我遇到的问题很简单。我在屏幕中央有一个对象，然后是一个围绕该对象运行的圆圈。我想要做的是让对象围绕对象运行，当用户触摸屏幕时，它将围绕对象运行并停止面向用户点击屏幕的位置。
我在尝试完成这项工作时遇到了巨大的困难。但我想我会做的是尝试从物体的中心画一条线到使用点击的地方，然后围绕地球运行的球撞到它将停止的线（很简单）。我遇到的问题是线对象（在混合模式下查看时）更像是一个矩形，然后它是一条线（在物理引擎中，所以这与我的预期结果相混淆。有没有人知道我做错了什么在这里？或者电晕是如何处理这个的？以及如何解决它？或者任何其他解决方案也可以很好地工作。
physics = require("physics") ; physics.start() ; physics.setGravity( 0,0 ) ;
physics.setDrawMode( "hybrid" )
display.setStatusBar( display.HiddenStatusBar )
math.randomseed( os.time() )
--set up some references and other variables
local ox, oy = math.abs(display.screenOriginX), math.abs(display.screenOriginY)
local cw, ch = display.contentWidth, display.contentHeight
--set up collision filters
local screenFilter = { categoryBits=2, maskBits=1 }
local objFilter = { categoryBits=1, maskBits=14 }
local fieldFilter = { categoryBits=4, maskBits=1 }
local magnetFilter = { categoryBits=8, maskBits=1 }
--set initial magnet pull
local magnetPull = 0.85
--set up world and background
local screenBounds = display.newRect( -ox, -oy, display.contentWidth+ox+ox, display.contentHeight+oy+oy )
screenBounds.name = "screenBounds"
screenBounds.isVisible = false ; physics.addBody( screenBounds, "static", { isSensor=true, filter=screenFilter } )
local function newPositionVelocity( object )
local math_random = math.random
local side = math_random( 1,4 ) ; local posX ; local posY ; local velX ; local velY
if ( side == 1 or side == 3 ) then
posX = math_random(0,display.pixelHeight)
velX = math_random( -10,10 ) * 5
if ( side == 1 ) then posY = -oy-40 ; velY = math_random( 8,18 ) * 16
else posY = display.contentHeight+oy+40 ; velY = math_random( 8,16 ) * -16
end
else
posY = math_random(0,display.pixelWidth)
velY = math_random( -10,10 ) * 5
if ( side == 4 ) then posX = -ox-40 ; velX = math_random( 8,16 ) * 16
else posX = display.contentWidth+ox+40 ; velX = math_random( 8,16 ) * -16
end
end
object.x = posX ; object.y = posY
object:setLinearVelocity( velX, velY )
object.angularVelocity = math_random( -3,3 ) * 40
object.alpha = 1
end
require( "repeller");
local rect = createRepeller(15, "rect",cw/2, cw/2);
local function objectCollide( self, event )
local otherName = event.other.name;
local function onDelay( event )
local action = ""
if ( event.source ) then action = event.source.action; timer.cancel( event.source ) end
if ( action == "makeJoint" ) then
self.hasJoint = true
self.touchJoint = physics.newJoint( "touch", self, self.x, self.y )
self.touchJoint.frequency = magnetPull
self.touchJoint.dampingRatio = 0.0
self.touchJoint:setTarget( 512, 384 )
elseif ( action == "leftField" ) then
self.hasJoint = false ; self.touchJoint:removeSelf() ; self.touchJoint = nil
else
if ( self.hasJoint == true ) then self.hasJoint = false ; self.touchJoint:removeSelf() ; self.touchJoint = nil end
newPositionVelocity( self )
end
end
if ( event.phase == "ended" and otherName == "screenBounds" ) then
local tr = timer.performWithDelay( 10, onDelay ) ; tr.action = "leftScreen"
elseif ( event.phase == "began" and otherName == "rect" ) then
transition.to( self, { time=400, alpha=0, onComplete=onDelay } )
elseif ( event.phase == "began" and otherName == "field" and self.hasJoint == false ) then
local tr = timer.performWithDelay( 10, onDelay ) ; tr.action = "makeJoint"
elseif ( event.phase == "ended" and otherName == "field" and self.hasJoint == true ) then
local tr = timer.performWithDelay( 10, onDelay ) ; tr.action = "leftField"
end
end
local function setupWorld()
for i=1, 0 do
local obj = display.newCircle(0,0, 12 )
physics.addBody( obj, "dynamic", { bounce=.3, radius=12, density = 0.0 --[[,filter=objFilter]] } )
obj. isBullet = true;
newPositionVelocity( obj )
obj.hasJoint = false;
obj.name = "ball";
obj.collision = objectCollide ; obj:addEventListener( "collision", obj )
end
local field = display.newCircle(cw/2, ch/2, 320);
field.alpha = 0.2;
field.name = "field";
field.x = display.contentCenterX ; field.y = display.contentCenterY;
physics.addBody( field, "static", { isSensor=true, radius=320, filter=fieldFilter });
magnet = display.newCircle(cw/2, ch/2, 40 )
magnet.name = "magnet"
magnet.x = display.contentCenterX ; magnet.y = display.contentCenterY
physics.addBody( magnet, "static", { bounce=0, radius=40, filter=magnetFilter } )
end
setupWorld()
deg = 0.0;
local prevPosY = 0
local line = display.newLine(cw/2,ch/2,cw/2,ch/2);
local function onTouch(event)
if line ~= nil then
line:removeSelf();
end
if event.phase == "began" then
prevPosY = event.y
end
if(event.y >= prevPosY) then
myJoint.motorSpeed = -(1.5 * prevPosY - event.y);
elseif(event.y <= prevPosY) then
myJoint.motorSpeed = 1.5 * prevPosY - event.y;
end
if(prevPosY - event.y == 0) then
--myJoint.motorSpeed = 0;
end
prevPosY = event.y;
line = display.newLine(cw/2,ch/2,event.x, event.y);
line.width= 1;
line.name = "line";
physics.addBody(line, { isSensor = true })
local function lineCol(self, event)
if (event.other.name=="rect") then
myJoint.motorSpeed = 0;
print(event.other.name, event.name);
--rect:removeSelf();
end
end
line.collision = lineCol;
line:addEventListener("collision", line);
end
line = display.newLine(cw/2,ch/2, 200 , 250);
line.width= 1;
line.name = "line";
physics.addBody(line, { isSensor = true, shape=line })
--Runtime:addEventListener( "collision", lineCol)
physics.addBody(rect,"dynamic", {bounce = 0, density = 0})
myJoint = physics.newJoint( "pivot", rect, magnet, cw/2, ch/2);
myJoint.isMotorEnabled = true;
myJoint.motorSpeed = 0;
myJoint.maxMotorTorque = 100;
Runtime:addEventListener("touch", onTouch);
和我的“repeller.lua”
function createRepeller(size, name, locX, locY)
local rep = display.newCircle(locX,locY, size);
rep.name = name;
return rep;
end