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.TH osgearth_sharedlayer 1 "05 May 2016" "" ""
.SH NAME
osgearth_sharedlayer \- demonstration of shared layers
.SH SYNOPSIS
'nh
.fi
.ad l
\fBosgearth_sharedlayer\fR \kx
.if (\nx>(\n(.l/2)) .nr x (\n(.l/5)
'in \n(.iu+\nxu
\fB--shapefile\fR \fIfile.shp\fR 
'in \n(.iu-\nxu
.ad b
'hy
.SH DESCRIPTION
\fBosgearth_sharedlayer\fR is a sample program which
demonstrates the use of shared layers.
A shared image layer is one that becomes available to other image layers
during the rendering phase.
Thus if you share a layer, you can access it in a customer shader
and use it to modulate another layer.
.PP
In this example, we render a masking layer from a shapefile using the
rasterization (agglite) driver.
We don't draw this layer directly;
instead we use it as a mask and use that mask to modulate the imagery
layer from a custom shader, drawing random colors where the mask exists.
.SH OPTIONS
.TP 
\*(T<\fB\-\-shapefile\fR\*(T> \fIfile.shp\fR
Path to the shapefile