The top bottom constraint is a bit tricky. As camera keeps moving with plane. I used camera as a reference to calcuate the top and bottom screen edge.
1. Get camera position
2. Calculate current top edge Y location
3. Calculate current bottom edge Y location
4. Compare with current plane location, and return signals, -1 as plane too low, 1 as plane too high, 0 for plane inside the screen
5. feed the signal and mouse movement to function edgeMoveFilter, which only permit plane move toward centre if it is on edge
The code is below and red marks are comments.
******Oninit.lua****************
--Global variable
--set touch move parameters
Sensitivity = 0.005
--invert = -1 -> is inverted
Invert = 1
Threshold=3.5
-- Plane Contrain
Xmin = -0.87
Xmax = 0.87
-- Plane Top Bottom Constrain
Ymin = -1.50
Ymax = 1.30
--filter movement so plane will only move towards center if touchs edge
function edgeMoveFilter(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
--check if over boundary on Y axis
function YoverLimit(obj,cameraObj)
local vec3 = obj:getPosition()
local cameraV = cameraObj:getLinearVelocity()
--get camero position
local cameraP = cameraObj:getPosition()
--calculate bottom edge ;ocation
local nextYmin = cameraP.y+Ymin
--calculate top edge location
local nextYmax = cameraP.y+Ymax
--check whether plane is on edge and return signals
if vec3.y < nextYmin then
return -1
elseif vec3.y > nextYmax then
return 1
else
return 0
end
end
--endNew-----------
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
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
******planeTouchMove.lua****************
mouse=OgreKit.Mouse()
scene = OgreKit.getActiveScene()
play = scene:getObject("plane")
--new--get camera objcet
camera = scene:getObject("Camera")
--end new---------------------------
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)
--new----------------------
--check if plane over screen boundary
limitSignalX = XoverLimit(play)
limitSignalY = YoverLimit(play,camera)
--the X Y directions are swap as the screen is in landscape
if limitSignalX==0 and limitSignalY == 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 = edgeMoveFilter(limitSignalX,-velocityY * Invert)
newX = edgeMoveFilter(limitSignalY,-velocityX * Invert)
play:translate(newY,newX,0)
end
--end new---------------------
end
