From e1658b7ffaae49085ea8ef501b24b8645b071b85 Mon Sep 17 00:00:00 2001
From: DaMichel <mw.pub@welter-4d.de>
Date: Thu, 4 Aug 2016 10:06:36 +0200
Subject: filter/kalman: log sliders that only change a single decimal digit at
 a time when moved

---
 filter-kalman/ftnoir_kalman_filtercontrols.ui | 24 +++++++++++++++---------
 filter-kalman/kalman.h                        | 27 ++++++++++++++++++++++++---
 2 files changed, 39 insertions(+), 12 deletions(-)

diff --git a/filter-kalman/ftnoir_kalman_filtercontrols.ui b/filter-kalman/ftnoir_kalman_filtercontrols.ui
index 2e9bcae7..6ec18ba8 100644
--- a/filter-kalman/ftnoir_kalman_filtercontrols.ui
+++ b/filter-kalman/ftnoir_kalman_filtercontrols.ui
@@ -9,7 +9,7 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>431</width>
+    <width>438</width>
     <height>141</height>
    </rect>
   </property>
@@ -52,11 +52,14 @@
       <item row="0" column="1">
        <widget class="QSlider" name="noiseRotSlider">
         <property name="maximum">
-         <number>10000</number>
+         <number>400</number>
         </property>
         <property name="singleStep">
          <number>1</number>
         </property>
+        <property name="pageStep">
+         <number>100</number>
+        </property>
         <property name="tracking">
          <bool>true</bool>
         </property>
@@ -67,10 +70,10 @@
          <bool>false</bool>
         </property>
         <property name="tickPosition">
-         <enum>QSlider::NoTicks</enum>
+         <enum>QSlider::TicksBelow</enum>
         </property>
         <property name="tickInterval">
-         <number>10</number>
+         <number>100</number>
         </property>
        </widget>
       </item>
@@ -84,16 +87,19 @@
       <item row="1" column="1">
        <widget class="QSlider" name="noisePosSlider">
         <property name="maximum">
-         <number>10000</number>
+         <number>400</number>
+        </property>
+        <property name="pageStep">
+         <number>100</number>
         </property>
         <property name="orientation">
          <enum>Qt::Horizontal</enum>
         </property>
         <property name="tickPosition">
-         <enum>QSlider::NoTicks</enum>
+         <enum>QSlider::TicksBelow</enum>
         </property>
         <property name="tickInterval">
-         <number>10</number>
+         <number>100</number>
         </property>
        </widget>
       </item>
@@ -101,7 +107,7 @@
        <widget class="QLabel" name="noiseRotLabel">
         <property name="minimumSize">
          <size>
-          <width>60</width>
+          <width>65</width>
           <height>0</height>
          </size>
         </property>
@@ -114,7 +120,7 @@
        <widget class="QLabel" name="noisePosLabel">
         <property name="minimumSize">
          <size>
-          <width>60</width>
+          <width>65</width>
           <height>0</height>
          </size>
         </property>
diff --git a/filter-kalman/kalman.h b/filter-kalman/kalman.h
index 3bb5aad2..3c9466a5 100644
--- a/filter-kalman/kalman.h
+++ b/filter-kalman/kalman.h
@@ -96,10 +96,31 @@ struct settings : opts {
     static constexpr double process_sigma_pos = 0.5;
     static constexpr double process_simga_rot = 0.5;
 
-    static double map_slider_value(const slider_value &v)
+    static double map_slider_value(const slider_value &v_)
     {
-        //return std::pow(4., v * 5. - 4.) / 4. * 10.; // not so much difference, except that it is harder to adjust the min-max range.
-        return std::pow(10., v * 4. - 3.);
+        const double v = v_;
+#if 0
+        //return std::pow(10., v * 4. - 3.);
+#else
+        constexpr int min_log10 = -3;
+        constexpr int max_log10 = 1;
+        constexpr int num_divisions = max_log10 - min_log10;
+        /* ascii art representation of slider
+          // ----- //  ------//  ------// ------- //   4 divisions
+         -3    -   2         -1        0           1    power of 10
+                   |      |
+                   |      f + left_side_log10
+                   |
+                   left_side_log10
+        */
+        const int k = v * num_divisions; // in which division are we?!
+        const double f = v * num_divisions - k; // where in the division are we?!
+        const double ff = f * 9. + 1.;
+        const double multiplier = int(ff * 10.) / 10.;
+        const int left_side_log10 = min_log10 + k;
+        const double val = std::pow(10., left_side_log10) * multiplier;
+        return val;
+#endif
     }
 
     settings() :
-- 
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