Ball

Last Updated On 2021-07-16

Version 8MinSDK 7Tutorial Video

A round 'sprite' that can be placed on a Canvas, where it can react to touches and drags, interact with other sprites (ImageSprites and other Balls) and the edge of the Canvas, and move according to its property values.

For example, to have a Ball move 4 pixels toward the top of a Canvas every 500 milliseconds (half second), you would set the Speed property to 4 [pixels], the Interval property to 500 [milliseconds], the Heading property to 90 [degrees], and the Enabled property to True.

The difference between a Ball and an ImageSprite is that the latter can get its appearance from an image file, while a Ball's appearance can be changed only by varying its PaintColor and Radius properties.

Properties

You can set the below properties in the UI part of the builder.

  • Enabled - it's a boolean value which is set to true by default.
  • Heading - it's a float value which is set to 0 by default.
  • Interval - it's a non negative integer value which is set to 100 by default.
  • OriginAtCenter - it's a boolean value which is set to false by default.
  • PaintColor - it's a color value which is set to &hff000000 by default.
  • Radius - it's a non negative integer value which is set to 5 by default.
  • Speed - it's a float value which is set to 0.0 by default.
  • Visible - it's a boolean value which is set to true by default.
  • X - it's a float value which is set to 0.0 by default.
  • Y - it's a float value which is set to 0.0 by default.
  • Z - it's a float value which is set to 1.0 by default.

Block Properties

You can set the below blocks properties in the blocks section of the builder.

Enabled

Controls whether the Ball moves and can be interacted with through collisions, dragging, touching, and flinging.


Heading

Returns the Ball's heading in degrees above the positive x-axis. Zero degrees is toward the right of the screen; 90 degrees is toward the top of the screen.


Interval

The interval in milliseconds at which the Ball's position is updated. For example, if the interval is 50 and the speed is 10, then every 50 milliseconds the sprite will move 10 pixels in the heading direction.


PaintColor

The color of the Ball.


Radius

The distance from the edge of the Ball to its center.


Speed

The number of pixels that the Ball should move every interval, if enabled.


Visible

Whether the Ball is visible.


X

The horizontal coordinate of the Ball, increasing as the Ball moves right. If the property OriginAtCenter is true, the coordinate is for the center of the Ball; otherwise, it is for the leftmost point of the Ball.


Y

The vertical coordinate of the Ball, increasing as the Ball moves down. If the property OriginAtCenter is true, the coordinate is for the center of the Ball; otherwise, it is for the uppermost point of the Ball.


Z

How the `Ball` should be layered relative to other



Methods

You can set the below method blocks in the blocks section of the builder.

Bounce

Makes the Ball bounce, as if off a wall. For normal bouncing, the edge argument should be the one returned by EdgeReached.

CollidingWith

Indicates whether a collision has been registered between this Ball and the passed sprite (Ball or ImageSprite).

MoveIntoBounds

Moves the Ball back in bounds if part of it extends out of bounds, having no effect otherwise. If the Ball is too wide to fit on the canvas, this aligns the left side of the Ball with the left side of the canvas. If the Ball is too tall to fit on the canvas, this aligns the top side of the Ball with the top side of the canvas.

MoveTo

Sets the x and y coordinates of the Ball. If CenterAtOrigin is true, the center of the Ball will be placed here. Otherwise, the top left edge of the Ball will be placed at the specified coordinates.

PointInDirection

Sets the heading of the Ball toward the point with the coordinates (x, y).

PointTowards

Turns the Ball to point towards a designated target sprite (Ball or ImageSprite). The new heading will be parallel to the line joining the centerpoints of the two sprites.


Events

You can set the below event blocks in the blocks section of the builder.

CollidedWith

Event handler called when two enabled sprites (

Dragged

Event handler called when a Ball is dragged. On all calls, the starting coordinates are where the screen was first touched, and the "current" coordinates describe the endpoint of the current line segment. On the first call within a given drag, the "previous" coordinates are the same as the starting coordinates; subsequently, they are the "current" coordinates from the prior call. Note that the Ball won't actually move anywhere in response to the Dragged event unless MoveTo is explicitly called. For smooth movement, each of its coordinates should be set to the sum of its initial value and the difference between its current and previous values.

EdgeReached

Event handler called when the Ball reaches an edge of the screen. If Bounce is then called with that edge, the Ball will appear to bounce off of the edge it reached. Edge here is represented as an integer that indicates one of eight directions north (1), northeast (2), east (3), southeast (4), south (-1), southwest (-2), west (-3), and northwest (-4).

Flung

Event handler called when a fling gesture (quick swipe) is made on an enabled Ball. This provides the x and y coordinates of the start of the fling (relative to the upper left of the canvas), the speed (pixels per millisecond), the heading (0-360 degrees), and the x and y velocity components of the fling's vector.

NoLongerCollidingWith

Event handler called when a pair of sprites (Balls and ImageSprites) are no longer colliding.

TouchDown

Event handler called when the user begins touching an enabled Ball (placing their finger on a Ball and leaving it there). This provides the x and y coordinates of the touch, relative to the upper left of the canvas.

TouchUp

Event handler called when the user stops touching an enabled Ball (lifting their finger after a TouchDown event). This provides the x and y coordinates of the touch, relative to the upper left of the canvas.

Touched

Event handler called when the user touches an enabled Ball and then immediately lifts their finger. The provided x and y coordinates are relative to the upper left of the canvas.