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#include "Gradient.h"
Gradient::Gradient( int inNumPoints, double *inPointAnchors,
rgbColor *inPointColors ) {
for( int i=0; i<inNumPoints; i++ ) {
mAnchors.push_back( inPointAnchors[i] );
mColors.push_back( inPointColors[i] );
}
}
rgbColor Gradient::sample( double inLocation ) {
// method copied from minorGems/temp/flame/realtimeFlame.cpp
int numPoints = mAnchors.size();
// linear blend of two points that surround inLocation
int closestPointAbove;
int closestPointBelow;
char foundPoints = false;
for( int i=0; !foundPoints && i<numPoints-1; i++ ) {
if( *( mAnchors.getElement( i ) ) <= inLocation &&
*( mAnchors.getElement( i + 1 ) ) >= inLocation ) {
closestPointAbove = i+1;
closestPointBelow = i;
foundPoints = true;
}
}
double positionAbove = *( mAnchors.getElement( closestPointAbove ) );
double positionBelow = *( mAnchors.getElement( closestPointBelow ) );
double spread = positionAbove - positionBelow;
rgbColor colorAbove = *( mColors.getElement( closestPointAbove ) );
rgbColor colorBelow = *( mColors.getElement( closestPointBelow ) );
// avoid divide-by-zero below
if( spread == 0 ) {
return colorAbove;
}
double weightAbove = (inLocation - positionBelow) / spread;
double weightBelow = (positionAbove - inLocation) / spread;
rgbColor returnColor;
returnColor.r = weightAbove * colorAbove.r + weightBelow * colorBelow.r;
returnColor.g = weightAbove * colorAbove.g + weightBelow * colorBelow.g;
returnColor.b = weightAbove * colorAbove.b + weightBelow * colorBelow.b;
return returnColor;
}
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