Blender Gamekit Lua Constrain Plane Side Movement

Blender 3D game engine provides location constraint to limit object in a certain area. However this was not implemented in the Gamekit package. I have to do some scripting to get around it. So my plane will not fly out of the screen. Below is the script and red bits are my explanations. This is apart of series tutorials to create a 2d arcade plane game using Blender 3D and gamekit. Check this blog for more details.

-------BELOW IS OnInit.lua--------------

--Global variable

    --set touch move parameters

    Sensitivity = 0.005

    --invert = -1 -> is inverted

    Invert = 1

    Threshold=3.5

 -- Plane Constrain parameter

    Xmin = -0.87 --This is the left boundary, adjust if necessary

    Xmax = 0.87 --This is the right boundary, adjust if necessary

--this function is to stop plane moving cross the boundary

function xMoveFilter(limitSignal,oldX)

    if limitSignal == -1 and oldX > 0 then

        return oldX

    elseif limitSignal == -1 and oldX < 0 then

        return 0

    elseif limitSignal == 1 and oldX >0 then

        return 0

    elseif limitSignal ==1 and oldX <0 then

        return oldX

    end

        return 0

end

--this function is to determine whether plane is over the broundary

function XoverLimit(obj)

    local vec3 = obj:getPosition()

    if vec3.x < Xmin then

        return -1

    elseif vec3.x > Xmax then

        return 1

    else

        return 0

    end

end

--this function is for debug used to display plane position

function printPosition(obj)

    local vec3 = obj:getPosition()

    dPrintf("position x: " .. vec3.x)

    dPrintf("position y: " .. vec3.y)

    dPrintf("position z: " .. vec3.z)

    

end    

function velocityCap(v,vmax)

    if (v>vmax) then

        return vmax

    elseif (v < -vmax) then

        return -vmax

    else return v

    end

end

-------BELOW IS planeTouchMove.lua--------------

mouse=OgreKit.Mouse()
scene = OgreKit.getActiveScene()
play = scene:getObject("plane")
logicM = OgreKit.LogicManager()
myLogicObject = logicM:getObject("plane")
mySensor = myLogicObject:getSensor("Collision")
maxVelocity=0.08

mouse:capture()

--print current plane posistion on screen

printPosition(play)

--using threshold to filter out unwanted small touch movement

if ((mouse.xrel>Threshold or mouse.xrel<-Threshold)or(mouse.yrel>Threshold or mouse.yrel<-Threshold)and (not(play.touchBoundary))) then
      velocityY=velocityCap((mouse.yrel) * Sensitivity, maxVelocity)
      velocityX=velocityCap((mouse.xrel) * Sensitivity, maxVelocity)

      --check if plane over screen boundary 

      limitSignal = XoverLimit(play)

      --the X Y directions are swapped as the screen is in landscape

      if limitSignal==0  then

      --when plane is inside boundary

        play:translate(-velocityY* Invert,-velocityX * Invert,0)
      else

      --when plane touches boundary it can only move away from boundrary

        newY = xMoveFilter(limitSignal,-velocityY * Invert)
        play:translate(newY,-velocityX * Invert,0)
      end
end

    

Blender 3D Gamekit Plane Shoot Bullet IOS Android Tutorial

This is a follow up to the plane arcade game tutorial posted before. This time I added plane shooting bullet. For how to run it on real android device such as nexus 7, and ios devices, such as iPad. Please go to my youtube channel: http://www.youtube.com/user/hhhnzw. there are videos showing that.

1. if you continue from last tutorial first thing is to rename the Background image from Plane to background. it is confusing, as the aeroplane is also called plan.

2. Create an empty element. set its parent to plane. and move it to centre of the plane. and move down. so the Z axis' number is -0.1. Rename it as EmptyGunCentre.

3. Create a box, and scale smaller, it will become bullet. So pick a size as you think is proper. Rename it to bullet01.
4. Unwrap & export UV map from the box. and paint it to look like a bullet.
5.load the edited uv map in blender, and apply it to bullet element.
6. Put bullet on to layer 2, HIDDEN layer.
7. Pick the EmptyGunCentre, go to game logic editor to set it up like image below:

8. Turn on the hidden layer and pick the bullet. Then go to physics tab. Change type to dynamic. Change the min max velocity to 3.5. And lock Z axis.

9. Now pack the content in, and save the file. Test it on PC first. Then follow my other videos to run it on Android and IOS devices.

Blender file can be downloaded from link below:

https://docs.google.com/file/d/0B2dWucciRgDPZDNGMlBROW9sekE/edit?usp=sharing