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fgdata/Nasal/local_weather/weather_dynamics.nas

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########################################################
# routines to simulate cloud wind drift and evolution
# Thorsten Renk, October 2010
########################################################
# function purpose
#
# get_windfield to get the current wind in the tile
# timing_loop to provide accurate timing information for wind drift calculations
# quadtree_loop to manage drift of clouds in the field of view
# weather_dynamics_loop to manage drift of weather effects, tile centers and interpolation points
# convective_loop to regularly recreate convective clouds
# generate_quadtree_structure to generate a quadtree data structure used for managing the visual field
# sort_into_quadtree to sort objects into a quadtree structure
# sorting_recursion to recursively sort into a quadree (helper)
# quadtree_recursion to search the quadtree for objects in the visual field
# check_visibility to check if a quadrant is currently visible
# move_tile to move tile coordinates in the wind
# get_cartesian to get local Cartesian coordinates out of coordinates
####################################################
# get the windfield for a given location and altitude
# (currently constant, but supposed to be local later)
####################################################
var get_windfield = func (tile_index) {
if (hardcoded_clouds_flag == 1)
{
var wind_direction = local_weather.wind.current[0];
var windspeed = local_weather.wind.current[1] * kt_to_ms;
var windfield_x = -windspeed * math.sin(wind_direction * math.pi/180.0);
var windfield_y = -windspeed * math.cos(wind_direction * math.pi/180.0);
return [windfield_x,windfield_y];
}
if ((local_weather.wind_model_flag == 1) or (local_weather.wind_model_flag == 3))
{
var windspeed = tile_wind_speed[0] * kt_to_ms;
var wind_direction = tile_wind_direction[0];
}
else if ((local_weather.wind_model_flag ==2) or (local_weather.wind_model_flag == 4) or (local_weather.wind_model_flag == 5))
{
var windspeed = tile_wind_speed[tile_index-1] * kt_to_ms;
var wind_direction = tile_wind_direction[tile_index-1];
}
var windfield_x = -windspeed * math.sin(wind_direction * math.pi/180.0);
var windfield_y = -windspeed * math.cos(wind_direction * math.pi/180.0);
return [windfield_x,windfield_y];
}
var get_wind_direction = func (tile_index) {
if (hardcoded_clouds_flag == 1)
{
return local_weather.wind.current[0];
}
if ((local_weather.wind_model_flag == 1) or (local_weather.wind_model_flag == 3))
{
return tile_wind_direction[0];
}
else if ((local_weather.wind_model_flag ==2) or (local_weather.wind_model_flag == 4) or (local_weather.wind_model_flag == 5))
{
return tile_wind_direction[tile_index-1];
}
}
var get_wind_speed = func (tile_index) {
if (hardcoded_clouds_flag == 1)
{
return local_weather.wind.current[1];
}
if ((local_weather.wind_model_flag == 1) or (local_weather.wind_model_flag == 3))
{
return tile_wind_speed[0];
}
else if ((local_weather.wind_model_flag ==2) or (local_weather.wind_model_flag == 4) or (local_weather.wind_model_flag == 5))
{
return tile_wind_speed[tile_index-1];
}
}
########################################################
# timing loop
# this gets the accurate time since the start of weather dynamics
# and hence the timestamps for cloud evolution since
# the available elapsed-time-sec is not accurate enough
########################################################
var timing_loop = func {
if (local_weather.local_weather_running_flag == 0) {return;}
dt_lw = getprop("/sim/time/delta-sec");
time_lw = time_lw + dt_lw;
# this is a really ugly hack to get the sun angle information to the shaders
# directly referencing /sim/time/sun-angle-rad as uniform doesn't
# work since that is a tied property
#var sun_angle = 1.57079632675 - getprop("/sim/time/sun-angle-rad");
