Canvas HUD

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C-130J basic HUD

Canvas - the FlightGear 2D drawing API
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RFC
Canvas Instancing Howto:New Canvas Execution Model Canvas SVG Canvas Popout Windows Canvas Scenery Overlays
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Canvas Map API (soon deprecated!) Canvas MapStructure Canvas MapStructure Layers MapStructure Snippets Canvas Radar Canvas Animation Framework (WIP) Canvas Plotting Framework (WIP) Canvas MFD Framework Canvas ND Framework Canvas PFD Framework Canvas MCDU Framework Canvas EFB Framework Canvas Wrappers Canvas Glass Cockpit Efforts
Tutorials
Howto:Getting started with Canvas Howto: Canvas Troubleshooting Howto:Adding a canvas to a GUI dialog (PUI!) Howto:Creating a Canvas GUI dialog file (New) Howto:Dynamic Liveries via Canvas (new) Howto:Creating a Canvas GUI Widget Howto:Add a 2D canvas instrument to your aircraft Howto:Parsing 2D Instruments using the Canvas Howto:Creating fullscreen Canvas applications Howto:Use SVG inside a Canvas Howto:Extend the Canvas SVG module Howto:Serializing a Canvas to SVG Howto:Canvas applications as Nasal submodules Howto:Using raster images and nested canvases Canvas HUD Howto:Project 3D to 2D coordinates on desktop canvas
Reference
Canvas Element Group Image Map Path Text Canvas Nasal API MessageBox Layout System Canvas GUI API Canvas draw library Event Handling
Related
Canvas Properties Unifying the 2D rendering backend via canvas Howto:Use a Camera View in an Instrument Howto:Extending Canvas to support rendering 3D models Howto:Extending Canvas to support MathGL
To be ported
Navigation display Map FGCanvas Canvas Nasal/JavaScript Subset
Deprecated by Canvas
Complex Glass Cockpit Avionics
(click on headings to toggle)

Moving the HUD to use the Canvas would be a great step from my point of view, since it and 2D panels (which I am happy to write the convert for!) are the last places besides the UI which make raw OpenGL calls, and hence would benefit from moving to the Canvas (and thus, to use OSG internally) — James Turner (Mon, 05 Nov 2012)

Rendering a basic HUD with a Canvas.

Note  For correct rendering (with Rembrandt deferred rendering) you need to register the HUD as transparent surface. <effect> <inherits-from>Effects/model-transparent</inherits-from> <!-- Replace 'HUD.l.canvas' with the object the canvas is placed on --> <object-name>HUD.l.canvas</object-name> </effect>

# ==============================================================================
# Head up display
# ==============================================================================

var pow2 = func(x) { return x * x; };
var vec_length = func(x, y) { return math.sqrt(pow2(x) + pow2(y)); };
var round0 = func(x) { return math.abs(x) > 0.01 ? x : 0; };
var clamp = func(x, min, max) { return x < min ? min : (x > max ? max : x); }

var HUD = {
  canvas_settings: {
    "name": "HUD",
    "size": [1024, 1024],
    "view": [480, 360],
    "mipmapping": 1
  },
  new: func(placement)
  {
    var m = {
      parents: [HUD],
      canvas: canvas.new(HUD.canvas_settings)
    };

    m.canvas.addPlacement(placement);
    m.canvas.setColorBackground(0.36, 1, 0.3, 0.02);
    
    m.root =
      m.canvas.createGroup()
              .setScale(1, 1/math.cos(25 * math.pi/180))
              .setTranslation(240, 180)
              .set("font", "LiberationFonts/LiberationMono-Regular.ttf")
              .setDouble("character-size", 18)
              .setDouble("character-aspect-ration", 0.9)
              .set("stroke", "rgba(0,255,0,0.9)");
    m.text =
      m.root.createChild("group")
            .set("fill", "rgba(0,255,0,0.9)");

    # Heading
    m.hdg =
      m.text.createChild("text")
            .setDrawMode(3)
            .setPadding(2)
            .setAlignment("center-top")
            .setTranslation(0, -140);

    # Airspeed
    m.airspeed =
      m.text.createChild("text")
            .setAlignment("right-center")
            .setTranslation(-180, 0);
    
    # Groundspeed
    m.groundspeed =
      m.text.createChild("text")
            .setAlignment("left-center")
            .setTranslation(-220, 90);
    
    # Vertical speed
    m.vertical_speed =
      m.text.createChild("text")
            .setFontSize(10, 0.9)
            .setAlignment("right-center")
            .setTranslation(205, 50);
    
    # Radar altidude
    m.rad_alt =
      m.text.createChild("text")
            .setAlignment("right-center")
            .setTranslation(220, 70);

    # Waterline / Pitch indicator
      m.root.createChild("path")
            .moveTo(-24, 0)
            .horizTo(-8)
            .lineTo(-4, 6)
            .lineTo(0, 0)
            .lineTo(4, 6)
            .lineTo(8, 0)
            .horizTo(24)
            .setStrokeLineWidth(0.9);
    
    # Flightpath/Velocity vector
    m.fpv = m.root.createChild("group", "FPV");
    m.fpv.createChild("path")
         .moveTo(8, 0)
         .arcSmallCCW(8, 8, 0, -16, 0)
         .arcSmallCCW(8, 8, 0,  16, 0)
         .moveTo(-8, 0)
         .horiz(-16)
         .moveTo(8, 0)
         .horiz(16)
         .setStrokeLineWidth(0.9);

