diff options
Diffstat (limited to '')
| -rw-r--r-- | src/transf_mat_3x4.cpp | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/src/transf_mat_3x4.cpp b/src/transf_mat_3x4.cpp new file mode 100644 index 0000000..391783b --- /dev/null +++ b/src/transf_mat_3x4.cpp @@ -0,0 +1,190 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * 3x4 transformation matrix to map points from projective 3-space into the projective plane + * + * Authors: + * Maximilian Albert <Anhalter42@gmx.de> + * + * Copyright (C) 2007 Authors + * + * Released under GNU GPL v2+, read the file 'COPYING' for more information. + */ + +#include "transf_mat_3x4.h" +#include <2geom/affine.h> +#include "svg/stringstream.h" +#include "syseq.h" + +namespace Proj { + +TransfMat3x4::TransfMat3x4 () { + for (unsigned int i = 0; i < 3; ++i) { + for (unsigned int j = 0; j < 4; ++j) { + tmat[i][j] = (i == j ? 1 : 0); // or should we initialize all values with 0? does it matter at all? + } + } +} + +TransfMat3x4::TransfMat3x4 (Proj::Pt2 vp_x, Proj::Pt2 vp_y, Proj::Pt2 vp_z, Proj::Pt2 origin) { + for (unsigned int i = 0; i < 3; ++i) { + tmat[i][0] = vp_x[i]; + tmat[i][1] = vp_y[i]; + tmat[i][2] = vp_z[i]; + tmat[i][3] = origin[i]; + } +} + +TransfMat3x4::TransfMat3x4(TransfMat3x4 const &rhs) { + for (unsigned int i = 0; i < 3; ++i) { + for (unsigned int j = 0; j < 4; ++j) { + tmat[i][j] = rhs.tmat[i][j]; + } + } +} + +Pt2 +TransfMat3x4::column (Proj::Axis axis) const { + return Proj::Pt2 (tmat[0][axis], tmat[1][axis], tmat[2][axis]); +} + +Pt2 +TransfMat3x4::image (Pt3 const &point) { + double x = tmat[0][0] * point[0] + tmat[0][1] * point[1] + tmat[0][2] * point[2] + tmat[0][3] * point[3]; + double y = tmat[1][0] * point[0] + tmat[1][1] * point[1] + tmat[1][2] * point[2] + tmat[1][3] * point[3]; + double w = tmat[2][0] * point[0] + tmat[2][1] * point[1] + tmat[2][2] * point[2] + tmat[2][3] * point[3]; + + return Pt2 (x, y, w); +} + +Pt3 +TransfMat3x4::preimage (Geom::Point const &pt, double coord, Proj::Axis axis) { + const double init_val = std::numeric_limits<double>::quiet_NaN(); + double x[4] = { init_val, init_val, init_val, init_val }; + double v[3] = { pt[Geom::X], pt[Geom::Y], 1.0 }; + int index = (int) axis; + + SysEq::SolutionKind sol = SysEq::gaussjord_solve<3,4>(tmat, x, v, index, coord, true); + + if (sol != SysEq::unique) { + if (sol == SysEq::no_solution) { + g_print ("No solution. Please investigate.\n"); + } else { + g_print ("Infinitely many solutions. Please investigate.\n"); + } + } + return Pt3(x[0], x[1], x[2], x[3]); +} + +void +TransfMat3x4::set_image_pt (Proj::Axis axis, Proj::Pt2 const &pt) { + // FIXME: Do we need to adapt the coordinates in any way or can we just use them as they are? + for (int i = 0; i < 3; ++i) { + tmat[i][axis] = pt[i]; + } +} + +void +TransfMat3x4::toggle_finite (Proj::Axis axis) { + g_return_if_fail (axis != Proj::W); + if (has_finite_image(axis)) { + Geom::Point dir (column(axis).affine()); + Geom::Point origin (column(Proj::W).affine()); + dir -= origin; + set_column (axis, Proj::Pt2(dir[Geom::X], dir[Geom::Y], 0)); + } else { + Proj::Pt2 dir (column(axis)); + Proj::Pt2 origin (column(Proj::W).affine()); + dir = dir + origin; + dir[2] = 1.0; + set_column (axis, dir); + } +} + +gchar * +TransfMat3x4::pt_to_str (Proj::Axis axis) { + Inkscape::SVGOStringStream os; + os << tmat[0][axis] << " : " + << tmat[1][axis] << " : " + << tmat[2][axis]; + return g_strdup(os.str().c_str()); +} + +/* Check for equality (with a small tolerance epsilon) */ +bool +TransfMat3x4::operator==(const TransfMat3x4 &rhs) const +{ + // Should we allow a certain tolerance or "normalize" the matrices first? + for (int i = 0; i < 3; ++i) { + Proj::Pt2 pt1 = column(Proj::axes[i]); + Proj::Pt2 pt2 = rhs.column(Proj::axes[i]); + if (pt1 != pt2) { + return false; + } + } + return true; +} + +/* Multiply a projective matrix by an affine matrix (by only multiplying the 'affine part' of the + * projective matrix) */ +TransfMat3x4 +TransfMat3x4::operator*(Geom::Affine const &A) const { + TransfMat3x4 ret; + + for (int j = 0; j < 4; ++j) { + ret.tmat[0][j] = A[0]*tmat[0][j] + A[2]*tmat[1][j] + A[4]*tmat[2][j]; + ret.tmat[1][j] = A[1]*tmat[0][j] + A[3]*tmat[1][j] + A[5]*tmat[2][j]; + ret.tmat[2][j] = tmat[2][j]; + } + + return ret; +} + +// FIXME: Shouldn't rather operator* call operator*= for efficiency? (Because in operator*= +// there is in principle no need to create a temporary object, which happens in the assignment) +TransfMat3x4 & +TransfMat3x4::operator*=(Geom::Affine const &A) { + *this = *this * A; + return *this; +} + +void +TransfMat3x4::copy_tmat(double rhs[3][4]) { + for (int i = 0; i < 3; ++i) { + for (int j = 0; j < 4; ++j) { + rhs[i][j] = tmat[i][j]; + } + } +} + +void +TransfMat3x4::print () const { + g_print ("Transformation matrix:\n"); + for (const auto & i : tmat) { + g_print (" "); + for (double j : i) { + g_print ("%8.2f ", j); + } + g_print ("\n"); + } +} + +void +TransfMat3x4::normalize_column (Proj::Axis axis) { + Proj::Pt2 new_col(column(axis)); + new_col.normalize(); + set_image_pt(axis, new_col); +} + + +} // namespace Proj + +/* + Local Variables: + mode:c++ + c-file-style:"stroustrup" + c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +)) + indent-tabs-mode:nil + fill-column:99 + End: +*/ +// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 : |