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fgdata/Nasal/view.nas

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##
## view.nas
##
## Nasal code for implementing view-specific functionality.
# Dynamically calculate limits so that it takes STEPS iterations to
# traverse the whole range, the maximum FOV is fixed at 120 degrees,
# and the minimum corresponds to normal maximum human visual acuity
# (~1 arc minute of resolution, although apparently people vary widely
# in this ability). Quick derivation of the math:
#
# mul^steps = max/min
# steps * ln(mul) = ln(max/min)
# mul = exp(ln(max/min) / steps)
STEPS = 40;
ACUITY = 1/60; # Maximum angle subtended by one pixel (== 1 arc minute)
max = min = mul = 0;
calcMul = func {
max = 120; # Fixed at 120 degrees
min = getprop("/sim/startup/xsize") * ACUITY;
mul = math.exp(math.ln(max/min) / STEPS);
}
##
# Handler. Increase FOV by one step
#
increase = func {
calcMul();
val = fovProp.getValue() * mul;
if(val == max) { return; }
if(val > max) { val = max }
fovProp.setDoubleValue(val);
gui.popupTip(sprintf("FOV: %.1f", val));
}
##
# Handler. Decrease FOV by one step
#
decrease = func {
calcMul();
val = fovProp.getValue() / mul;
fovProp.setDoubleValue(val);
gui.popupTip(sprintf("FOV: %.1f%s", val, val < min ? " (overzoom)" : ""));
}
##
# Handler. Reset FOV to default.
#
var resetFOV = func {
setprop("/sim/current-view/field-of-view",
getprop("/sim/current-view/config/default-field-of-view-deg"));
}
var resetViewPos = func {
var v = views[getprop("/sim/current-view/view-number")].getNode("config");
setprop("/sim/current-view/x-offset-m", v.getNode("x-offset-m", 1).getValue() or 0);
setprop("/sim/current-view/y-offset-m", v.getNode("y-offset-m", 1).getValue() or 0);
setprop("/sim/current-view/z-offset-m", v.getNode("z-offset-m", 1).getValue() or 0);
}
var resetViewDir = func {
setprop("/sim/current-view/goal-heading-offset-deg",
getprop("/sim/current-view/config/heading-offset-deg"));
setprop("/sim/current-view/goal-pitch-offset-deg",
getprop("/sim/current-view/config/pitch-offset-deg"));
setprop("/sim/current-view/goal-roll-offset-deg",
getprop("/sim/current-view/config/roll-offset-deg"));
}
##
# Handler. Step to the next (force=1) or next enabled view.
#
var stepView = func(step, force = 0) {
step = step > 0 ? 1 : -1;
var n = getprop("/sim/current-view/view-number");
for (var i = 0; i < size(views); i += 1) {
n += step;
if (n < 0)
n = size(views) - 1;
elsif (n >= size(views))
n = 0;
if (force or (var e = views[n].getNode("enabled")) == nil or e.getValue())
break;
}
setprop("/sim/current-view/view-number", n);
# And pop up a nice reminder
gui.popupTip(views[n].getNode("name").getValue());
}
##
# Get view index by name.
#
var indexof = func(name) {
forindex (var i; views)
if (views[i].getNode("name", 1).getValue() == name)
return i;
return nil;
}
##
# Standard view "slew" rate, in degrees/sec.
#
VIEW_PAN_RATE = 60;
##
# Pans the view horizontally. The argument specifies a relative rate
# (or number of "steps" -- same thing) to the standard rate.
#
panViewDir = func(step) {
if (getprop("/sim/freeze/master"))
prop = "/sim/current-view/heading-offset-deg";
else
prop = "/sim/current-view/goal-heading-offset-deg";
controls.slewProp(prop, step * VIEW_PAN_RATE);
}
##
# Pans the view vertically. The argument specifies a relative rate
# (or number of "steps" -- same thing) to the standard rate.
#
panViewPitch = func(step) {
if (getprop("/sim/freeze/master"))
prop = "/sim/current-view/pitch-offset-deg";
else
prop = "/sim/current-view/goal-pitch-offset-deg";
controls.slewProp(prop, step * VIEW_PAN_RATE);
}
##
# Reset view to default using current view manager (see default_handler).
#
var resetView = func {
manager.reset();
}
##
# Default view handler used by view.manager.
#
var default_handler = {
reset : func {
resetViewDir();
resetFOV();
},
};
