Changeset 53

Timestamp:

Dec 14, 2004, 1:38:33 PM (20 years ago)

Author:

ole

Message:

Changed alphascaling to be based on hmin, hmiax, alphamin, alphamax which are likely to give better and more intuitive control.

Changed check for division by zero in zrange from zmax ==0 to zrange==0.

Location:

Swollen

Files:

• include/swwreader.h (modified) (2 diffs)
• swollen/main.cpp (modified) (2 diffs)
• swwreader/swwreader.cpp (modified) (3 diffs)

Swollen/include/swwreader.h

@@ -81 +81 @@
     virtual unsigned int getNumberOfTimesteps() {return _ntimesteps;}
 
-    virtual float getAlphaScale() {return _alphascale;}
-    virtual float getAlphaMax() {return _alphamax;}
-    virtual float getAlphaThreshold() {return _alphathreshold;}
-    virtual void setAlphaScale( float value ) {_alphascale = value;}
-    virtual void setAlphaMax( float value ) {_alphamax = value;}
-    virtual void setAlphaThreshold( float value ) {_alphathreshold = value;}
+    virtual float getAlphaMin() {return _alphamin;}    
+    virtual float getAlphaMax() {return _alphamax;}    
+    virtual float getHeightMin() {return _heightmin;}        
+    virtual float getHeightMax() {return _heightmax;}            
 
+    virtual void setAlphaMin( float value ) {_alphamin = value;}    
+    virtual void setAlphaMax( float value ) {_alphamax = value;}        
+    virtual void setHeightMin( float value ) {_heightmin = value;}     
+    virtual void setHeightMax( float value ) {_heightmax = value;}        
+
+    
     virtual triangle_list getConnectivity(unsigned int index) {return _connectivity.at(index);}
 
@@ -146 +150 @@
 
     // alpha based culling
-    float _alphamax, _alphascale, _alphathreshold;
+    float _alphamax, _alphamin, _heightmax, _heightmin;
 
 };

Swollen/swollen/main.cpp

@@ -40 +40 @@
     arguments.getApplicationUsage()->addCommandLineOption("-scale <float>","Vertical scale factor");
     arguments.getApplicationUsage()->addCommandLineOption("-tps <rate>","timesteps per second");
-    arguments.getApplicationUsage()->addCommandLineOption("-alphascale <float>","physical height to transparency scale factor");
-    arguments.getApplicationUsage()->addCommandLineOption("-alphathreshold <float>","transparency lower bound 0-1");
+    arguments.getApplicationUsage()->addCommandLineOption("-hmin <float>","height below which transparency is set to zero");    
+    arguments.getApplicationUsage()->addCommandLineOption("-hmax <float>","Height above which transparency is set to alphamax");       
+    arguments.getApplicationUsage()->addCommandLineOption("-alphamin <float>","transparency value at hmin");    
     arguments.getApplicationUsage()->addCommandLineOption("-alphamax <float>","maximum transparency clamp value");
     arguments.getApplicationUsage()->addCommandLineOption("-nosky","omit background sky");
@@ -90 +91 @@
 
     float tmpfloat;
-    if( arguments.read("-alphascale",tmpfloat) ) sww->setAlphaScale( tmpfloat );
+    if( arguments.read("-hmin",tmpfloat) ) sww->setHeightMin( tmpfloat );  
+    if( arguments.read("-hmax",tmpfloat) ) sww->setHeightMax( tmpfloat );      
+    if( arguments.read("-alphamin",tmpfloat) ) sww->setAlphaMin( tmpfloat );   
     if( arguments.read("-alphamax",tmpfloat) ) sww->setAlphaMax( tmpfloat );
-    if( arguments.read("-alphathreshold",tmpfloat) ) sww->setAlphaThreshold( tmpfloat );
-
+        
 
     // root node

Swollen/swwreader/swwreader.cpp

@@ -118 +118 @@
     _xscale = 1.0 / xrange;
     _yscale = 1.0 / yrange;
-    _zscale = (zmax == 0.0) ? 1.0 : 1.0 / zrange;
+    
+    //_zscale = (zmax == 0.0) ? 1.0 : 1.0 / zrange;
+    //I think this is the right one (OMN) incase of a flat bed that 
+    //isn't necessarily going through z==0
+    _zscale = (zrange == 0.0) ? 1.0 : 1.0 / zrange;
     _xoffset = xmin;
     _yoffset = ymin;
@@ -138 +142 @@
 
     // alpha-scaling defaults
+    _alphamin = 0.4;        
     _alphamax = 0.9;
-    _alphascale = 1.0;
-    _alphathreshold = 0.0;
+    _heightmin = 1.e-3;
+    _heightmax = 1.0;    
 
 
@@ -279 +284 @@
 
     // stage height above bedslope mapped as alpha value
-    float alpha, height;
+    //
+    // Transparancy alpha is calculated as
+    //
+    // alpha = min( a(h-hmin) + alphamin, alphamax),  h >= hmin
+    // alpha = 0,                                     h < hmin
+    //
+    // where a = (alphamax-alphamin)/(hmax-hmin)
+    
+    float alpha, height, _alphascale;
+    _alphascale = (_alphamax - _alphamin) / (_heightmax - _heightmin);
     _stagecolors = new osg::Vec4Array;
     for (iv=0; iv < _npoints; iv++)
     {
         height = _stagevertices->at(iv).z() - _bedslopevertices->at(iv).z();
-        alpha = height / _alphascale;
-        if( alpha > _alphamax ) alpha = _alphamax;
+        
+        if (height < _heightmin) {
+          alpha = 0.0;
+        } else {
+          alpha = _alphascale*(height - _heightmin) + _alphamin;
+          if( alpha > _alphamax ) alpha = _alphamax;      
+        }
         _stagecolors->push_back( osg::Vec4( 1.0, 1.0, 1.0, alpha ) );
     }