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    Class Trail

    A Trail renderable that draws a fading, tapering ribbon behind a moving object. Points are sampled from a target or added manually, and rendered as connected quads with interpolated width and color.

    // simple single-color trail following a sprite
    const trail = new Trail({ target: player, color: "#44aaff", width: 20 });
    app.world.addChild(trail);

    // gradient trail following a sprite (fire effect)
    const trail = new Trail({
        target: player,
        width: 30,
        gradient: ["#ffff00", "#ff4400", "#ff000000"],
    });
    app.world.addChild(trail);

    // rainbow trail with custom width curve
    const trail = new Trail({
        target: player,
        width: 40,
        widthCurve: [1, 1, 0.8, 0.4, 0],
        gradient: ["#ff0000", "#ff8800", "#ffff00", "#00ff00", "#0088ff", "#8800ff00"],
    });
    app.world.addChild(trail);

    // manual mode (e.g. sword slash)
    const slash = new Trail({ width: 24, lifetime: 200, color: "#ffffff" });
    app.world.addChild(slash);
    // call each frame during the attack animation
    slash.addPoint(swordTip.x, swordTip.y);

    Renderable

    Hierarchy (View Summary)

    Index

    Constructors

    constructor

    Properties

    alpha alwaysUpdate ancestor anchorPoint autoTransform blendMode body currentTransform edges floating GUID indices isDirty isKinematic isPersistent lifetime mask maxPoints minDistance name onVisibilityChange points pos shader target type updateWhenPaused visibleInAllCameras widthCurve

    Accessors

    bottom centerX centerY depth height inViewport isFlippedX isFlippedY isFloating left parentApp right tint top width

    Methods

    addPoint angleTo centerOn clear clone contains containsRectangle copy distanceTo equals flipX flipY getAbsolutePosition getBounds getIndices getOpacity isConvex isFinite lookAt onCollision onDestroyEvent overlaps postDraw preDraw recalc resize rotate scale scaleV setOpacity setShape setSize setVertices shift to2d toIso toPolygon transform translate union updateBounds

    Constructors

    • Parameters

      • Optionaloptions: {
            blendMode?: string;
            color?: string | Color;
            gradient?: (string | Color | { color: string | Color; pos: number })[];
            length?: number;
            lifetime?: number;
            minDistance?: number;
            opacity?: number;
            target?: Vector2d | Renderable;
            width?: number;
            widthCurve?: number[];
        } = {}

        trail options

        • OptionalblendMode?: string

          blend mode

        • Optionalcolor?: string | Color

          single trail color. Ignored if gradient is set.

        • Optionalgradient?: (string | Color | { color: string | Color; pos: number })[]

          color gradient. Overrides color.

        • Optionallength?: number

          max number of points

        • Optionallifetime?: number

          point lifetime in ms

        • OptionalminDistance?: number

          min distance between samples in px

        • Optionalopacity?: number

          trail opacity (0.0–1.0)

        • Optionaltarget?: Vector2d | Renderable

          auto-follow target

        • Optionalwidth?: number

          max trail width in px

        • OptionalwidthCurve?: number[]

          width multiplier curve (0=head, 1=tail)

      Returns Trail

    Properties

    alpha: number

    Define the renderable opacity
    Set to zero if you do not wish an object to be drawn

    • Renderable#setOpacity
    • Renderable#getOpacity
    1.0
    alwaysUpdate: boolean

    Whether the renderable object will always update, even when outside of the viewport

    false
    ancestor: Container | Entity

    a reference to the parent object that contains this renderable

    undefined
    anchorPoint: ObservablePoint

    The anchor point is used for attachment behavior, and/or when applying transformations.
    The coordinate system places the origin at the top left corner of the frame (0, 0) and (1, 1) means the bottom-right corner

    a Renderable's anchor point defaults to (0.5,0.5), which corresponds to the center position.

    Note: Object created through Tiled will have their anchorPoint set to (0, 0) to match Tiled Level editor implementation. To specify a value through Tiled, use a json expression like json:{"x":0.5,"y":0.5}. 