#var terminator_offset = sun_angle / 0.017451 * 110000.0;# + 250000.0;
#setprop("/environment/terminator-relative-position-m",terminator_offset);
var viewpos = geo.viewer_position();
# setprop("/environment/alt-in-haze-m", getprop("/environment/ground-haze-thickness-m")-viewpos.alt());
#setprop("/sim/rendering/eye-altitude-m", viewpos.alt());
if (local_weather.presampling_flag == 1)
{
var mean_terrain_elevation_m = ft_to_m * local_weather.current_mean_alt ; }
else
{var mean_terrain_elevation_m = 0.0;}
setprop("/environment/mean-terrain-elevation-m", mean_terrain_elevation_m);
if (getprop(lw~"timing-loop-flag") ==1) {settimer(timing_loop, 0);}
}
###########################################################
# quadtree loop
# the quadtree loop is a fast loop updating the position
# of visible objects in the field of view only
###########################################################
var quadtree_loop = func {
if (local_weather.local_weather_running_flag == 0) {return;}
var vangle = 0.55 * getprop("/sim/current-view/field-of-view");
var viewdir = getprop("/sim/current-view/goal-heading-offset-deg");
var lat = getprop("position/latitude-deg");
var lon = getprop("position/longitude-deg");
var course = getprop("orientation/heading-deg");
cloud_counter = 0;
# pre-calculate trigonometry
tan_vangle = math.tan(vangle * math.pi/180.0);
# use the quadtree to move clouds inside the field of view
var tiles = props.globals.getNode(lw~"tiles").getChildren("tile");
foreach (var t; tiles)
{
var generated_flag = t.getNode("generated-flag").getValue();
if ((generated_flag == 1) or (generated_flag ==2))
{
var index = t.getNode("tile-index").getValue();
current_tile_index_wd = index;
var blat = t.getNode("latitude-deg").getValue();
var blon = t.getNode("longitude-deg").getValue();
var alpha = t.getNode("orientation-deg").getValue();
var xy_vec = get_cartesian(blat, blon, alpha, lat, lon);
var beta = course - alpha - viewdir ;
cos_beta = math.cos(beta * math.pi/180.0);
sin_beta = math.sin(beta * math.pi/180.0);
plane_x = xy_vec[0]; plane_y = xy_vec[1];
windfield = get_windfield(index);
quadtree_recursion(cloudQuadtrees[index-1],0,1,0.0,0.0);
}
}
# dynamically adjust the range of the processed view field
# if there are plenty of moving clouds nearby, no one pays attention to the small motion of distant clouds
# price to pay is that some clouds appear to jump once they get into range
if (cloud_counter < 0.5 * max_clouds_in_loop) {view_distance = view_distance * 1.1;}
else if (cloud_counter > max_clouds_in_loop) {view_distance = view_distance * 0.9;}
if (view_distance > weather_tile_management.cloud_view_distance) {view_distance = weather_tile_management.cloud_view_distance;}
#print(cloud_counter, " ", view_distance/1000.0);
# shift the tile centers with the windfield
var tiles = props.globals.getNode("local-weather/tiles", 1).getChildren("tile");
foreach (var t; tiles) {move_tile(t);}
# loop over
if (getprop(lw~"dynamics-loop-flag") ==1) {settimer(quadtree_loop, 0);}
}
###########################################################
# weather_dynamics_loop
# the weather dynamics loop is a slow loop updating
# position and state of invisible objects, currently
# effect volumes and weather stations
###########################################################
var weather_dynamics_loop = func (index, cindex) {
if (local_weather.local_weather_running_flag == 0) {return;}
var n = 20;
var nc = 1;
var csize = weather_tile_management.n_cloudSceneryArray;
var i_max = index + n;
if (i_max > local_weather.n_effectVolumeArray) {i_max = local_weather.n_effectVolumeArray;}
var ecount = 0;
for (var i = index; i < i_max; i = i+1)
{