##
# View manager. Administrates optional Nasal view handlers.
# Usage: view.manager.register(<view-id>, <view-handler>);
#
# view-id: the view's name, e.g. "Chase View"
# view-handler: a hash with any combination of the functions listed in the
# following example, or none at all. Only define the interface
# functions that you really need! The hash may contain local
# variables and other, non-interface functions.
#
# Example:
#
# var some_view_handler = {
# init : func {}, # called only once at startup
# start : func {}, # called when view is switched to our view
# stop : func {}, # called when view is switched away from our view
# reset : func {}, # called with view.resetView()
# update : func { 0 }, # called iteratively if defined. Must return
# }; # interval in seconds until next invocation
# # Don't define it if you don't need it!
#
# view.manager.register("Some View", some_view_handler);
#
#
var manager = {
current : { node: nil, handler: default_handler },
init : func {
me.views = {};
me.loopid = 0;
var viewnodes = props.globals.getNode("sim").getChildren("view");
forindex (var i; viewnodes)
me.views[i] = { node: viewnodes[i], handler: default_handler };
setlistener("/sim/current-view/view-number", func(n) {
manager.set_view(n.getValue());
}, 1);
},
register : func(which, handler = nil) {
if (num(which) == nil)
which = view.indexof(which);
if (handler == nil)
handler = default_handler;
me.views[which]["handler"] = handler;
if (contains(handler, "init"))
handler.init(me.views[which].node);
me.set_view();
},
set_view : func(which = nil) {
if (which == nil)
which = getprop("/sim/current-view/view-number");
elsif (num(which) == nil)
which = view.indexof(which);
me.loopid += 1;
if (contains(me.current.handler, "stop"))
me.current.handler.stop();
me.current = me.views[which];
if (contains(me.current.handler, "start"))
me.current.handler.start();
if (contains(me.current.handler, "update"))
me._loop_(me.loopid += 1);
},
reset : func {
if (contains(me.current.handler, "reset"))
me.current.handler.reset();
else
default_handler.reset();
},
_loop_ : func(id) {
id == me.loopid or return;
settimer(func { me._loop_(id) }, me.current.handler.update());
},
};
##
# View handler for fly-by view.
#
var fly_by_view_handler = {
init : func {
me.latN = props.globals.getNode("/sim/viewer/latitude-deg", 1);
me.lonN = props.globals.getNode("/sim/viewer/longitude-deg", 1);
me.altN = props.globals.getNode("/sim/viewer/altitude-ft", 1);
me.hdgN = props.globals.getNode("/orientation/heading-deg", 1);
setlistener("/sim/signals/reinit", func(n) { n.getValue() or me.reset() });
setlistener("/sim/crashed", func(n) { n.getValue() and me.reset() });
setlistener("/sim/freeze/replay-state", func {
settimer(func { me.reset() }, 1); # time for replay to catch up
});
me.reset();
},
start : func {
me.reset();
},
reset: func {
me.chase = -getprop("/sim/chase-distance-m");
me.course = me.hdgN.getValue();
me.last = geo.aircraft_position();
me.setpos(1);
me.dist = 20;
},
setpos : func(force = 0) {
var pos = geo.aircraft_position();
# check if the aircraft has moved enough
var dist = me.last.distance_to(pos);
if (dist < 1.7 * me.chase and !force)
return 1.13;
# "predict" and remember next aircraft position
var course = me.hdgN.getValue();
var delta_alt = (pos.alt() - me.last.alt()) * 0.5;
pos.apply_course_distance(course, dist * 0.8);
pos.set_alt(pos.alt() + delta_alt);
me.last.set(pos);
# apply random deviation
var radius = me.chase * (0.5 * rand() + 0.7);
var agl = getprop("/position/altitude-agl-ft") * geo.FT2M;
if (agl > me.chase)
var angle = rand() * 2 * math.pi;
else
var angle = ((2 * rand() - 1) * 0.15 + 0.5) * (rand() < 0.5 ? -math.pi : math.pi);
var dev_alt = math.cos(angle) * radius;
var dev_side = math.sin(angle) * radius;
pos.apply_course_distance(course + 90, dev_side);
# and make sure it's not under ground
var lat = pos.lat();
var lon = pos.lon();
var alt = pos.alt();
var elev = geo.elevation(lat, lon);
if (elev != nil) {
elev += 2; # min elevation
if (alt + dev_alt < elev and dev_alt < 0)
dev_alt = -dev_alt;
if (alt + dev_alt < elev)
alt = elev;
else
alt += dev_alt;
}
# set new view point
me.latN.setValue(lat);
me.lonN.setValue(lon);
me.altN.setValue(alt * geo.M2FT);
return 6.3;
},
update : func {
return me.setpos();
},
};
