A stenciled letter R

This example produces letter R that appears to be cut into the surface of a tile. Skip to output

center<-c(100,10)
WH<-c(8050,400)
RWH<-c(200,150)
svgR(
  wh=WH,
  defs(
    filter( id='emboss',
      feGaussianBlur(  in1='SourceAlpha', stdDeviation=2, result='blur'),
      feSpecularLighting( in1='blur', surfaceScale=-3, style='lighting-color:white', 
        specularConstant=1, specularExponent=16, result='spec', 
        kernelUnitLength=1, feDistantLight(azimuth=45, elevation=45)
      ),
      feComposite(in1='spec', in2='SourceGraphic', operator='in', result='specOut'),
      feComposite(in1="SourceGraphic", in2="specOut", operator="arithmetic",
                   k1234=c(0,1,1,0), result="embossOut")
    ),
    filter( id="bevel-shadow", xy=c("-50%","-50%"), wh=c("200%","200%"),
      feGaussianBlur(stdDeviation="1", result="blur"),    
      feOffset('in'="blur", dxy=c(1,1), result="blur1"),
      feOffset('in'="blur", dxy=c(0,0), result="blur2"),           
      feComposite('in'="blur2", 'in2'="blur1", operator="arithmetic", 
        k2="1", k3="-1", result="diff1"
      ),
      feFlood(flood.color="back" ),
      feComposite('in2'="diff1", operator="in", result="diff1"),
      feComposite('in'="blur1", 'in2'="blur2", operator="arithmetic",  
        k2="1", k3="-1", result="diff2"
      ),
      feFlood(flood.color="white", flood.opacity="0.5" ),
      feComposite('in2'="diff2", operator="in", result="diff2"),
      feMorphology(operator="erode", radius=2, 'in'="SourceAlpha" ),
      feGaussianBlur(stdDeviation=2, result="blur"),
      feOffset(dxy=c(3,3)),
      feComposite('in2'="SourceAlpha", operator="arithmetic", 
        k2="-1", k3="1", result="shadowDiff"
      ),       
      feFlood(flood.color="black", flood.opacity=".8" ),
      feComposite('in2'="shadowDiff", operator="in", result="shadow"),
      feMerge(
        feMergeNode( 'in'="SourceGraphic"),
        feMergeNode( 'in'="shadow"),
        feMergeNode( 'in'="diff1"),
        feMergeNode( 'in'="diff2")
      )
    )  
  ),
  lapply(1:4, function(i){
    cxy<-(c(5,0)+ RWH )*c(i-.5,.5)
    g(
      rect(id="tmp", cxy=cxy, wh=RWH, stroke="black", 
           fill="rgb(128,128,192)", filter="url(#emboss)"
      ),
      text("R",  cxy=cxy, font.size=144, font.weight="bold",
           stroke="black", fill="rgb(224,224,255)", filter="url(#bevel-shadow)"
      ) 
    )
  })
)