    <0.5,0.5>
    autoTransform: boolean

    When enabled, an object container will automatically apply any defined transformation before calling the child draw method.

    true

    // enable "automatic" transformation when the object is activated
    onActivateEvent: function () {
        // reset the transformation matrix
        this.currentTransform.identity();
        // ensure the anchor point is the renderable center
        this.anchorPoint.set(0.5, 0.5);
        // enable auto transform
        this.autoTransform = true;
        ....
    }
    blendMode: string

    the blend mode to be applied to this renderable (see renderer setBlendMode for available blend mode)

    "normal"
    • CanvasRenderer#setBlendMode
    • WebGLRenderer#setBlendMode

    body

    body: Body

    the renderable physic body

    // define a new Player Class
     class PlayerEntity extends me.Sprite {
         // constructor
         constructor(x, y, settings) {
             // call the parent constructor
             super(x, y , settings);

             // define a basic walking animation
             this.addAnimation("walk",  [...]);
             // define a standing animation (using the first frame)
             this.addAnimation("stand",  [...]);
             // set the standing animation as default
             this.setCurrentAnimation("stand");

             // add a physic body
             this.body = new me.Body(this);
             // add a default collision shape
             this.body.addShape(new me.Rect(0, 0, this.width, this.height));
             // configure max speed, friction, and initial force to be applied
             this.body.setMaxVelocity(3, 15);
             this.body.setFriction(0.4, 0);
             this.body.force.set(3, 0);
             this.isKinematic = false;

             // set the display to follow our position on both axis
             app.viewport.follow(this.pos, app.viewport.AXIS.BOTH);
         }

         ...

    }
    currentTransform: Matrix3d

    the renderable transformation matrix (4x4). For standard 2D use, only the 2D components are used (rotate around Z, scale X/Y, translate X/Y). For 3D use (e.g. Mesh), the full 4x4 matrix supports rotation around any axis, 3D translation, and perspective projection. Use the rotate(), scale(), and translate() methods rather than modifying this directly.

    edges: Vector2d[]

    The edges here are the direction of the nth edge of the polygon, relative to the nth point. If you want to draw a given edge from the edge value, you must first translate to the position of the starting point.

    floating: boolean

    If true, this renderable will be rendered using screen coordinates, as opposed to world coordinates. Use this, for example, to define UI elements.

    false
    GUID: string

    (G)ame (U)nique (Id)entifier"
    a GUID will be allocated for any renderable object added
    to an object container (including the app.world container)

    indices: number[]

    a list of indices for all vertices composing this polygon

    isDirty: boolean

    when true the renderable will be redrawn during the next update cycle

    true
    isKinematic: boolean

    If true then physic collision and input events will not impact this renderable

    true
    isPersistent: boolean

    make the renderable object persistent over level changes

    false
    lifetime: number
    mask: Polygon | Rect | Ellipse | Line | RoundRect

    A mask limits rendering elements to the shape and position of the given mask object. So, if the renderable is larger than the mask, only the intersecting part of the renderable will be visible.

    undefined

    // apply a mask in the shape of a Star
    myNPCSprite.mask = new me.Polygon(myNPCSprite.width / 2, 0, [
       // draw a star
       {x: 0, y: 0},
       {x: 14, y: 30},
       {x: 47, y: 35},
       {x: 23, y: 57},
       {x: 44, y: 90},
       {x: 0, y: 62},
       {x: -44, y: 90},
       {x: -23, y: 57},
       {x: -47, y: 35},
       {x: -14, y: 30}
    ]);
    maxPoints: number
    minDistance: number
    name: string

    The name of the renderable

    ""
    onVisibilityChange: Function

    an event handler that is called when the renderable leave or enter a camera viewport

    undefined

    this.onVisibilityChange = function(inViewport) {
        if (inViewport === true) {
            console.log("object has entered the in a camera viewport!");
        }
    };
    points: Vector2d[]

    Array of points defining the Polygon
    Note: If you manually change points, you must call recalcafterwards so that the changes get applied correctly.

    pos: Vector2d

    origin point of the Polygon

    shader: any

    an optional shader, to be used instead of the default built-in one, when drawing this renderable (WebGL only). Use ShaderEffect for a custom fragment apply() function, or one of the built-in effect presets:

    Use GLShader for full control over vertex and fragment shaders. In Canvas mode, this property is ignored.