var ev = local_weather.effectVolumeArray[i];
if (ev.index !=0)
{ev.move();}
if ((ev.lift_flag == 2) and (rand() < 0.05) and (local_weather.presampling_flag == 1))
{
if (local_weather.dynamical_convection_flag ==1)
{
ev.correct_altitude_and_age();
if (ev.flt > 1.2) # beyond 1.0, sink is still active
{
local_weather.effectVolumeArray = weather_tile_management.delete_from_vector(local_weather.effectVolumeArray,i);
local_weather.n_effectVolumeArray = local_weather.n_effectVolumeArray - 1;
i = i-1; i_max = i_max -1; ecount = ecount + 1;
}
}
else
{ev.correct_altitude();}
}
}
setprop(lw~"effect-volumes/number",getprop(lw~"effect-volumes/number")- ecount);
index = index + n;
if (i >= local_weather.n_effectVolumeArray) {index = 0;}
var ccount = 0;
if (csize > 0)
{
var j_max = cindex + nc;
if (j_max > csize -1) {j_max = csize-1;}
for (var j = cindex; j < j_max; j = j+1)
{
var cs = weather_tile_management.cloudSceneryArray[j];
#cs.move();
if (cs.type !=0)
{
if ((rand() < 0.1) and (local_weather.presampling_flag == 1))
{
if (local_weather.dynamical_convection_flag ==1)
{
cs.correct_altitude_and_age();
if (cs.flt > 1.0) # the cloud has reached its maximum age and decays
{
cs.removeNodes();
weather_tile_management.cloudSceneryArray = weather_tile_management.delete_from_vector(weather_tile_management.cloudSceneryArray,j);
ccount = ccount + 1;
}
}
else
{
cs.correct_altitude();
}
}
}
}
cindex = cindex + nc;
if (j >= csize) {cindex = 0;}
}
foreach (var s; local_weather.weatherStationArray)
{
s.move();
}
foreach (var a; local_weather.atmosphereIpointArray)
{
a.move();
}
if (getprop(lw~"dynamics-loop-flag") ==1) {settimer( func {weather_dynamics_loop(index, cindex); },0);}
}
###########################################################
# convective evolution loop
###########################################################
var convective_loop = func {
if (local_weather.local_weather_running_flag == 0) {return;}
# a 30 second loop needs a different strategy to end, otherwise there is trouble if it is restarted while still running
if (convective_loop_kill_flag == 1)
{convective_loop_kill_flag = 0; return;}
var cloud_respawning_interval_s = 30.0;
if (getprop(lw~"tmp/thread-status") == "placing")
{if (getprop(lw~"convective-loop-flag") ==1) {settimer( func {convective_loop()}, 5.0);} return;}
# open the system for write status
setprop(lw~"tmp/buffer-status","placing");
if (local_weather.debug_output_flag == 1)
{print("Respawning convective clouds...");}
for(var i = 0; i < 9; i = i + 1)
{
var index = getprop(lw~"tiles/tile["~i~"]/tile-index");
if ((index == -1) or (index == 0)) {continue;}
if (getprop(lw~"tiles/tile["~i~"]/generated-flag") != 2)
{continue;}
var strength = tile_convective_strength[index-1];
var alt = tile_convective_altitude[index-1];
var n = weather_tiles.get_n(strength);
if (local_weather.detailed_clouds_flag == 1)
{n = int(0.7 * n);}
n = n/cloud_convective_lifetime_s * cloud_respawning_interval_s * math.sqrt(0.35);
var n_res = n - int(n);
n = int(n);
if (rand() < n_res) {n=n+1;}
if (local_weather.debug_output_flag == 1)
{print("Tile: ", index, " n: ", n);}
var lat = getprop(lw~"tiles/tile["~i~"]/latitude-deg");
var lon = getprop(lw~"tiles/tile["~i~"]/longitude-deg");
var alpha = getprop(lw~"tiles/tile["~i~"]/orientation-deg");
compat_layer.buffered_tile_latitude = lat;
compat_layer.buffered_tile_longitude = lon;
compat_layer.buffered_tile_alpha = alpha;
compat_layer.buffered_tile_index = index;
setprop(lw~"tmp/buffer-tile-index", index);
if (local_weather.presampling_flag == 1)
{var alt_offset = local_weather.alt_20_array[index -1];}
else
{var alt_offset = getprop(lw~"tmp/tile-alt-offset-ft");}
local_weather.recreate_cumulus(lat,lon, alt + alt_offset, alpha, n, 20000.0, index);
}
# close the write process
setprop(lw~"tmp/buffer-status","idle");
