131 lines
3.9 KiB
Text
131 lines
3.9 KiB
Text
##
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## view.nas
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##
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## Nasal code for implementing view-specific functionality. Right
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## now, it does intelligent FOV scaling in the view.increase() and
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## view.decrease() handlers.
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##
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#
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# This is a neat trick. We want these globals to be initialized at
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# startup, but there is no guarantee that the props.nas module will be
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# loaded yet when we are run. So set the values to nil at startup (so
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# that there is a value in the lexical environment -- otherwise
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# assigning them in INIT() will only make local variables),
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# and then assign them from inside a timer that we set to run
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# immediately *after* startup.
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#
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# Nifty hacks notwithstanding, this really isn't the right way to do
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# this. There ought to be an "import" mechanism we can use to resolve
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# dependencies between modules.
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#
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fovProp = nil;
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INIT = func {
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fovProp = props.globals.getNode("/sim/current-view/field-of-view");
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}
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settimer(INIT, 0);
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# Dynamically calculate limits so that it takes STEPS iterations to
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# traverse the whole range, the maximum FOV is fixed at 120 degrees,
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# and the minimum corresponds to normal maximum human visual acuity
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# (~1 arc minute of resolution, although apparently people vary widely
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# in this ability). Quick derivation of the math:
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#
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# mul^steps = max/min
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# steps * ln(mul) = ln(max/min)
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# mul = exp(ln(max/min) / steps)
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STEPS = 40;
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ACUITY = 1/60; # Maximum angle subtended by one pixel (== 1 arc minute)
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max = min = mul = 0;
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calcMul = func {
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max = 120; # Fixed at 120 degrees
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min = getprop("/sim/startup/xsize") * ACUITY;
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mul = math.exp(math.ln(max/min) / STEPS);
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}
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##
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# Hackish round-to-one-decimal-place function. Nasal needs a
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# sprintf() interface, or something similar...
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#
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format = func {
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val = int(arg[0]);
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frac = int(10 * (arg[0] - val) + 0.5);
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return val ~ "." ~ substr("" ~ frac, 0, 1);
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}
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##
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# Handler. Increase FOV by one step
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#
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increase = func {
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calcMul();
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val = fovProp.getValue() * mul;
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if(val == max) { return; }
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if(val > max) { val = max }
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fovProp.setDoubleValue(val);
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gui.popupTip("FOV: " ~ format(val));
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}
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##
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# Handler. Decrease FOV by one step
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#
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decrease = func {
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calcMul();
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val = fovProp.getValue() / mul;
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msg = "FOV: " ~ format(val);
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if(val < min) { msg = msg ~ " (overzoom)"; }
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fovProp.setDoubleValue(val);
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gui.popupTip(msg);
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}
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##
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# Handler. Reset view to default.
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#
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resetView = func {
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setprop("/sim/current-view/goal-heading-offset-deg",
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getprop("/sim/current-view/config/heading-offset-deg"));
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setprop("/sim/current-view/goal-pitch-offset-deg",
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getprop("/sim/current-view/config/pitch-offset-deg"));
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setprop("/sim/current-view/goal-roll-offset-deg",
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getprop("/sim/current-view/config/roll-offset-deg"));
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setprop("/sim/current-view/field-of-view",
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getprop("/sim/current-view/config/default-field-of-view-deg"))
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}
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##
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# Handler. Step to the next view.
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#
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stepView = func {
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curr = getprop("/sim/current-view/view-number");
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views = props.globals.getNode("/sim").getChildren("view");
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curr = curr + arg[0];
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if (curr < 0) { curr = size(views) - 1; }
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elsif(curr >= size(views)) { curr = 0; }
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setprop("/sim/current-view/view-number", curr);
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# And pop up a nice reminder
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gui.popupTip(views[curr].getNode("name").getValue());
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}
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##
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# Standard view "slew" rate, in degrees/sec.
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#
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VIEW_PAN_RATE = 60;
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##
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# Pans the view horizontally. The argument specifies a relative rate
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# (or number of "steps" -- same thing) to the standard rate.
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#
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panViewDir = func {
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controls.slewProp("/sim/current-view/goal-heading-offset-deg",
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arg[0] * VIEW_PAN_RATE);
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}
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##
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# Pans the view vertically. The argument specifies a relative rate
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# (or number of "steps" -- same thing) to the standard rate.
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#
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panViewPitch = func {
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controls.slewProp("/sim/current-view/goal-pitch-offset-deg",
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arg[0] * VIEW_PAN_RATE);
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}
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