commit 153a9f0d8347e12d6987b0c38f68dc85e4ae1131
Author: Fisch <interfisch@gmx.net>
Date:   Sun Apr 8 18:20:11 2018 +0200

    inital commit, working roller coaster based ony physics

diff --git a/achterbahn.ino b/achterbahn.ino
new file mode 100644
index 0000000..cd18e9c
--- /dev/null
+++ b/achterbahn.ino
@@ -0,0 +1,161 @@
+#include <Adafruit_NeoPixel.h>
+#ifdef __AVR__
+  #include <avr/power.h>
+#endif
+
+#include <vector>
+#include "wagon.h"
+
+#define PIN D2
+#define NUMPIXELS 300
+
+Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);
+
+long lastPixelUpdate=0;
+#define PIXELUPDATETIME 10
+long lastRoutineUpdate=0;
+#define ROUTINEUPDATETIME 10
+
+long loopmillis=0;
+
+uint8_t height[NUMPIXELS];
+
+std::vector <Wagon> wagon_arr;
+uint8_t maxid=0;
+
+
+void setup() {
+  Serial.begin(115200);
+
+  for (int i=0;i<NUMPIXELS;i++){
+    height[i]=0;
+  }
+  //Temporaer
+  int h=0;
+  for (int i=2;i<=30;i++){
+    height[i]=h*43/(30-2);
+    h++;
+  }
+  for (int i=31;i<(31+55);i++){ //gerade obene ebene
+    height[i]=43;
+  }
+  h=30;
+  for (int i=(31+55);i<(31+55+30);i++){
+    height[i]=h*43/(30);
+    h--;
+  }
+
+  h=0;
+  for (int i=(31+55+30+40);i<=(31+55+30+40+15);i++){
+    height[i]=h*23/(15);
+    h++;
+  }
+  for (int i=(31+55+30+40+15);i<=(31+55+30+40+15+55);i++){ //gerade mittlere ebene
+    height[i]=23;
+  }
+  
+  h=20;
+  for (int i=(31+55+30+40+15+55);i<=(31+55+30+40+15+55+20);i++){ //gerade mittlere ebene
+    height[i]=h*23/20;
+    h--;
+  }
+
+
+  h=0;
+  for (int i=NUMPIXELS-30;i<NUMPIXELS;i++){
+    height[i]=h*40/30;
+    h++;
+  }
+  
+  
+
+  strip.begin();
+  strip.setBrightness(150);
+  strip.show(); // Initialize all pixels to 'off'
+  Serial.println("Started");
+
+  previewHeightmap();
+
+  spawnWagon();
+
+}
+
+void previewHeightmap(){
+  int maxheight=45;
+  for (int i=0;i<NUMPIXELS;i++){
+    
+    //uint32_t c=Wheel(height[i]*255/45);
+    uint8_t b=height[i]*255/45;
+    uint32_t c=strip.Color(255-b,b,0);
+    strip.setPixelColor(i,c);
+  }
+  strip.show();
+  delay(3000);
+}
+
+void spawnWagon(){
+  Wagon tmpr = Wagon(maxid++,NUMPIXELS,&strip, height, 35, 6, 0.5,0); //spawn new wagon
+  wagon_arr.push_back(tmpr);
+  Serial.println("Spawned Wagon");
+}
+
+void loop() {
+  loopmillis=millis();
+
+  //######################### Update LED Output
+  if (lastPixelUpdate+PIXELUPDATETIME<loopmillis){ 
+    lastPixelUpdate=loopmillis;
+
+    for (int i=0;i<NUMPIXELS;i++){ //all black
+      uint32_t c=strip.Color(0,0,0);
+      strip.setPixelColor(i,c);
+    }
+
+    for (std::vector<Wagon>::iterator it = wagon_arr.begin(); it != wagon_arr.end(); ++it) //all wagons
+    {
+      Wagon & w = *it;
+      w.updateGraphics();
+    }
+
+    strip.show();
+  }
+
+
+  if (lastRoutineUpdate+ROUTINEUPDATETIME<loopmillis-ROUTINEUPDATETIME){
+    Serial.println("Behind!!!!!!!!!!");
+  }
+  //######################### Update Physics
+  if (lastRoutineUpdate+ROUTINEUPDATETIME<loopmillis){
+    lastRoutineUpdate=loopmillis;
+
+    for (std::vector<Wagon>::iterator it = wagon_arr.begin(); it != wagon_arr.end(); ++it) //all wagons
+    {
+      Wagon & w = *it;
+      w.updatePhysics(ROUTINEUPDATETIME);
+      if (!w.alive())
+      {
+        it = wagon_arr.erase(it); // After erasing, it is now pointing the next element.
+        --it;
+        spawnWagon(); //spawn new one
+      }
+    }
+  }
+
+  
+  
+}
+
+// Input a value 0 to 255 to get a color value.
+// The colours are a transition r - g - b - back to r.
+uint32_t Wheel(byte WheelPos) {
+  WheelPos = 255 - WheelPos;
+  if(WheelPos < 85) {
+    return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
+  }
+  if(WheelPos < 170) {
+    WheelPos -= 85;
+    return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
+  }
+  WheelPos -= 170;
+  return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
+}
diff --git a/wagon.cpp b/wagon.cpp
new file mode 100644
index 0000000..bdf2587
--- /dev/null
+++ b/wagon.cpp
@@ -0,0 +1,134 @@
+#include "wagon.h"
+
+
+
+Wagon::Wagon(int id,int numpixels, Adafruit_NeoPixel *strip,uint8_t *height,float pos, float wagonlength,float startvel,float startacc)
+{
+  _id = id;
+  _numpixels=numpixels;
+  _pos = pos;
+  _wagonlength = wagonlength;
+  _strip=strip;
+  _height=height;
+  _vel=startvel;
+  _acc=startacc;
+
+}
+
+bool Wagon::operator==(const Wagon &r) const {
+  return (r._id == _id);
+}
+
+void Wagon::updatePhysics(float updatedelayms)
+{
+  
+  /*
+  float acceleration=0;
+  for (int cpos=int(_pos);cpos>int(_pos-_wagonlength);cpos--){
+    acceleration=(_height[(int)cpos]-_height[(int)cpos+1])*0.03;
+  }
+  acceleration/=int(_wagonlength);
+  _vel+= acceleration; //Acceleration from height difference
+  _vel*=1-0.001; //resistance
+  float airresistance=_vel*_vel *0.005;//air resistance
+  if (_vel>=0){
+    _vel-=airresistance;
+  }else{
+    _vel+=airresistance;
+  }*/
+  #define CONST_G 9.81
+  #define PIXELDISTANCE 1.6666667 // 1/60.0 * 100 
+  #define C_ROLL 0.001 // = Croll * G    https://de.wikipedia.org/wiki/Rollwiderstand   0.001
+  #define AIRRES 0.18 //C_w*A*0.5*rho     Air resistance:  C_w * A * 0.5 * rho  (.... *v^2)
+  //http://www.kfz-tech.de/Biblio/Formelsammlung/Luftwiderstand.htm   C_w 0.6 
+  //rho  Massendichte luft  1,2041
+  //A = 1m^2
+
+  float m=50/_wagonlength; //mass of part of a wagon
+
+
+  _acc=0;
+  int cpos=(int)_pos;
+  for (int cpos=(int)_pos;cpos>(int)(_pos-_wagonlength);cpos--){ //for each wagon
+
+    float hdiff=getHeight((int) (cpos-0.5)) - getHeight((int)(cpos+0.5));
+
+    //Serial.print("hdiff=");
+    //Serial.print(hdiff);
+  
+    float beta=atan2(PIXELDISTANCE, hdiff);
+
+    //Serial.print(" beta=");
+    //Serial.println(beta);
+  
+    //_acc += CONST_G * cos(beta) - C_ROLLG*sin(beta) - AIRRES/m*_vel*_vel;
+
+    float aa=CONST_G * cos(beta) *updatedelayms/1000; //Gravity  and m/s^2 time correction
+    float bb=C_ROLL*CONST_G*updatedelayms/1000*sin(beta); //roll resistance
+    if (_vel<0){
+      bb*=-1;
+    }
+    float cc=AIRRES/m*_vel*_vel; //air resistance
+    if (_vel<0){
+      cc*=-1;
+    }
+
+    //Serial.print("aa="); Serial.print(aa);
+    //Serial.print(" bb="); Serial.print(bb);
+    //Serial.print(" cc="); Serial.println(cc);
+    
+
+    _acc += aa - bb - cc;
+    
+
+  }
+
+  _acc*=updatedelayms/1000;
+  
+  _vel += _acc;
+  _pos += _vel/PIXELDISTANCE;
+  /*Serial.print(" Vel=");
+  Serial.print(_vel);
+  Serial.print(" Acc=");
+  Serial.println(_acc);*/
+}
+
+float Wagon::getHeight(int p){
+  if (p<0){
+    p=0;
+  }else if(p>=_numpixels){
+    p=_numpixels-1;
+  }
+  return _height[p];
+}
+
+void Wagon::updateGraphics()
+{
+  for(int i=_pos;i>_pos-_wagonlength;i--){
+    uint32_t c=_strip->Color(0,255,0);
+    if (i==int(_pos)){
+      c=_strip->Color(0,255,100);
+    }
+    _strip->setPixelColor(i,c);
+  }
+  //_strip->setPixelColor(10,_strip->Color(255,0,0));
+}
+
+int Wagon::pos()
+{
+  return _pos;
+}
+
+int Wagon::id()
+{
+  return _id;
+}
+
+bool Wagon::alive()
+{
+  if (_pos>_numpixels){
+    return false;
+  }
+  return true;
+}
+
diff --git a/wagon.h b/wagon.h
new file mode 100644
index 0000000..c5f0f41
--- /dev/null
+++ b/wagon.h
@@ -0,0 +1,31 @@
+#ifndef WAGON_H
+#define WAGON_H
+#include <Adafruit_NeoPixel.h>
+#include <math.h>
+
+class Wagon
+{
+  public:
+    int _id;
+    Wagon(int id,int numpixels,Adafruit_NeoPixel *strip,uint8_t *height, float pos, float wagonlength, float startvel,float startacc);
+    Wagon();
+    bool operator==(const Wagon &r) const;
+    void updatePhysics(float updatedelayms);
+    void updateGraphics();
+    float getHeight(int p);
+    int pos();
+    int id();
+    bool alive();
+  private:
+    int _numpixels;
+    Adafruit_NeoPixel *_strip;
+    float _pos;
+    float _vel;
+    float _acc;
+    float _wagonlength;
+    uint8_t *_height;
+};
+
+#endif
+
+