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authorAndré Nusser <andre.nusser@googlemail.com>2020-04-19 22:50:57 +0200
committerAndré Nusser <andre.nusser@googlemail.com>2020-04-19 22:50:57 +0200
commitfc8a6632d515fa36aa14e95bb1bbde57a10fd43a (patch)
tree2f5ece7b3addd9b00ad62eb3b02e65c424c4439c /src
parent4191e78012ad4cd5fc216aa355ee97a682065ce4 (diff)
Add untested version of Powermap with all features.
Diffstat (limited to 'src')
-rw-r--r--src/Makefile.am2
-rw-r--r--src/powermap.cc171
-rw-r--r--src/powermap.h35
3 files changed, 179 insertions, 29 deletions
diff --git a/src/Makefile.am b/src/Makefile.am
index a8e5c74..09df750 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -58,6 +58,7 @@ libdg_la_SOURCES = \
midimapper.cc \
path.cc \
powerlist.cc \
+ powermap.cc \
random.cc \
sample.cc \
sample_selection.cc \
@@ -113,6 +114,7 @@ EXTRA_DIST = \
path.h \
platform.h \
powerlist.h \
+ powermap.h \
random.h \
range.h \
rangemap.h \
diff --git a/src/powermap.cc b/src/powermap.cc
index 6a5bba0..00365af 100644
--- a/src/powermap.cc
+++ b/src/powermap.cc
@@ -26,41 +26,182 @@
*/
#include "powermap.h"
+#include <cassert>
#include <cmath>
-Power Powermap::map(Power in) const
+namespace
{
- if (in < fixed_map.in) {
- return a1*pow(in,3) + b1*pow(in,2) + c1*in + d1;
+
+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(
+ Power const x, PowerPair const& P0, PowerPair const& P1, Power const m0, Power const m1)
+{
+ auto const x0 = P0.in;
+ auto const x1 = P1.in;
+ auto const y0 = P0.out;
+ auto const y1 = P1.out;
+ auto const dx = x1 - x0;
+ auto const x_prime = (x - x1)/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)
+{
+ if (spline_needs_update) {
+ updateSpline();
}
- else {
- return a2*pow(in,3) + b2*pow(in,2) + c2*in + d2;
+
+ if (in < fixed[0].in) {
+ return shelf ? fixed[0].out : computeValue(in, {0.,0.}, fixed[0], m[0], m[1]);
+ }
+ else if (in < fixed[1].in) {
+ return computeValue(in, fixed[0], fixed[1], m[1], m[2]);
+ }
+ else if (in < fixed[2].in) {
+ return computeValue(in, fixed[1], fixed[2], m[2], m[3]);
+ }
+ else { // in >= fixed[2].in
+ return shelf ? fixed[2].out : computeValue(in, fixed[2], {1.,1.}, m[3], m[4]);
}
}
void Powermap::reset()
{
- min_input = 0.;
- max_input = 1.;
- fixed_map = {.5, .5};
+ fixed[0] = {0., 0.};
+ fixed[1] = {.5, .5};
+ fixed[2] = {1., 1.};
+ shelf = false;
+
+ updateSpline();
+}
+
+void Powermap::setFixed0(PowerPair new_value)
+{
+ if (fixed[0] != new_value) {
+ spline_needs_update = true;
+ this->fixed[0] = new_value;
+ }
}
-void Powermap::setMinInput(Power min_input)
+void Powermap::setFixed1(PowerPair new_value)
{
- this->min_input = min_input;
+ if (fixed[1] != new_value) {
+ spline_needs_update = true;
+ this->fixed[1] = new_value;
+ }
}
-void Powermap::setMaxInput(Power max_input)
+void Powermap::setFixed2(PowerPair new_value)
{
- this->max_input = max_input;
+ if (fixed[2] != new_value) {
+ spline_needs_update = true;
+ this->fixed[2] = new_value;
+ }
}
-void Powermap::setFixed(PowerPair fixed)
