feat: Add log axes (#18)

* feat: Add log axes

* Remove dead file

* Fix c++ formatting

src/CMakeLists.txt

@@ -11,10 +11,13 @@ qt_add_qml_module(
   axisTickLabels.cpp
   lineGeometry.cpp
   lineGeometry.h
+  logAxis.h
+  logAxis.cpp
   scatterGeometry.cpp
   scatterGeometry.h
   QML_FILES
   main.qml
+  AxisModel.qml
   LineModel.qml
   ScatterModel.qml)
 

src/axis.cpp

@@ -82,7 +82,7 @@ void Axis::updateData()
     update();
 }
 
-std::vector<float> Axis::convert(QList<double> points)
+std::vector<float> Axis::convert(QList<double> points) const
 {
     std::vector<float> result(points.length());
 
@@ -91,3 +91,8 @@ std::vector<float> Axis::convert(QList<double> points)
 
     return result;
 }
+
+double Axis::tick(int index, int count) const
+{
+    return minimum_ + (double)index / ((double)count - 1.0) * (maximum_ - minimum_);
+}

src/axis.h

@@ -17,13 +17,14 @@ class Axis : public QQuick3DGeometry
 
     public:
     Axis();
-    std::vector<float> convert(QList<double> values);
+    virtual std::vector<float> convert(QList<double> values) const;
     AxisTickLabels *tickLabels();
     bool direction() const;
     double minimum() const;
     double maximum() const;
     int tickCount() const;
     void setTickCount(const int count);
+    virtual double tick(int index, int count) const;
 
     Q_SIGNALS:
     void dataChanged();

src/axisTickLabels.cpp

@@ -20,8 +20,7 @@ QVariant AxisTickLabels::data(const QModelIndex &index, int role) const
     switch (role)
     {
         case Qt::UserRole:
-            return QString("%1").arg(parent_.minimum() +
-                                     index.row() / ((double)N_ - 1) * (parent_.maximum() - parent_.minimum()));
+            return QString("%1").arg(parent_.tick(index.row(), N_));
         case (Qt::UserRole + 1):
             return parent_.direction() ? index.row() : 0;
         case (Qt::UserRole + 2):

src/logAxis.cpp

@@ -0,0 +1,28 @@
+#include "logAxis.h"
+#include <algorithm>
+
+#include <cmath>
+#include <iostream>
+
+LogAxis::LogAxis() : Axis() {}
+
+std::vector<float> LogAxis::convert(QList<double> points) const
+{
+    std::vector<float> result(points.length());
+
+    auto min = log(minimum());
+    auto max = log(maximum());
+
+    std::transform(points.begin(), points.end(), result.begin(),
+                   [min, max](const auto x) { return -1.0f + 2 * (log(x) - min) / (max - min); });
+
+    return result;
+}
+
+double LogAxis::tick(int index, int count) const
+{
+    auto min = log(minimum());
+    auto max = log(maximum());
+
+    return exp(min + (double)index / ((double)count - 1.0) * (max - min));
+}

src/logAxis.h

@@ -0,0 +1,20 @@
+#pragma once
+
+#include "axis.h"
+#include "axisTickLabels.h"
+#include <QQuick3DGeometry>
+#include <QVector3D>
+
+class LogAxis : public Axis
+{
+    Q_OBJECT
+    QML_NAMED_ELEMENT(LogAxis)
+
+    public:
+    LogAxis();
+    std::vector<float> convert(QList<double> values) const override;
+    double tick(int index, int count) const override;
+
+    Q_SIGNALS:
+    void dataChanged();
+};

src/main.qml

@@ -49,7 +49,7 @@ ApplicationWindow {
             axis: Axis {
                 id: xAxis
 
-                direction: false
+                direction: true
                 maximum: 1.0
                 minimum: -1.0
                 thickness: 0.01
@@ -60,13 +60,14 @@ ApplicationWindow {
             color: "black"
             scl: root.scale
 
-            axis: Axis {
+            axis: LogAxis {
                 id: yAxis
 
-                direction: true
+                direction: false
                 maximum: 1.0
-                minimum: -1.0
+                minimum: 0.01
                 thickness: 0.01
+                tickCount: ticCount.value
             }
         }
     }