if (getprop(lw~"convective-loop-flag") ==1) {settimer(convective_loop, cloud_respawning_interval_s);}
}
###########################################################
# generate quadtree structure
###########################################################
var generate_quadtree_structure = func (depth, tree_base_vec) {
var c_vec = [];
for (var i=0; i<4; i=i+1)
{
if (depth == quadtree_depth)
{var c = [];}
else
{var c = generate_quadtree_structure(depth+1, tree_base_vec);}
if (depth==0)
{append(tree_base_vec,c); }
else
{append(c_vec,c); }
}
if (depth ==0) {return tree_base_vec;} else {return c_vec;}
}
###########################################################
# sort into quadtree
###########################################################
var sort_into_quadtree = func (blat, blon, alpha, lat, lon, tree, object) {
var xy_vec = get_cartesian (blat, blon, alpha, lat, lon);
sorting_recursion (xy_vec[0], xy_vec[1], tree, object, 0);
}
var sorting_recursion = func (x, y, tree, object, depth) {
if (depth == quadtree_depth+1) {append(tree,object); return;}
var length_scale = 20000.0 / math.pow(2,depth);
# print("depth: ", depth, "x: ", x, "y: ",y);
if (y > 0.0)
{
if (x < 0.0)
{var v = tree[0]; x = x + 0.5 * length_scale; y = y - 0.5 * length_scale;}
else
{var v = tree[1]; x = x - 0.5 * length_scale; y = y - 0.5 * length_scale;}
}
else
{
if (x < 0.0)
{var v = tree[2]; x = x + 0.5 * length_scale; y = y + 0.5 * length_scale;}
else
{var v = tree[3]; x = x - 0.5 * length_scale; y = y + 0.5 * length_scale;}
}
sorting_recursion(x, y, v, object, depth+1);
}
####################################################
# quadtree recursive search
####################################################
var quadtree_recursion = func (tree, depth, flag, qx, qy) {
# flag = 0: quadrant invisible, stop search
# flag = 1: quadrant partially visible, continue search with visibility tests
# flag = 2: quadrant fully visible, no further visibility test needed
if (depth == quadtree_depth +1)
{
foreach (var c; tree)
{
c.move();
c.to_target_alt();
cloud_counter = cloud_counter + 1;
}
return;
}
for (var i =0; i<4; i=i+1)
{
if (flag==2) {quadtree_recursion(tree[i], depth+1, flag, qx, qy);}
else if (flag==1)
{
# compute the subquadrant coordinates
var length_scale = 20000.0 / math.pow(2,depth);
if (i==0) {var qxnew = qx - 0.5 * length_scale; var qynew = qy + 0.5 * length_scale;}
else if (i==1) {var qxnew = qx + 0.5 * length_scale; var qynew = qy + 0.5 * length_scale;}
else if (i==2) {var qxnew = qx - 0.5 * length_scale; var qynew = qy - 0.5 * length_scale;}
else if (i==3) {var qxnew = qx + 0.5 * length_scale; var qynew = qy - 0.5 * length_scale;}
var newflag = check_visibility(qxnew,qynew, length_scale);
if (newflag!=0) {quadtree_recursion(tree[i], depth+1, newflag, qxnew, qynew);}
}
}
}
####################################################
# quadrant visibility test
####################################################
var check_visibility = func (qx,qy, length_scale) {
# (qx,qy) are the quadrant coordinates in tile local Cartesian
# beta is the plane course in the tile local Cartesian
# the function returns a flag: 0: invisible 1: partially visible, track further 2: fully visible
# first translate/rotate (qx,qy) into the plane system
qx = qx - plane_x; qy = qy - plane_y;
var x = qx * cos_beta - qy * sin_beta;
var y = qy * cos_beta + qx * sin_beta;
# now get the maximum and minimum quadrant extensions
var ang_factor = abs(cos_beta) + abs(sin_beta); # a square seen from an angle extends larger
var xmax = x + 0.5 * length_scale * ang_factor;
var xmin = x - 0.5 * length_scale * ang_factor;
var ymax = y + 0.5 * length_scale * ang_factor;
var ymin = y - 0.5 * length_scale * ang_factor;
# now do visibility checks
if ((ymax < 0.0) and (ymin < 0.0)) # quadrant is behind us, we can never see it