+void Powermap::setShelf(bool enable)
{
- this->fixed = fixed;
+ if (shelf != enable) {
+ spline_needs_update = true;
+ this->shelf = enable;
+ }
}
+// This mostly followes the wikipedia article for monotone cubic splines:
+// https://en.wikipedia.org/wiki/Monotone_cubic_interpolation
void Powermap::updateSpline()
{
- // TODO
+ 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 P = shelf ? Powers{fixed[0].out, fixed[1].out, fixed[2].out}
+ : Powers{0., fixed[0].out, fixed[1].out, fixed[2].out, 1.};
+
+ Powers deltas(X.size()-1);
+ Powers m(X.size());
+
+ // 1
+ for (std::size_t i = 0; i < deltas.size(); ++i) {
+ deltas[i] = (P[i+1]-P[i])/(X[i+1]-X[i]);
+ }
+
+ // 2
+ m[0] = deltas[0];
+ for (std::size_t i = 1; i < deltas.size(); ++i) {
+ m[i] = (deltas[i-1] + deltas[i])/2.;
+ }
+ m.back() = deltas.back();
+
+ // 3
+ std::vector<bool> ignore(deltas.size(), false);
+ for (std::size_t i = 0; i < deltas.size(); ++i) {
+ if (deltas[i] == 0) {
+ m[i] = 0;
+ m[i+1] = 0;
+ ignore[i] = true;
+ }
+ }
+
+ for (std::size_t i = 0; i < deltas.size(); ++i) {
+ if (ignore[i]) {
+ continue;
+ }
+
+ // 4
+ auto alpha = m[i]/deltas[i];
+ auto beta = m[i+1]/deltas[i];
+ assert(alpha >= 0.);
+ assert(beta >= 0.);
+
+ // 5
+ // TODO: expose this parameter for testing both
+ bool const option1 = true;
+ if (option1) {
+ if (alpha > 3 || beta > 3) {
+ m[i] = 3*deltas[i];
+ }
+ }
+ else {
+ auto const a2b2 = alpha*alpha + beta*beta;
+ if (a2b2 > 9) {
+ auto const tau = 3./sqrt(a2b2);
+ m[i] = tau*alpha*deltas[i];
+ m[i+1] = tau*alpha*deltas[i];
+ }
+ }
+ }
+
+ if (shelf) {
+ assert(m.size() == 3);
+ this->m[1] = m[0];
+ this->m[2] = m[1];
+ this->m[3] = m[2];
+ }
+ else {
+ assert(m.size() == 5);
+ for (std::size_t i = 0; i < m.size(); ++i) {
+ this->m[i] = m[i];
+ }
+ }
+
+ spline_needs_update = false;
}
diff --git a/src/powermap.h b/src/powermap.h
index 8dcccc9..589573f 100644
--- a/src/powermap.h
+++ b/src/powermap.h
@@ -26,34 +26,41 @@
*/
#pragma once
+#include <array>
+#include <vector>
+
class Powermap
{
+public:
using Power = float;
+ using Powers = std::vector<Power>;
struct PowerPair {
Power in;
Power out;
+
+ bool operator!=(PowerPair const& other) {
+ return in != other.in || out != other.out;
+ }
};
-public:
- Powermap() = default;
+ Powermap();
- Power map(Power in) const;
+ Power map(Power in);
void reset();
- // set parameters
- void setMinInput(Power min_input);
- void setMaxInput(Power max_input);
- void setFixed(PowerPair fixed);
+ void setFixed0(PowerPair new_value);
+ void setFixed1(PowerPair new_value);
+ void setFixed2(PowerPair new_value);
+ void setShelf(bool enable);
private:
- // input parameters
- Power min_input;
- Power max_input;
- PowerPair fixed;
+ // input parameters (state of this class)
+ std::array<PowerPair, 3> fixed;
+ bool shelf;
- // spline parameters
- float a1, b1, c1, d1;
- float a2, b2, c2, d2;
+ // spline parameters (deterministically computed from the input parameters)
+ std::array<float, 5> m;
+ bool spline_needs_update;
void updateSpline();
};