dirward FragmentShader(VertexOut vertex, Field <dirward> Dirward, Field <geo> Geo, Field <geo> ShiftedGeo, Field <geo_info> Info, Field <geo_info> ShiftedInfo, [Dir.Vals] float dir)
{
geo
geo_here = Geo[Here],
geo_shift = ShiftedGeo[Here];
if (geo_here.dir == _0)
{
return(dirward.Nothing);
}
geo_info
info_here = Info[Here],
info_shift = ShiftedInfo[Here];
if (geo_here.pos_storage != geo_shift.pos_storage)
{
return(Dirward[Here]);
}
float
dist_here = unpack_val(info_here.xy),
dist_shift = unpack_val(info_shift.xy),
circum = unpack_val(info_here.zw);
float diff = dist_here - dist_shift;
float clockwise = 0, counterclockwise = 0;
if (diff > 0)
{
clockwise = diff;
counterclockwise = circum - diff;
}
else
{
clockwise = circum + diff;
counterclockwise = -diff;
}
dirward output = dirward.Nothing;
output.polarity = clockwise > counterclockwise ? 0 : 1;
output.polarity_set = _true;
return(output);
}
geo_info FragmentShader(VertexOut vertex, Field <geo> Geo, Field <geo_info> Info)
{
geo_info info_here = Info[Here];
geo here = Geo[Here];
if (here.dir == _0)
{
return(geo_info.Zero);
}
vec2 pos_here = vertex.TexCoords * Geo.Size;
vec2 start_pos = geo_pos_id(here);
RelativeIndex GeoStart = (RelativeIndex)(start_pos - pos_here);
geo
right = Geo[GeoStart + RightOne],
up = Geo[GeoStart + UpOne],
left = Geo[GeoStart + LeftOne],
down = Geo[GeoStart + DownOne];
float circum = 0;
if (right.pos_storage == here.pos_storage)
{
circum = max(circum, polar_dist(Info[GeoStart + RightOne]));
}
if (up.pos_storage == here.pos_storage)
{
circum = max(circum, polar_dist(Info[GeoStart + UpOne]));
}
if (left.pos_storage == here.pos_storage)
{
circum = max(circum, polar_dist(Info[GeoStart + LeftOne]));
}
if (down.pos_storage == here.pos_storage)
{
circum = max(circum, polar_dist(Info[GeoStart + DownOne]));
}
// Pack the polar circumference into 2-bytes
set_circumference(ref info_here, circum);
return(info_here);
}
protected static void set_circumference(ref geo_info info, float circumference)
{
info.circumference = pack_val_2byte(circumference);
}
protected static float circumference(geo_info info)
{
return(unpack_val(info.circumference));
}
protected static void set_polar_dist(ref geo_info info, float polar_dist)
{
info.polar_dist = pack_val_2byte(polar_dist);
}
protected static float polar_dist(geo_info info)
{
return(unpack_val(info.polar_dist));
}
geo_info FragmentShader(VertexOut vertex, Field <geo> Geo, Field <geo_info> Info)
{
geo
here = Geo[Here],
right = Geo[RightOne],
up = Geo[UpOne],
left = Geo[LeftOne],
down = Geo[DownOne];
float
dist_right = polar_dist(Info[RightOne]),
dist_up = polar_dist(Info[UpOne]),
dist_left = polar_dist(Info[LeftOne]),
dist_down = polar_dist(Info[DownOne]);
if (here.dir == _0)
{
return(geo_info.Zero);
}
float dist = 0;
// Calculate the geo_id of this cell
geo temp_geo = geo.Nothing;
vec2 pos = vertex.TexCoords * Geo.Size;
set_geo_pos_id(ref temp_geo, pos);
// ... if that geo_id matches the id of the geo info here, then this is the "master" or "12 o' clock" cell of the geodesic line going through this cell.
if (here.pos_storage == temp_geo.pos_storage)
{
// That means its polar distance is 0 by definition.
dist = 0;
}
else
{
// If this geodesic flows into another tile, then the polar distance here should be 1 less than the distance of the tile it flows into.
// This is a fail safe condition that covers degenerate tiles which have nothing flowing into them and only flow out.
if (here.dir == Dir.Left)
{
dist = max(_0, dist_left - 1);
}
if (here.dir == Dir.Right)
{
dist = max(_0, dist_right - 1);
}
if (here.dir == Dir.Up)
{
dist = max(_0, dist_up - 1);
}
if (here.dir == Dir.Down)
{
dist = max(_0, dist_down - 1);
}
// The polar distance is also 1 plus the polar distance of whatever cell comes "before" it (by following the geo backwards "counterclockwise").
if (right.dir == Dir.Left && dist_right >= dist)
{
dist = dist_right + 1;
}
if (left.dir == Dir.Right && dist_left >= dist)
{
dist = dist_left + 1;
}
if (up.dir == Dir.Down && dist_up >= dist)
{
dist = dist_up + 1;
}
if (down.dir == Dir.Up && dist_down >= dist)
{
dist = dist_down + 1;
}
}
// Pack the polar distance into 2-bytes and return it in
geo_info output = geo_info.Zero;
set_polar_dist(ref output, dist);
return(output);
}
