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authorTavian Barnes <tavianator@gmail.com>2011-06-14 08:37:55 -0600
committerTavian Barnes <tavianator@gmail.com>2011-06-14 08:37:55 -0600
commit9ed4a01ac4305baff9e5ee1484691e78def105a1 (patch)
treea8b5c556baf7053546e188e42278c6b88c7b0543 /libdimension
parent9b758508df283a533a4cfc605545a35f77bc9d5f (diff)
downloaddimension-9ed4a01ac4305baff9e5ee1484691e78def105a1.tar.xz
Fix rotational alignment.
Diffstat (limited to 'libdimension')
-rw-r--r--libdimension/dimension/geometry.h14
-rw-r--r--libdimension/geometry.c39
-rw-r--r--libdimension/libdimension.pc.in2
3 files changed, 40 insertions, 15 deletions
diff --git a/libdimension/dimension/geometry.h b/libdimension/dimension/geometry.h
index ba8f531..7e466dd 100644
--- a/libdimension/dimension/geometry.h
+++ b/libdimension/dimension/geometry.h
@@ -178,6 +178,16 @@ dmnsn_matrix dmnsn_translation_matrix(dmnsn_vector d);
* @return The transformation matrix.
*/
dmnsn_matrix dmnsn_rotation_matrix(dmnsn_vector theta);
+/**
+ * An alignment matrix.
+ * @param[in] from The initial vector.
+ * @param[in] to The desired direction.
+ * @param[in] axis1 The first axis about which to rotate.
+ * @param[in] axis2 The second axis about which to rotate.
+ * @return A transformation matrix that will rotate \p from to \p to.
+ */
+dmnsn_matrix dmnsn_alignment_matrix(dmnsn_vector from, dmnsn_vector to,
+ dmnsn_vector axis1, dmnsn_vector axis2);
/**
* Construct a new line.
@@ -359,10 +369,6 @@ dmnsn_vector_max(dmnsn_vector a, dmnsn_vector b)
);
}
-/** Return the angle between two vectors with respect to an axis. */
-double dmnsn_vector_axis_angle(dmnsn_vector v1, dmnsn_vector v2,
- dmnsn_vector axis);
-
/** Invert a matrix. */
dmnsn_matrix dmnsn_matrix_inverse(dmnsn_matrix A);
diff --git a/libdimension/geometry.c b/libdimension/geometry.c
index b36b9c3..f7c6842 100644
--- a/libdimension/geometry.c
+++ b/libdimension/geometry.c
@@ -82,27 +82,46 @@ dmnsn_rotation_matrix(dmnsn_vector theta)
}
/* Find the angle between two vectors with respect to an axis */
-double
-dmnsn_vector_axis_angle(dmnsn_vector v1, dmnsn_vector v2, dmnsn_vector axis)
+static double
+dmnsn_axis_angle(dmnsn_vector from, dmnsn_vector to, dmnsn_vector axis)
{
- dmnsn_vector d = dmnsn_vector_sub(v1, v2);
- dmnsn_vector proj = dmnsn_vector_add(dmnsn_vector_proj(d, axis), v2);
+ from = dmnsn_vector_sub(from, dmnsn_vector_proj(from, axis));
+ to = dmnsn_vector_sub(to, dmnsn_vector_proj(to, axis));
- double projn = dmnsn_vector_norm(proj);
- if (fabs(projn) < dmnsn_epsilon)
+ double fromnorm = dmnsn_vector_norm(from);
+ double tonorm = dmnsn_vector_norm(to);
+ if (fromnorm < dmnsn_epsilon || tonorm < dmnsn_epsilon) {
return 0.0;
+ }
+
+ from = dmnsn_vector_div(from, fromnorm);
+ to = dmnsn_vector_div(to, tonorm);
- double c = dmnsn_vector_dot(dmnsn_vector_normalized(v1),
- dmnsn_vector_div(proj, projn));
- double angle = acos(c);
+ double angle = acos(dmnsn_vector_dot(from, to));
- if (dmnsn_vector_dot(dmnsn_vector_cross(v1, proj), axis) > 0.0) {
+ if (dmnsn_vector_dot(dmnsn_vector_cross(from, to), axis) > 0.0) {
return angle;
} else {
return -angle;
}
}
+/* Alignment matrix */
+dmnsn_matrix
+dmnsn_alignment_matrix(dmnsn_vector from, dmnsn_vector to,
+ dmnsn_vector axis1, dmnsn_vector axis2)
+{
+ double theta1 = dmnsn_axis_angle(from, to, axis1);
+ dmnsn_matrix align1 = dmnsn_rotation_matrix(dmnsn_vector_mul(theta1, axis1));
+ from = dmnsn_transform_vector(align1, from);
+ axis2 = dmnsn_transform_vector(align1, axis2);
+
+ double theta2 = dmnsn_axis_angle(from, to, axis2);
+ dmnsn_matrix align2 = dmnsn_rotation_matrix(dmnsn_vector_mul(theta2, axis2));
+
+ return dmnsn_matrix_mul(align2, align1);
+}
+
/* Matrix inversion helper functions */
/** A 2x2 matrix for inversion by partitioning. */
diff --git a/libdimension/libdimension.pc.in b/libdimension/libdimension.pc.in
index 97a3cb5..fd5649f 100644
--- a/libdimension/libdimension.pc.in
+++ b/libdimension/libdimension.pc.in
@@ -6,6 +6,6 @@ includedir=@includedir@
Name: libdimension
Description: The Dimension Library
Requires:
-Version: @VERSION@
+Version: @PACKAGE_VERSION@
Libs: -L${libdir} -ldimension
Cflags: