[dasher: 1/11] Tidy EyetrackerFilter co-ordinate transform.

[Patrick Welche <pwelche src gnome org>]

commit f7d29ada06b9f61ade31226e2cfa8bbc18f086f6
Author: Alan Lawrence <acl33 inf phy cam ac uk>
Date:   Wed Jun 23 11:41:20 2010 +0100

    Tidy EyetrackerFilter co-ordinate transform.
    
    I assert this is equivalent to what was there before!

 Src/DasherCore/EyetrackerFilter.cpp |   48 +++++++---------------------------
 Src/DasherCore/EyetrackerFilter.h   |    2 +-
 2 files changed, 11 insertions(+), 39 deletions(-)
---
diff --git a/Src/DasherCore/EyetrackerFilter.cpp b/Src/DasherCore/EyetrackerFilter.cpp
index 8cd6ce5..43018ff 100644
--- a/Src/DasherCore/EyetrackerFilter.cpp
+++ b/Src/DasherCore/EyetrackerFilter.cpp
@@ -30,57 +30,29 @@ bool CEyetrackerFilter::GetSettings(SModuleSettings **pSettings, int *iCount) {
 };
 
 void CEyetrackerFilter::ApplyTransform(myint &iDasherX, myint &iDasherY) {
-  double disty=(myint)GetLongParameter(LP_OY)-iDasherY;
   
-  myint x( iDasherX );
   
-  myint dasherOX=(myint)GetLongParameter(LP_OX); 
-  
-  //  if( iDasherX < dasherOX ) {
-  
-  //cout << "dasherOX: " << dasherOX << endl; 
+  // Y co-ordinate...
   myint dasherOY=(myint)GetLongParameter(LP_OY); 
+  double double_y = ((iDasherY-dasherOY)/(double)(dasherOY) ); // Fraction above the crosshair
+  static const double repulsionparameter=0.5;
+  iDasherY = myint(dasherOY * (1.0 + double_y + (double_y*double_y*double_y * repulsionparameter )));
   
-  // X co-ordinate changes. 
-  double double_x = (x/dasherOX);  // Fraction of way over to crosshair
-  double double_y = -((iDasherY-dasherOY)/(double)(dasherOY) ); // Fraction above the crosshair
-  
-  // FIXME - I have *no* idea how this is supposed to work - someone else fix it and comment the code please!
-  
-  double xmax_y = xmax(double_x, double_y); 
-  
-  if(double_x < xmax_y) { 
-    double_x = xmax_y; 
-  } 
-  
-  //      std::cout << xmax_y << std::endl;
-  
-  x = myint(dasherOX*double_x);
-  
-  // Finished x-coord changes.
-  
-  double repulsionparameter=0.5;
-  iDasherY = myint(dasherOY - (1.0+ double_y*double_y* repulsionparameter ) * disty);
-  
-  if( iDasherX < x )
-    iDasherX = x;
+  // X co-ordinate...  
+  iDasherX = max(iDasherX,myint(GetLongParameter(LP_OX) * xmax(double_y)));
 }
 
-double CEyetrackerFilter::xmax(double x, double y) {
+double CEyetrackerFilter::xmax(double y) {
   // DJCM -- define a function xmax(y) thus:
   // xmax(y) = a*[exp(b*y*y)-1] 
   // then:  if(x<xmax(y) [if the mouse is to the RIGHT of the line xmax(y)]
   // set x=xmax(y).  But set xmax=c if(xmax>c).
   // I would set a=1, b=1, c=16, to start with. 
   
-  int a = 1, b = 1, c = 100;
-  double xmax = a * (exp(b * y * y) - 1);
+  static const int a = 1, b = 1;
+  static const double c = 100;
+  return min(c,a * (exp(b * y * y) - 1));
   //cout << "xmax = " << xmax << endl;
-  
-  if(xmax > c)
-    xmax = c;
-  
-  return xmax;
 }
 
 void CEyetrackerFilter::ApplyAutoCalibration(myint &iDasherX, myint &iDasherY, bool bUpdate) {
diff --git a/Src/DasherCore/EyetrackerFilter.h b/Src/DasherCore/EyetrackerFilter.h
index b1e14f4..3e07828 100644
--- a/Src/DasherCore/EyetrackerFilter.h
+++ b/Src/DasherCore/EyetrackerFilter.h
@@ -15,7 +15,7 @@ class CEyetrackerFilter : public CDefaultFilter {
  private:
   virtual void ApplyAutoCalibration(myint &iDasherX, myint &iDasherY, bool bUpdate);
   virtual void ApplyTransform(myint &iDasherX, myint &iDasherY);
-  double xmax(double x, double y);
+  double xmax(double y);
 
   myint m_iYAutoOffset;