overte/examples/gracefulControls.js

// Coefficient to use for linear drag.  Higher numbers will cause motion to
// slow down more quickly.
var DRAG_COEFFICIENT = 0.3;
var MAX_SPEED = 50.0;
var MAX_LOOK_SPEED = Math.PI * 2;
var ACCELERATION = 20;

var MOUSE_YAW_SCALE = -0.125;
var MOUSE_PITCH_SCALE = -0.125;
var MOUSE_SENSITIVITY = 1.0;

// Adjust this to change the mouse look damping behavior.  Keep it below 1.
var W = 0.9;

// Movement keys
var KEY_FORWARD = "w";
var KEY_BACKWARD = "s";
var KEY_LEFT = "a";
var KEY_RIGHT = "d";
var KEY_UP = "e";
var KEY_DOWN = "c";
var CAPTURED_KEYS = [KEY_FORWARD, KEY_BACKWARD, KEY_LEFT, KEY_RIGHT, KEY_UP, KEY_DOWN];

// Global Variables
var keys = {};
var velocity = { x: 0, y: 0, z: 0 };
var velocityVertical = 0;
var enabled = true;

var lastX = Window.getCursorPositionX();
var lastY = Window.getCursorPositionY();
var yawFromMouse = 0;
var pitchFromMouse = 0;
var maxAccel = Math.PI / 1;

var yawSpeed = 0;
var pitchSpeed = 0;

function keyPressEvent(event) {
    if (event.text == "ESC") {
        disable();
    } else if (event.text == " ") {
        if (Window.hasFocus()) {
            enable();
        }
    }
    keys[event.text] = true;
}

function keyReleaseEvent(event) {
    delete keys[event.text];
}

function update(dt) {
    var maxMove = 3.0 * dt;
    // print("Pos: " + yawFromMouse + ", " + pitchFromMouse);
    var targetVelocity = { x: 0, y: 0, z: 0 };
    var targetVelocityVertical = 0;

    if (keys[KEY_FORWARD]) {
        targetVelocity.z -= ACCELERATION * dt;
    }
    if (keys[KEY_LEFT]) {
        targetVelocity.x -= ACCELERATION * dt;
    }
    if (keys[KEY_BACKWARD]) {
        targetVelocity.z += ACCELERATION * dt;
    }
    if (keys[KEY_RIGHT]) {
        targetVelocity.x += ACCELERATION * dt;
    }
    if (keys[KEY_UP]) {
        targetVelocityVertical += ACCELERATION * dt;
    }
    if (keys[KEY_DOWN]) {
        targetVelocityVertical -= ACCELERATION * dt;
    }

    if (enabled && Window.hasFocus()) {
        var x = Window.getCursorPositionX();
        var y = Window.getCursorPositionY();

        yawFromMouse += ((x - lastX) * MOUSE_YAW_SCALE * MOUSE_SENSITIVITY);
        pitchFromMouse += ((y - lastY) * MOUSE_PITCH_SCALE * MOUSE_SENSITIVITY);
        pitchFromMouse = Math.max(-180, Math.min(180, pitchFromMouse));

        var newX = Window.innerWidth / 2;
        var newY = Window.innerHeight / 2;
        Window.setCursorPosition(newX, newY);

        lastX = newX;
        lastY = newY;
    }

    // Here we use a linear damping model - http://en.wikipedia.org/wiki/Damping#Linear_damping
    // Because we are using a critically damped model (no oscillation), ζ = 1 and
    // so we derive the formula: acceleration = -(2 * w0 * v) - (w0^2 * x)
    yawAccel = (W * W * yawFromMouse) - (2 * W * yawSpeed);
    pitchAccel = (W * W * pitchFromMouse) - (2 * W * pitchSpeed);

    yawSpeed += yawAccel * dt;
    var yawMove = yawSpeed * dt;
    var newOrientation = Quat.multiply(MyAvatar.orientation, Quat.fromVec3Degrees( { x: 0, y: yawMove, z: 0 } ));
    MyAvatar.orientation = newOrientation;
    yawFromMouse -= yawMove;

    pitchSpeed += pitchAccel * dt;
    var pitchMove = pitchSpeed * dt;
    var newPitch = MyAvatar.headPitch + pitchMove;
    MyAvatar.headPitch = newPitch;
    pitchFromMouse -= pitchMove;

    // If force isn't being applied in a direction, add drag;
    if (targetVelocity.x == 0) {
        targetVelocity.x -= (velocity.x * DRAG_COEFFICIENT * dt);
    }
    if (targetVelocity.z == 0) {
        targetVelocity.z -= (velocity.z * DRAG_COEFFICIENT * dt);
    }
    velocity = Vec3.sum(velocity, targetVelocity);

    velocity.x = Math.max(-MAX_SPEED, Math.min(MAX_SPEED, velocity.x));
    velocity.z = Math.max(-MAX_SPEED, Math.min(MAX_SPEED, velocity.z));
    var v = Quat.rotate(MyAvatar.headOrientation, velocity);

    if (velocityVertical == 0) {
        targetVelocityVertical -= (velocityVertical * DRAG_COEFFICIENT * dt);
    }
    velocityVertical += targetVelocityVertical;
    velocityVertical = Math.max(-MAX_SPEED, Math.min(MAX_SPEED, velocityVertical));
    v.y += velocityVertical;

    MyAvatar.setVelocity(v);
}

function vecToString(vec) {
    return vec.x + ", " + vec.y + ", " + vec.z;
}

function scriptEnding() {
    disable();
}

function enable() {
    enabled = true;
    lastX = Window.getCursorPositionX();
    lastY = Window.getCursorPositionY();
    for (var i = 0; i < CAPTURED_KEYS.length; i++) {
        Controller.captureKeyEvents({ text: CAPTURED_KEYS[i] });
    }
    Window.setCursorVisible(false);
    Script.update.connect(update);
}

function disable() {
    enabled = false;
    for (var i = 0; i < CAPTURED_KEYS.length; i++) {
        Controller.releaseKeyEvents({ text: CAPTURED_KEYS[i] });
    }
    Window.setCursorVisible(true);
    Script.update.disconnect(update);
}

Controller.keyPressEvent.connect(keyPressEvent);
Controller.keyReleaseEvent.connect(keyReleaseEvent);

Script.scriptEnding.connect(scriptEnding);