vec4 vsurface = water_surf( halfview, surfnorm, depthvalue, beneath, above );
vsurface.a -= fdist;
oColour = mix( vsurface, vec4(1.0,1.0,1.0,0.5), fband );
vec4 vsurface = water_surf( halfview, surfnorm, depthvalue, beneath, above );
vsurface.a -= fdist;
oColour = mix( vsurface, vec4(1.0,1.0,1.0,0.5), fband );