Hello. I have been trying to learn Corona for a little while now.
I’m trying to make a game where a player push a small ball back and forth. When the ball fall past the right or left edge of the screen I want it to reappear at the opposite edge.
I’ve been trying to find an event that can detect when a ball fall past the edge, but I haven’t found any. I think I could just put up an invisible object at the edge, set it to a sensor and have it detect it, but I was wondering if there was a specific event for it. Also I am unsure how you would render it. I don’t want to just change the position of the ball, rather when half the ball is past the right edge, the other half appears on the left.
Is there a good way to do this in Corona? I’ve been trying to look trough the documentation but I haven’t found anything.
Screen wrapping is something you have to implement on your own.
SSK2 provides ready made code to do this:
https://roaminggamer.github.io/RGDocs/pages/SSK2/libraries/actions2/#scene-wrapping-scene
My (SSK2) implemention uses:
-
A rectangle object to act as the wrapping bounds/area. Usually hidden or alpha = 0.
- Why?
- Everyone knows how to make a rectangle object (newRect)
- You can show it, color it, etc. if you need debug feedback during development.
- Easy to manage. Just put it in a group and when the group is removed so is the wrapRect.
- Due to its nature, this means the wrapping rectangle size and placement can be arbitrary, thus making this technique easy and flexible.
-
The enterFrame listener
-
SSK2’s rectWrap function.
– Create a rectangle to act as our ‘wrapping bounds’ local wrapProxy = display.newRect( display.contentCenterX, display.contentCenterY, 300, 300 ) – Show it a little so we can see where the wrap should happen wrapProxy.alpha = 0.1 – Place a player in the center of the wrapProxy and give it a random velocity local player = display.newCirle( wrapProxy.x, wrapProxy.y, 20 ) physics:addBody( player ) player:setLinearVelocity( math.random( -100, 100), math.random( -100, 100) ) – Start an enter frame listener and test for wrapping each frame function player.enterFrame( self ) ssk.actions.scene.rectWrap( self, wrapProxy ) end Runtime:addEventListener( “enterFrame”, player )
Note: SSK2 also has a circle wrapper for a circular wrapping region if that is an effect you’re looking for.
Huh, that’s interesting. Thank you.
So far what I’ve done is I’ve made a couple of lines at the edges of my screen. Originally I wanted to use them for collision detection, then teleport the object to the opposite side of the screen once it went past them, but as I understand it you can’t update an objects .x and .y properties inside a collision event (I think I have to use a timer or something), so instead I just hooked it up tot the normal physics engine and have my ball bounce off them. (Makes it a bit more convenient to try things out if the ball doesn’t immediately disappear of screen)
I’ll check out this SSK2 thing 
Screen wrapping is something you have to implement on your own.
SSK2 provides ready made code to do this:
https://roaminggamer.github.io/RGDocs/pages/SSK2/libraries/actions2/#scene-wrapping-scene
My (SSK2) implemention uses:
-
A rectangle object to act as the wrapping bounds/area. Usually hidden or alpha = 0.
- Why?
- Everyone knows how to make a rectangle object (newRect)
- You can show it, color it, etc. if you need debug feedback during development.
- Easy to manage. Just put it in a group and when the group is removed so is the wrapRect.
- Due to its nature, this means the wrapping rectangle size and placement can be arbitrary, thus making this technique easy and flexible.
-
The enterFrame listener
-
SSK2’s rectWrap function.
– Create a rectangle to act as our ‘wrapping bounds’ local wrapProxy = display.newRect( display.contentCenterX, display.contentCenterY, 300, 300 ) – Show it a little so we can see where the wrap should happen wrapProxy.alpha = 0.1 – Place a player in the center of the wrapProxy and give it a random velocity local player = display.newCirle( wrapProxy.x, wrapProxy.y, 20 ) physics:addBody( player ) player:setLinearVelocity( math.random( -100, 100), math.random( -100, 100) ) – Start an enter frame listener and test for wrapping each frame function player.enterFrame( self ) ssk.actions.scene.rectWrap( self, wrapProxy ) end Runtime:addEventListener( “enterFrame”, player )
Note: SSK2 also has a circle wrapper for a circular wrapping region if that is an effect you’re looking for.
Huh, that’s interesting. Thank you.
So far what I’ve done is I’ve made a couple of lines at the edges of my screen. Originally I wanted to use them for collision detection, then teleport the object to the opposite side of the screen once it went past them, but as I understand it you can’t update an objects .x and .y properties inside a collision event (I think I have to use a timer or something), so instead I just hooked it up tot the normal physics engine and have my ball bounce off them. (Makes it a bit more convenient to try things out if the ball doesn’t immediately disappear of screen)
I’ll check out this SSK2 thing