#------------------------------------------------------------------------------
#
# Saves/restores/moves the view point (position, orientation, field-of-view).
# Moves are interpolated with sinusoidal characteristic. There's only one
# instance of this class, available as "view.point".
#
# Usage:
# view.point.save(); ... save current view and return reference to
# saved values in the form of a props.Node
#
# view.point.restore(); ... restore saved view parameters
#
# view.point.move(<prop> [, <time>]);
# ... set view parameters from a props.Node with
# optional move time in seconds. <prop> may be
# nil, in which case nothing happens.
#
# A parameter set as expected by set() and returned by save() is a props.Node
# object containing any (or none) of these children:
#
# <heading-offset-deg>
# <pitch-offset-deg>
# <roll-offset-deg>
# <x-offset-m>
# <y-offset-m>
# <z-offset-m>
# <field-of-view>
# <move-time-sec>
#
# The <move-time> isn't really a property of the view, but is available
# for convenience. The time argument in the move() method overrides it.
##
# Normalize angle to -180 <= angle < 180
#
var normdeg = func(a) {
while (a >= 180) {
a -= 360;
}
while (a < -180) {
a += 360;
}
return a;
}
##
# Manages one translation/rotation axis. (For simplicity reasons the
# field-of-view parameter is also managed by this class.)
#
var ViewAxis = {
new : func(prop) {
var m = { parents : [ViewAxis] };
m.prop = props.globals.getNode(prop, 1);
if (m.prop.getType() == "NONE") {
m.prop.setDoubleValue(0);
}
m.from = m.to = m.prop.getValue();
return m;
},
reset : func {
me.from = me.to = normdeg(me.prop.getValue());
},
target : func(v) {
me.to = normdeg(v);
},
move : func(blend) {
me.prop.setValue(me.from + blend * (me.to - me.from));
},
};
##
# view.point: handles smooth view movements
#
var point = {
init : func {
me.axes = {
"heading-offset-deg" : ViewAxis.new("/sim/current-view/goal-heading-offset-deg"),
"pitch-offset-deg" : ViewAxis.new("/sim/current-view/goal-pitch-offset-deg"),
"roll-offset-deg" : ViewAxis.new("/sim/current-view/goal-roll-offset-deg"),
"x-offset-m" : ViewAxis.new("/sim/current-view/x-offset-m"),
"y-offset-m" : ViewAxis.new("/sim/current-view/y-offset-m"),
"z-offset-m" : ViewAxis.new("/sim/current-view/z-offset-m"),
"field-of-view" : ViewAxis.new("/sim/current-view/field-of-view"),
};
me.storeN = props.Node.new();
me.dtN = props.globals.getNode("/sim/time/delta-realtime-sec", 1);
me.currviewN = props.globals.getNode("/sim/current-view", 1);
me.blend = 0;
me.loop_id = 0;
props.copy(props.globals.getNode("/sim/view/config"), me.storeN);
},
save : func {
me.storeN = props.Node.new();
props.copy(me.currviewN, me.storeN);
return me.storeN;
},
restore : func {
me.move(me.storeN);
},
move : func(prop, time = nil) {
prop != nil or return;
foreach (var a; keys(me.axes)) {
var n = prop.getNode(a);
me.axes[a].reset();
if (n != nil) {
me.axes[a].target(n.getValue());
}
}
var m = prop.getNode("move-time-sec");
if (m != nil) {
time = m.getValue();
}
if (time == nil) {
time = 1;
}
me.blend = -1; # range -1 .. 1
me._loop_(me.loop_id += 1, time);
},
_loop_ : func(id, time) {
me.loop_id == id or return;
me.blend += me.dtN.getValue() / time;
if (me.blend > 1) {
me.blend = 1;
}
var b = (math.sin(me.blend * math.pi / 2) + 1) / 2; # range 0 .. 1
foreach (var a; keys(me.axes)) {
me.axes[a].move(b);
}
if (me.blend < 1) {
settimer(func { me._loop_(id, time) }, 0);
}
},
};
var views = nil;
var fovProp = nil;
_setlistener("/sim/signals/nasal-dir-initialized", func {
views = props.globals.getNode("/sim").getChildren("view");
fovProp = props.globals.getNode("/sim/current-view/field-of-view");
point.init();
});
_setlistener("/sim/signals/fdm-initialized", func {
foreach (var v; views) {
var index = v.getIndex();
if (index > 6 and index < 100) {
globals["view"] = nil;
die("\n***\n*\n* Illegal use of reserved view index "
~ index ~ ". Use indices >= 100!\n*\n***");
} elsif (index >= 100 and index < 200) {
var e = v.getNode("enabled");
if (e != nil) {
aircraft.data.add(e);
e.setAttribute("userarchive", 0);
}
}
}
manager.init();
manager.register("Fly-By View", fly_by_view_handler);
});
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