    # Energy/Acceleration cues
    m.energy_cue =
      m.fpv.createChild("path")
           .setStrokeLineWidth(1);

    m.acc =
      m.fpv.createChild("path")
           .setStrokeLineWidth(1);
    
    # Horizon
    m.horizon_group = m.root.createChild("group");
    m.h_trans = m.horizon_group.createTransform();
    m.h_rot   = m.horizon_group.createTransform();
    
    # Pitch lines
    for(var i = 5; i <= 10; i += 5)
    {
      m.horizon_group.createChild("path")
                     .moveTo(24, -i * 18)
                     .horiz(48)
                     .vert(7)
                     .moveTo(-24, -i * 18)
                     .horiz(-48)
                     .vert(7)
                     .setStrokeLineWidth(1.5);
    }
    
    # Horizon line
    m.horizon_group.createChild("path")
                   .moveTo(-500, 0)
                   .horizTo(500)
                   .setStrokeLineWidth(1.5);

    m.input = {
      pitch:      "/orientation/pitch-deg",
      roll:       "/orientation/roll-deg",
      hdg:        "/orientation/heading-deg",
      speed_n:    "velocities/speed-north-fps",
      speed_e:    "velocities/speed-east-fps",
      speed_d:    "velocities/speed-down-fps",
      alpha:      "/orientation/alpha-deg",
      beta:       "/orientation/side-slip-deg",
      ias:        "/velocities/airspeed-kt",
      gs:         "/velocities/groundspeed-kt",
      vs:         "/velocities/vertical-speed-fps",
      rad_alt:    "/instrumentation/radar-altimeter/radar-altitude-ft",
      wow_nlg:    "/gear/gear[4]/wow",
      airspeed:   "/velocities/airspeed-kt",
      target_spd: "/autopilot/settings/target-speed-kt",
      acc:        "/fdm/jsbsim/accelerations/udot-ft_sec2"
    };
    
    foreach(var name; keys(m.input))
      m.input[name] = props.globals.getNode(m.input[name], 1);
    
    return m;
  },
  update: func()
  {
    me.airspeed.setText(sprintf("%d", me.input.ias.getValue()));
    me.groundspeed.setText(sprintf("G %3d", me.input.gs.getValue()));
    me.vertical_speed.setText(sprintf("%.1f", me.input.vs.getValue() * 60.0 / 1000));
    
    var rad_alt = me.input.rad_alt.getValue();
    if( rad_alt and rad_alt < 5000 ) # Only show below 5000AGL
      rad_alt = sprintf("R %4d", rad_alt);
    else
      rad_alt = nil;
    me.rad_alt.setText(rad_alt);
    
    me.hdg.setText(sprintf("%03d", me.input.hdg.getValue()));
    me.h_trans.setTranslation(0, 18 * me.input.pitch.getValue());
    
    var rot = -me.input.roll.getValue() * math.pi / 180.0;
    me.h_rot.setRotation(rot);
    
    # flight path vector (FPV)
    var vel_gx = me.input.speed_n.getValue();
    var vel_gy = me.input.speed_e.getValue();
    var vel_gz = me.input.speed_d.getValue();
    
    var yaw = me.input.hdg.getValue() * math.pi / 180.0;
    var roll = me.input.roll.getValue() * math.pi / 180.0;
    var pitch = me.input.pitch.getValue() * math.pi / 180.0;
    
    var sy = math.sin(yaw);   var cy = math.cos(yaw);
    var sr = math.sin(roll);  var cr = math.cos(roll);
    var sp = math.sin(pitch); var cp = math.cos(pitch);

    var vel_bx = vel_gx * cy * cp
               + vel_gy * sy * cp
               + vel_gz * -sp;
    var vel_by = vel_gx * (cy * sp * sr - sy * cr)
               + vel_gy * (sy * sp * sr + cy * cr)
               + vel_gz * cp * sr;
    var vel_bz = vel_gx * (cy * sp * cr + sy * sr)
               + vel_gy * (sy * sp * cr - cy * sr)
               + vel_gz * cp * cr;

    var dir_y = math.atan2(round0(vel_bz), math.max(vel_bx, 0.01)) * 180.0 / math.pi;
    var dir_x  = math.atan2(round0(vel_by), math.max(vel_bx, 0.01)) * 180.0 / math.pi;

    me.fpv.setTranslation(dir_x * 18, dir_y * 18);

    var speed_error = 0;
    if( me.input.target_spd.getValue() != nil )
      speed_error = 4 * clamp(
        me.input.target_spd.getValue() - me.input.airspeed.getValue(),
        -15, 15
      );
    
    me.energy_cue.reset();
#    if( math.abs(speed_error) > 3 )
      me.energy_cue.moveTo(-22, 0)
                   .vert(speed_error)
                   .horiz(3)
                   .vertTo(0);
    
    var acc = me.input.acc.getValue() or 0;
    me.acc.reset()
          .moveTo(-34, -acc * 5 - 4)
          .line(8, 4)
          .line(-8, 4);

    settimer(func me.update(), 0);
  }
};

var init = setlistener("/sim/signals/fdm-initialized", func() {
  removelistener(init); # only call once
  var hud_pilot = HUD.new({"node": "HUD.l.canvas"});
  hud_pilot.update();
#  var hud_copilot = HUD.new({"node": "HUD.l.canvas.001"});
#  hud_copilot.update();
});