[Martin]

Hi there,

our game has different layers which are implemented with the nice ParallaxItem component in the entities. Moreover, we would like to build the levels with the LevelEditor and thus have EntityBaseDraggable components like the following one.

import QtQuick 1.1
import VPlay 1.0
import Box2D 1.0

EntityBaseDraggable {
    id: obstacle
    entityType: "obstacle"

    width: size
    height: size

    property int size: 64
    property alias color: rectangle.color

    colliderComponent: collider
    selectionMouseArea.anchors.fill: rectangle
    gridSize: size
    colliderSize: width

    ParallaxItem {  // this seems to be a problem?! without it, everything works fine...
        ratio: 1.4

        Rectangle {
            id: rectangle
            color: "yellow"
            x: -obstacle.width / 2
            y: -obstacle.height / 2
            width: obstacle.width
            height: obstacle.height
        }

        BoxCollider {
            id: collider
            x: -obstacle.width / 2
            y: -obstacle.height / 2
            bodyType: Body.Static
        }
    }
}

Unfortunately, this does not work and the error message is not comprehensible [to me at least], i.e.,

file::/qml/VPlay/level/BuildEntityButton.qml:338: TypeError: Result of expression 'createdEntity' [undefined] is not an object.
file::/qml/VPlay/level/BuildEntityButton.qml:336: TypeError: Result of expression 'createdEntity' [undefined] is not an object.
BuildEntityButton: button MouseArea pressed, start dragging entity
file::/qml/VPlay/level/BuildEntityButton.qml:302:3: QML MouseArea: mapToItem() given argument "undefined" which is neither null nor an Item

If one removes ParallaxItem (or just replaces it by Item), everything seems to work just fine. So what is the problem and how can this be resolved?

Cheers, Martin

[Martin]

…and, to add another issue, specifying creationProperties as shown below results in the same error message as above, also in the otherwise working case without the ParallaxItem.

BuildEntityButton {
    id: obstaclebutton

    toCreateEntityType: "Obstacle.qml"
    creationProperties: { color: "green" }

    width: 50
    height: 50

    Rectangle {
        id: rectangle
        color: "green"
        anchors.fill: parent
    }
}

Could someone please also comment on this?

In general, it would be great to get more information in the error messages. If possible, they could be somewhat more meaningful and provide pointers to the exact location and cause of the error.

Cheers, Martin

[AlexFelgo Team]

Hi Martin,

 

Regarding your first post:

ratio: 1.4

the ratio must be set as Qt.point(x.x,x.x), for example:

ratio: Qt.point(0.8,1.0)

 

 

Regarding your second post:

creationProperties: { color: "green" }

should be:

creationProperties: { "color" : "green" }

There is obviously a mistake in the BuildEntityButton documentation, we will fix that.

 

Best Regards,

Alexander

[Martin]

Oops, my bad regarding the Qt.point… However, clearer error messages would help to find such errors. With the other suggested fix everything seems to work.

Spendid! Thanks a bunch!

Martin

[Martin]

Ok, there are still some issues with this. First of all, the ratio of such an EntityBaseDraggable with ParallaxItem has to be 1 initially and adjusted after it was created which is also the case for the position. Otherwise it will jump away from the mouse/finger when released. I figured out how to do this but interestingly, only the x component has to be modified, y is fine which is weird. In the respective BuildEntityButton, I have some code like this

    onEntityWasBuilt: {
        var obstacles = entityManager.getEntityArrayByType("obstacle");
        var o = obstacles[obstacles.length-1];

        var ratio = 1.5;
        var lx = levelContainer.x;      // position in the level
        var ly = levelContainer.y;
        var x1 = o.x + lx;              // split x
        var x2 = o.x - x1;

        o.x = x1/ratio + x2;            // x has to be adjusted according to parallax ratio
        o.y = o.y;                      // y not...?
        o.ratio = ratio;                // set parallax ratio
    }

Next thing is that I am not able to drag or remove such an entity once it is created. I guess you should be able to reproduce these problems with an EntityBaseDraggable as in post #5074.

Cheers, Martin

[AlexFelgo Team]

The reason you can’t drag and drop can be found (through a hopefully this time clearer error message 😛 ) in the output:

… EntityBaseDraggable.qml:449:3: QML MouseArea: Cannot anchor to an item that isn’t a parent or sibling.

selectionMouseArea.anchors.fill: xxx //parent or sibling else it can't anchor

 

Cheers, Alex

 

[Martin]

Ok, thanks for the hint. I clearly see the problem. However, the solution is not clear to me. Simply

selectionMouseArea.anchors.fill: parallaxitem

and assigning the ParallaxItem this id won’t do the trick. So how can the ParallaxItem with the Rectangle inside be made draggable?

Cheers, Martin

[AlexFelgo Team]

I still can’t quite understand what you trying to achieve, could you explain a little deeper what the outcome should be?

