LOVE2D中实现一个简单的摇杆

转自：http://blog.csdn.net/jkevin2016/article/details/52885137

local local_class = class() --这里用到云风的CLASS代码local gr=love.graphicslocal function getDistance (pointO,pointA )        distance = math.pow((pointO.x - pointA.x),2) + math.pow((pointO.y - pointA.y),2);        distance = math.sqrt(distance);        pointO,pointA=nil,nil    return distance;    endfunction local_class:ctor(bg,spr)    self.bg = bg    self.spr = spr     self.dir = 0    self.renge = 0    self.power = 0    self.w2 = self.bg:getWidth()/2    self.point = {x=0,y=0}    self.offset = {x=0,y=0}    self.press = falseendfunction local_class:update()endfunction local_class:setPoint(x,y)    self.point.x ,self.point.y = x,yendfunction local_class:draw()    gr.draw(bg,self.point.x,self.point.y,0,1,1,110,110)    gr.draw(center,self.point.x+self.offset.x,self.point.y+self.offset.y,0,1,1,48,48)endfunction local_class:touchpressed( id, x, y, dx, dy, pressure )    local radius  = self.w2    local dis = getDistance({x=x,y=y},self.point);      if dis < radius then        self.press = true        self.offset.x =  (x-self.point.x)        self.offset.y =  (y-self.point.y)    endendfunction local_class:touchreleased( id, x, y, dx, dy, pressure )    if self.press then         self.offset.x = 0        self.offset.y =  0    end    self.press = false    self.dir = 0endfunction local_class:touchmoved( id, x, y, dx, dy, pressure )    if self.press then         local radius  = self.w2        local dis = getDistance({x=x,y=y},self.point);          local angle = math.acos ( (x - self.point.x)/dis );        if dis>radius then            if ( y >  self.point.y ) then                self.offset.x =  radius*math.cos(angle)                self.offset.y = radius*math.sin(angle)             else                 self.offset.x = radius*math.cos(angle)                self.offset.y =  -(radius*math.sin(angle))            end        else            self.press = true            self.offset.x =  (x-self.point.x)            self.offset.y =  (y-self.point.y)        end        if dis > self.renge then             if (y > self.point.y) then                self:__checkDirection(angle);              else                  self:__checkDirection(-angle);              end        else             self.dir = 0        end         self.power = dis / radius    endendfunction local_class:getDirection()    return self.direndfunction local_class:__checkDirection(angle)    local dir = 0    local M_PI=math.pi    if (angle >= -M_PI/8.0 and angle <= M_PI/8.0)   then        dir = 6;      end      --[[右边走 -八分之派 到 八分之派--]]      if (angle >= -(M_PI/8.0) and angle <= M_PI/8.0)   then        dir = 6;      --[[右上方向 八分之派 到 八分之三派--]]      elseif( angle >= M_PI/8.0 and angle < 3*M_PI/8.0)   then        dir = 3;      --[[上方向 八分之三派 到 八分之五派--]]      elseif( angle >= 3*M_PI/8.0 and angle <= 5*M_PI/8.0)   then        dir = 2;      --[[左上方向 八分之5派 到 八分之七派--]]      elseif( angle > 5*M_PI/8.0 and angle < 7*M_PI/8.0)   then        dir = 1;      --[[左方向--]]      elseif( (angle >= 7*M_PI/8.0 and angle <= M_PI) or (angle <= -7*M_PI/8.0 and angle >= -M_PI))  then        dir = 4;      --[[左下方向--]]      elseif( angle > -7*M_PI/8.0 and angle < -5*M_PI/8.0)   then        dir = 7;      --[[下方向--]]      elseif( angle >= -5*M_PI/8.0 and angle <= -3*M_PI/8.0)  then        dir = 8;      --[[右下方向--]]      elseif( angle > -3*M_PI/8.0 and angle < -M_PI/8.0 ) then        dir = 9;      end      self.dir = direndreturn local_class

这里有个小例子
链接: http://pan.baidu.com/s/1boQcpVT 密码: drsm