    undefined

    // apply a built-in effect
    mySprite.shader = new FlashEffect(renderer, { intensity: 1.0 });

    // custom shader effect
    mySprite.shader = new ShaderEffect(renderer, `
        vec4 apply(vec4 color, vec2 uv) {
            float gray = dot(color.rgb, vec3(0.299, 0.587, 0.114));
            return vec4(vec3(gray), color.a);
        }
    `);

    // to remove a custom shader
    mySprite.shader = undefined;
    target: Vector2d | Renderable | null
    type: string = "Rectangle"

    The shape type (used internally).

    updateWhenPaused: boolean

    Whether to update this object when the game is paused.

    false
    visibleInAllCameras: boolean

    If true, this floating renderable will be rendered by all cameras (e.g. background image layers). If false (default), floating elements are only rendered by the default camera (e.g. UI/HUD elements). Only applies to floating renderables in multi-camera setups.

    false
    widthCurve: number[]

    Accessors

    • get isFloating(): boolean

      Whether the renderable object is floating (i.e. used screen coordinates), or contained in a floating parent container

      Returns boolean

      Renderable#floating

    • get tint(): Color

      define a tint for this renderable. a (255, 255, 255) r, g, b value will remove the tint effect.

      Returns Color

      (255, 255, 255)

      // add a red tint to this renderable
      this.tint.setColor(255, 128, 128);
      // remove the tint
      this.tint.setColor(255, 255, 255);
    • set tint(value: Color): void

      Parameters

      • value: Color

      Returns void

    Methods

    • Returns true if the polygon contains the given point.
      (Note: it is highly recommended to first do a hit test on the corresponding
      bounding rect, as the function can be highly consuming with complex shapes)

      Parameters

      • x: number

        x coordinate or a vector point to check

      • y: number

        y coordinate

      Returns boolean

      True if the polygon contain the point, otherwise false

      if (polygon.contains(10, 10)) {
        // do something
      }
      // or
      if (polygon.contains(myVector2d)) {
        // do something
      }

    • Returns true if the polygon contains the given point.
      (Note: it is highly recommended to first do a hit test on the corresponding
      bounding rect, as the function can be highly consuming with complex shapes)

      Parameters

      Returns boolean

      True if the polygon contain the point, otherwise false

      if (polygon.contains(10, 10)) {
        // do something
      }
      // or
      if (polygon.contains(myVector2d)) {
        // do something
      }

    • Returns true if the vertices composing this polygon form a convex shape (vertices must be in clockwise order).

      Returns boolean | null

      true if the vertices are convex, false if not, null if not computable

    • onCollision callback, triggered in case of collision, when this renderable body is colliding with another one

      Returns boolean

      true if the object should respond to the collision (its position and velocity will be corrected)

      // collision handler
      onCollision(response) {
          if (response.b.body.collisionType === me.collision.types.ENEMY_OBJECT) {
              // makes the other object solid, by substracting the overlap vector to the current position
              this.pos.sub(response.overlapV);
              this.hurt();
              // not solid
              return false;
          }
          // Make the object solid
          return true;
      },

    • Rotate this renderable by the specified angle (in radians). When called with just an angle, rotates around the Z axis (2D rotation). When called with an angle and a Vector3d axis, rotates around that axis in 3D.

      Parameters

      • angle: number

        The angle to rotate (in radians)

      • Optionalv: any

        the axis to rotate around (defaults to Z axis for 2D)

      Returns Renderable

      Reference to this object for method chaining

    • scale the renderable around his anchor point. Scaling actually applies changes to the currentTransform member which is used by the renderer to scale the object when rendering. It does not scale the object itself. For example if the renderable is an image, the image.width and image.height properties are unaltered but the currentTransform member will be changed.

      Parameters

      • x: number

        a number representing the abscissa of the scaling vector.

      • Optionaly: number = x

        a number representing the ordinate of the scaling vector.

      • Optionalz: number = 1

        a number representing the depth of the scaling vector.

      Returns Renderable

      Reference to this object for method chaining

    • set new value to the Polygon

      Parameters

      • x: number

        position of the Polygon

      • y: number

        position of the Polygon

      • points: PolygonVertices | LineVertices

        array of vector or vertices defining the Polygon

      Returns Trail

      this instance for object chaining

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