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Diffstat (limited to 'src/powermap.cc')
| -rw-r--r-- | src/powermap.cc | 251 |
1 files changed, 0 insertions, 251 deletions
diff --git a/src/powermap.cc b/src/powermap.cc deleted file mode 100644 index 2bb45b7..0000000 --- a/src/powermap.cc +++ /dev/null @@ -1,251 +0,0 @@ -/* -*- Mode: c++ -*- */ -/*************************************************************************** - * powermap.cc - * - * Fri Apr 17 23:06:12 CEST 2020 - * Copyright 2020 André Nusser - * andre.nusser@googlemail.com - ****************************************************************************/ - -/* - * This file is part of DrumGizmo. - * - * DrumGizmo is free software; you can redistribute it and/or modify - * it under the terms of the GNU Lesser General Public License as published by - * the Free Software Foundation; either version 3 of the License, or - * (at your option) any later version. - * - * DrumGizmo is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU Lesser General Public License for more details. - * - * You should have received a copy of the GNU Lesser General Public License - * along with DrumGizmo; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. - */ -#include "powermap.h" - -#include <cassert> -#include <cmath> - -namespace -{ - -using Power = Powermap::Power; -using PowerPair = Powermap::PowerPair; - -Power h00(Power x) -{ - return (1 + 2 * x) * pow(1 - x, 2); -} - -Power h10(Power x) -{ - return x * pow(1 - x, 2); -} - -Power h01(Power x) -{ - return x * x * (3 - 2 * x); -} - -Power h11(Power x) -{ - return x * x * (x - 1); -} - -Power computeValue(const Power x, const PowerPair& P0, const PowerPair& P1, - const Power m0, const Power m1) -{ - const auto x0 = P0.in; - const auto x1 = P1.in; - const auto y0 = P0.out; - const auto y1 = P1.out; - const auto dx = x1 - x0; - const auto x_prime = (x - x0)/dx; - - return - h00(x_prime) * y0 + - h10(x_prime) * dx * m0 + - h01(x_prime) * y1 + - h11(x_prime) * dx * m1; -} - -} // end anonymous namespace - -Powermap::Powermap() -{ - reset(); -} - -Power Powermap::map(Power in) -{ - assert(in >= 0. && in <= 1.); - - if (spline_needs_update) - { - updateSpline(); - } - - Power out; - if (in < fixed[0].in) - { - out = shelf ? fixed[0].out - : computeValue(in, {0.,0.}, fixed[0], m[0], m[1]); - } - else if (in < fixed[1].in) - { - out = computeValue(in, fixed[0], fixed[1], m[1], m[2]); - } - else if (in < fixed[2].in) - { - out = computeValue(in, fixed[1], fixed[2], m[2], m[3]); - } - else - { - // in >= fixed[2].in - out = shelf ? fixed[2].out - : computeValue(in, fixed[2], {1.,1.}, m[3], m[4]); - } - - assert(out >= 0. && out <= 1.); - return out; -} - -void Powermap::reset() -{ - setFixed0({eps, eps}); - setFixed1({.5, .5}); - setFixed2({1 - eps, 1 - eps}); - // FIXME: better false? - shelf = true; - - updateSpline(); -} - -void Powermap::setFixed0(PowerPair new_value) -{ - if (fixed[0] != new_value) - { - spline_needs_update = true; - fixed[0].in = clamp(new_value.in, eps, fixed[1].in - eps); - fixed[0].out = clamp(new_value.out, eps, fixed[1].out - eps); - } -} - -void Powermap::setFixed1(PowerPair new_value) -{ - if (fixed[1] != new_value) - { - spline_needs_update = true; - fixed[1].in = clamp(new_value.in, fixed[0].in + eps, fixed[2].in - eps); - fixed[1].out = clamp(new_value.out, fixed[0].out + eps, fixed[2].out - eps); - } -} - -void Powermap::setFixed2(PowerPair new_value) -{ - if (fixed[2] != new_value) - { - spline_needs_update = true; - fixed[2].in = clamp(new_value.in, fixed[1].in + eps, 1 - eps); - fixed[2].out = clamp(new_value.out, fixed[1].out + eps, 1 - eps); - } -} - -void Powermap::setShelf(bool enable) -{ - if (shelf != enable) - { - spline_needs_update = true; - this->shelf = enable; - } -} - -PowerPair Powermap::getFixed0() const -{ - return fixed[0]; -} - -PowerPair Powermap::getFixed1() const -{ - return fixed[1]; -} - -PowerPair Powermap::getFixed2() const -{ - return fixed[2]; -} - -// This mostly followes the wikipedia article for monotone cubic splines: -// https://en.wikipedia.org/wiki/Monotone_cubic_interpolation -void Powermap::updateSpline() -{ - assert(0. <= fixed[0].in && fixed[0].in < fixed[1].in && - fixed[1].in < fixed[2].in && fixed[2].in <= 1.); - assert(0. <= fixed[0].out && fixed[0].out <= fixed[1].out && - fixed[1].out <= fixed[2].out && fixed[2].out <= 1.); - - Powers X = shelf ? Powers{fixed[0].in, fixed[1].in, fixed[2].in} - : Powers{0., fixed[0].in, fixed[1].in, fixed[2].in, 1.}; - Powers Y = shelf ? Powers{fixed[0].out, fixed[1].out, fixed[2].out} - : Powers{0., fixed[0].out, fixed[1].out, fixed[2].out, 1.}; - - auto slopes = calcSlopes(X, Y); - - if (shelf) - { - assert(slopes.size() == 3); - this->m[1] = slopes[0]; - this->m[2] = slopes[1]; - this->m[3] = slopes[2]; - } - else - { - assert(slopes.size() == 5); - for (std::size_t i = 0; i < m.size(); ++i) - { - this->m[i] = slopes[i]; - } - } - - spline_needs_update = false; -} - -// This follows the monotone cubic spline algorithm of Steffen, from: -// "A Simple Method for Monotonic Interpolation in One Dimension" -std::vector<float> Powermap::calcSlopes(const Powers& X, const Powers& Y) -{ - Powers m(X.size()); - - Powers d(X.size() - 1); - Powers h(X.size() - 1); - for (std::size_t i = 0; i < d.size(); ++i) - { - h[i] = X[i + 1] - X[i]; - d[i] = (Y[i + 1] - Y[i]) / h[i]; - } - - m.front() = d.front(); - for (std::size_t i = 1; i < m.size() - 1; ++i) - { - m[i] = (d[i - 1] + d[i]) / 2.; - } - m.back() = d.back(); - - for (std::size_t i = 1; i < m.size() - 1; ++i) - { - const auto min_d = 2*std::min(d[i - 1], d[i]); - m[i] = - std::min<float>(min_d, - (h[i] * d[i - 1] + h[i - 1] * d[i]) / (h[i - 1] + h[i])); - } - - return m; -} - -Power Powermap::clamp(Power in, Power min, Power max) const -{ - return std::max(min, std::min(in, max)); -} |