{return 0;}
if (ymin > view_distance) # the quadrant is beyond visible range
{return 0;}
var xcomp_min = ymin * tan_vangle;
var xcomp_max = ymax * tan_vangle;
if ((ymax > 0.0) and (ymin < 0.0)) # object is at most partially visible, check if in visual cone at ymax
{
if ((xmax < -xcomp_max) and (xmin < -xcomp_max)) {return 0;}
if ((xmax > xcomp_max) and (xmin > xcomp_max)) {return 0;}
return 1;
}
# now we know the quadrant must be in front
# check if invisible
if ((xmax < -xcomp_max) and (xmin < -xcomp_max)) {return 0;}
if ((xmax > xcomp_max) and (xmin > xcomp_max)) {return 0;}
# check if completely visible
if ((xmax > -xcomp_min) and (xmin > -xcomp_min) and (xmax < xcomp_min) and (xmin < xcomp_min))
{return 2;}
# at this point, it must be partially visible
return 1;
}
####################################################
# move a tile
####################################################
var move_tile = func (t) {
# get the old spacetime position of the tile
var lat_old = t.getNode("latitude-deg").getValue();
var lon_old = t.getNode("longitude-deg").getValue();
var timestamp = t.getNode("timestamp-sec").getValue();
var tile_index = t.getNode("tile-index").getValue();
# if the tile is not yet generated, we use the windfield of the tile we're in
if (tile_index == -1)
{
tile_index = props.globals.getNode(lw~"tiles").getChild("tile",4).getNode("tile-index").getValue();
}
# get windfield and time since last update
var windfield = get_windfield(tile_index);
var dt = time_lw - timestamp;
# update the spacetime position of the tile
t.getNode("latitude-deg",1).setValue(lat_old + windfield[1] * dt * local_weather.m_to_lat);
t.getNode("longitude-deg",1).setValue(lon_old + windfield[0] * dt * local_weather.m_to_lon);
t.getNode("timestamp-sec",1).setValue(weather_dynamics.time_lw);
}
###########################################################
# get local Cartesian coordinates
###########################################################
var get_cartesian = func (blat, blon, alpha, lat, lon) {
var xy_vec = [];
var phi = alpha * math.pi/180.0;
var delta_lat = lat - blat;
var delta_lon = lon - blon;
var x1 = delta_lon * lon_to_m;
var y1 = delta_lat * lat_to_m;
var x = x1 * math.cos(phi) - y1 * math.sin(phi);
var y = y1 * math.cos(phi) + x1 * math.sin(phi);
append(xy_vec,x);
append(xy_vec,y);
return xy_vec;
}
################################
# globals, constants, properties
################################
var lat_to_m = 110952.0; # latitude degrees to meters
var m_to_lat = 9.01290648208234e-06; # meters to latitude degrees
var ft_to_m = 0.30480;
var m_to_ft = 1.0/ft_to_m;
var inhg_to_hp = 33.76389;
var hp_to_inhg = 1.0/inhg_to_hp;
var kt_to_ms = 0.514;
var ms_to_kt = 1./kt_to_ms;
var lon_to_m = 0.0; # needs to be calculated dynamically
var m_to_lon = 0.0; # we do this on startup
# abbreviations
var lw = "/local-weather/";
# globals
var time_lw = 0.0;
var dt_lw = 0.0;
var max_clouds_in_loop = 250;
var cloud_max_vertical_speed_fts = 30.0;
var cloud_convective_lifetime_s = 1800.0; # max. lifetime of convective clouds
var convective_loop_kill_flag = 0;
# the quadtree structure
var cloudQuadtrees = [];
var quadtree_depth = 3;
# the wind info for the individual weather tiles
# (used for 'constant in tile' wind model)
var tile_wind_direction = [];
var tile_wind_speed = [];
var tile_convective_altitude = [];
var tile_convective_strength = [];
# define these as global, as we need to evaluate them only once per frame
# but use them over and over
var tan_vangle = 0;
var cos_beta = 0;
var sin_beta = 0;
var plane_x = 0;
var plane_y = 0;
var windfield = [];
var current_tile_index_wd = 0;
var cloud_counter = 0;
var view_distance = 30000.0;
# create the loop flags
setprop(lw~"timing-loop-flag",0);
setprop(lw~"dynamics-loop-flag",0);