
if (!compare (up[i], u[i]))
goto fail;
return 1;
fail:
printf ("\n\n%g %g %g\n\n", angles[0], angles[1], angles[2]);
printf ("%g %g %g\n", forward[0], forward[1], forward[2]);
printf ("%g %g %g\n", right[0], right[1], right[2]);
printf ("%g %g %g\n\n", up[0], up[1], up[2]);
printf ("%g %g %g\n", f[0], f[1], f[2]);
printf ("%g %g %g\n", r[0], r[1], r[2]);
printf ("%g %g %g\n", u[0], u[1], u[2]);
return 0;
}
int
main (int argc, const char **argv)
{
@ -92,5 +138,10 @@ main (int argc, const char **argv)
if (!test_rotation (test_angles[i]))
res = 1;
}
for (i = 0; i < num_angle_tests; i ++) {
if (!test_rotation2 (test_angles[i]))
res = 1;
}
return res;
}