[GP]

hy,
We have an issue with the onContactEnd method. If I drag a shape and it collides with an other shape, everthing works fine but if i drag it first into a shape and then drag it into an other shape the onContactEnd method is called anyway but the dragged shape collides already with an other shape.

 

This is our used code:

fixture.onContactChanged: {
            if(!isPlaced) {
                boxImage.source = "../../img/box_notAllowed.png"; allowedToBuild = false;}}

        fixture.onEndContact:  {
            boxImage.source = "../../img/box.png"; allowedToBuild = true}

 

Also two screenshots:

First collide with platform: (everthing is fine)

http://i.imgur.com/ICJ0UdK.jpg

Then take new shape and drag it first into the platform and then up into the other shape (onContactEnd is called and you can place the shape)

http://i.imgur.com/9uyzQdG.jpg

[ChristianFelgo Team]

Hi GP, could you please post a full minimal QML demo that shows this problem in more detail?

Cheers, Chris

[GP]

Now here is a little demo project with the same issue:

Box.qml

EntityBaseDraggable {
    id: box
    entityType: "rectangle"
    entityId: "box"

    colliderComponent: boxCollider
    selectionMouseArea.anchors.fill: rect
    gridSize: 1
    height: 20
    width: 20
    dragOffset: Qt.point(0,0)
    allowedToBuild: true

    property alias sWidth: rect.width
    property alias sHeight: rect.height
    property bool isPlaced:false;

    showRectangleWhenBuildingNotAllowed: false


    Rectangle {
        id: rect
        width: 30
        height: 30
        color: "yellow"
    }


    BoxCollider {
        id: boxCollider
        anchors.fill:rect
        density:100

        friction: 1.6
        restitution: 0

        fixture.onBeginContact: {
            if(!isPlaced) {
                rect.color = "red"; allowedToBuild = false;}}
        fixture.onEndContact:  {
            rect.color = "yellow"; allowedToBuild = true}

    }
}

 

BoxPreview.qml

BuildEntityButton {

    id: ballPreview
    toCreateEntityType: "Box.qml"
    width: 20
    height: 20

    property int shapeWidth: 20
    property int shapeHeight: 20

    creationProperties: {

        "sWidth": shapeWidth,
        "sHeight": shapeHeight,
        "isPlaced":true
    }

    onEntityPressed: {

         createdEntity.isPlaced = false;

     }

    Rectangle {
        height: 20
        width: 20
        color: "yellow"
        anchors.fill: parent
    }

}

 

main.qml

import VPlay 1.0
import Box2D 1.0
import QtQuick 1.1

GameWindow {
    activeScene: scene
    // the size of the Window can be changed at runtime by pressing the number keys 1-6 with QML window active
    // the content of the logical scene size (480x320) gets scaled to the window size based on the scaleMode
    width: 960
    height: 640

    EntityManager {
        id: entityManager
        entityContainer: scene
    }
    
    Scene {
        id: scene

        Row {
            spacing: 5
            anchors {
                top: parent.top
                horizontalCenter: parent.horizontalCenter
            }

            BoxPreview{shapeHeight: 50; shapeWidth: 50}
            BoxPreview{shapeHeight: 50; shapeWidth: 50}
            BoxPreview{shapeHeight: 50; shapeWidth: 50}
        }

        Rectangle {
            width: 150
            height: 20
            color: "grey"

            x:50
            y:200

            BoxCollider {
                anchors.fill: parent
                bodyType: Body.Static
            }
        }

        PhysicsWorld {
            id: physicsWorld
            gravity.y: -9.81
            z: 10


            updatesPerSecondForPhysics: 60
            velocityIterations: 5
            positionIterations: 5
        }


    }
}

 

[Heini]

When i understand you right, you would like to place your entity, when it hasn´t any contact with another entity. I solved a similar problem by adding a counter, that gets incremented in the onBeginContact handler and decremented in the onContactEnd handler. When the counter reaches 0, you can place your entity.
Something like this:

BoxCollider{
....
  property int ContactCounter: 0

  onBeginContact:{
  contactCounter++
  }

  onContactEnd{
  --contactCounter;

  if (contactCounter===0)
	rect.color = "yellow"; allowedToBuild = true;
  }
}

Hope this is what you meaned.

[GP]

Hey guybrush,

 

thank your very much, that was exactly what i needed. I’ve tried the same thing with __collidingObstacles but this doesn’t work. Thanks again! 😉

[ChristianFelgo Team]

Great you found a solution! Thanks Guybrush for helping!