Anyway, with this code i have no problems moving around the entity, if you run it with enabled QML renderer then you can see that everything is in the right place.

import QtQuick 1.1
import VPlay 1.0
import Box2D 1.0

EntityBaseDraggable {
  id: obstacle
  entityType: "obstacle"

  width: size
  height: size

  property int size: 64
  property alias color: rectangle.color

  colliderComponent: collider
  selectionMouseArea.anchors.fill: item
  gridSize: size

  ParallaxItem {
    id: item
    //ratio: Qt.point(0.8,1.0)
    x: -width/2
    y: -height/2
    width: parent.width
    height: parent.height

    Rectangle {
      id: rectangle
      color: "grey"
      anchors.fill: parent
    }
  }

  BoxCollider {
    id: collider
    x: -width/2
    y: -height/2
    width: obstacle.width
    height: obstacle.height
    bodyType: Body.Static
  }
}

The BoxCollider must be a direct child of the EntitiyBase to work properly.

To help you any further i will need a little more information about the exact functionality that you want to achieve. 😉

 

Cheers, Alex

[Martin]

Thanks for the support. Our setup is as follows: A level is several times larger than the screen so that it is scrolled according to the movement of the player or directly with the joystick controller in the level editor. It consists of three layers. (1) background, i.e. the bottom z=0 with ratio 0.8, (2) obstacles, i.e. the center z=1 with ratio 1.0, (3) non-colliding objects which are “on top” z=2 with ratio 1.4. In the level editor, objects have to be places on layers (2) and (3).

I tried to construct a simple example of our setup since some code is worth a thousand words. Unfortunately, I seem to have introduced an error by this which I have not been able to track down yet. Here comes the main.qml which unfortunately crashes…

import VPlay 1.0
import QtQuick 1.1

GameWindow {
    activeScene: scene
    width: 960; height: 640
    focus: true
    Keys.forwardTo: controller

    EntityManager{
        id: entityManager
        entityContainer: levelContainer
        dynamicCreationEntityList: [Qt.resolvedUrl("Block.qml")]
    }

    TwoAxisController {
        id: controller
        inputActionsToKeyCode: {
            "up": Qt.Key_W,
                    "down": Qt.Key_S,
                    "left": Qt.Key_D,
                    "right": Qt.Key_A,
                    "fire": Qt.Key_Space
        }
    }

    MovementAnimation{
        target: levelContainer
        property: "pos"
        running: true
        property real scale: 200
        velocity: Qt.point(controller.xAxis*scale,controller.yAxis*scale)
    }

    Scene {
        id: scene
        width: 480
        height: 320

        LevelEditor {
            id: levelEditor
            toRemoveEntityTypes: ["obstacle"]
            toStoreEntityTypes: ["obstacle"]
        }

        // === LEVEL ===
        Item{
            id: levelContainer

            // === BACKGROUND ===
            ParallaxItem{
                id: background
                ratio: Qt.point(0.6,0.6)

                // some generated background...
                Grid{
                    rows: 10; columns: 10; spacing: 50
                    Repeater{
                        model: 100
                        Rectangle{
                            width: 100; height: 100
                            color: "grey"
                        }
                    }
                }
            }

            // === FOREGROUND ===
            ParallaxItem{
                id: levelgrid
                ratio: Qt.point(1,1)

                // some generated foreground...
                Grid{
                    rows: 10; columns: 10; spacing: 100
                    Repeater{
                        model: 100
                        Rectangle{
                            x: 100; y: 100
                            width: 50; height: 50
                            color: "red"
                        }
                    }
                }
            }

        }

//        BEButton{ }   // (*) we'll get to this later...
    }
}

Moreover, save the code of your last post to Box.qml.

The error message then is

EntityBase: entityDestroyed received, setting visible to false
destroy item in AbstractCCNodeManager: QObject(0x9b4b4c0) , nodeMgr: CCRectangleManager(0x9690118) 
the node to remove does not have a parent! that should never happen, because it means the root object wanted to be deleted! 
The program has unexpectedly finished.

What’s the matter here?

Cheers, Martin

[AlexFelgo Team]

You are using a Collider without defining a PhysicsWorld in your Scene, that’s the problem. Yeah we know, the error message doesn’t really point that out 😛 We will try to take care of that.

>> Moreover, save the code of your last post to Box.qml.
I guess it should be Block.qml

Cheers, Alex

[Martin]

Very well, you are right. And yes, it should be Block.qml.

Ok, so now activate the BEButton in main.qml which reads

import QtQuick 1.1
import VPlay 1.0

BuildEntityButton {
    id: bebutton
    width: 50; height: 50

    toCreateEntityType: "Block.qml"

    Rectangle {
        id: rectangle
        color: "yellow"
        anchors.fill: parent
    }
}

This now enables one to place Block entities on the level. However, they can’t be dragged once dropped.

Thanks in advance, Martin

[Martin]

Another observation: When the qmlrenderer is enabled, the ParallaxItem does not seem to have any effect whatsoever…

Best, Martin

[Martin]

Hi, could you (or anyone else) reproduce the described problem? Is it a bug or is there some mistake in my code?

Cheers, Martin

[Martin]

Another remark: When dragged initially, the entity moves according to the ratio of the ParallaxItem, i.e. at a different speed than the finger/mouse.

Do you have any suggestions for how to cope with these problems? Since this currently is a major problem for us, support is greatly appreciated.

Cheers, Martin

[AlexFelgo Team]

Hi Martin,

I’m currently trying to make it work, sorry for letting you wait quite some time.

Regarding the qml renderer, only our custom renderer can handle the parallax effect.

I will get come back to you as soon as i got news for you 😉

Cheers, Alex