Sample FPS Player Script in New Engine
Entry posted by Josh ·
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Here is a script for a first-person player. All of this is actually working now. It's very interesting that physics, rendering, culling, and Lua game code are all executing at the same time on different threads. CPU usage in a simple scene and some physics is about 35% on a quad core processor, which is good.
I think the most interesting thing here is that to break the kinematic joint used to control an object the player picks up, you simply set the variable to nil. However, I did run into one problem with the garbage collector. If you do not call collectgarbage() after setting the joint variable to nil, the joint will not get deleted, and it will still affect the entity. This is not good. I got around this by placing a call to collectgarbage() immediately after getting rid of the joint, but I don't think I like that. I could just make the engine call the Lua garbage collector once before the world update and once before the world render. Originally, I thought Lua would be a big problem for VR applications but since the Lua game code gets its own thread, with a maximum execution time of about 16 milliseconds just for your game code, that is plenty of time to be wasteful with the GC, and I think we will be just fine even with high-performance VR games! Remember, the rendering thread runs at 90 hz but the game logic thread only runs at 60 or even 30 hz, so it's no big deal.
However, I am leaning towards adding a Destroy() function that frees everything it can from an object without actually deleting it.
Also note that window and context are global variables. There is no "current" window or context, so this code expect that these have been created in Lua or C++ and set as global variables.
Script.lookspeed=0.1--float Script.movespeed=3--float Script.maxcarrymass=10--float Script.throwforce=100--float function Script:Start() --Player physics if self.mass==0 then self.mass=70 end self:EnablePhysics(PHYSICS_PLAYER) self.collisiontype=COLLISION_PLAYER --Set up camera self.camera=CreateCamera(self:GetWorld()) local cx=Round(context:GetWidth()/2) local cy=Round(context:GetHeight()/2) window:HideMouse() window:SetMousePosition(cx,cy) self.camerarotation=self:GetRotation(true) end function Script:Update() --Mouse look local cx = Round(context:GetWidth()/2) local cy = Round(context:GetHeight()/2) local mousepos = window:GetMousePosition() window:SetMousePosition(cx,cy) local mx = mousepos.x - cx local my = mousepos.y - cy self.camerarotation.x = self.camerarotation.x + my * self.lookspeed self.camerarotation.y = self.camerarotation.y + mx * self.lookspeed self.camerarotation.x = Clamp(self.camerarotation.x,-90,90) self.camera:SetRotation(self.camerarotation,true) --Player movement local jump=0 if window:KeyDown(KEY_SPACE) then if self:GetAirborne()==false then jump=6 end end if self:GetAirborne() then jump = 0 end local move=0 if window:KeyDown(KEY_W) then move=move+1 end if window:KeyDown(KEY_S) then move=move-1 end local strafe=0 if window:KeyDown(KEY_D) then strafe=strafe+1 end if window:KeyDown(KEY_A) then strafe=strafe-1 end self:SetPlayerInput(self.camerarotation.y, move*self.movespeed, strafe*self.movespeed, jump, false,0,0,true,0) self.camera:SetPosition(self:GetPosition(true),true) self.camera:Translate(0,1.7,0,true) --Update carried object if self.carryjoint~=nil then --Update kinematic joint local position=TransformPoint(self.carryposition,self.camera,nil) local rotation=TransformRotation(self.carryrotation,self.camera,nil) self.carryjoint:SetTarget(position,rotation) --Throw if window:MouseHit(MOUSE_LEFT) then self.carryjoint.child:AddForce(TransformNormal(0,0,1,self.camera,nil)*self.throwforce) self.carryjoint.child:EnableGravity(true) self.carryjoint=nil collectgarbage() end end --Interact with environment if window:KeyHit(KEY_E) then if self.carryjoint~=nil then --Drop carried object self.carryjoint.child:EnableGravity(true) self.carryjoint=nil collectgarbage() else --Find new object to interact with local pickinfo = PickInfo() if self.camera:Pick(0,0,10,pickinfo,0,true,0) then local entity=pickinfo.entity if entity.Activate~=nil then --Activate the object entity:Activate(self) else --Pick it up if its light enough if entity.mass>0 and entity.mass<=self.maxcarrymass then if self.carryjoint~=nil then --Drop carried object self.carryjoint=nil collectgarbage() end local p=entity:GetPosition(true) entity:EnableGravity(false) self.carryjoint=CreateKinematicJoint(p.x,p.y,p.z,entity) self.carryposition=TransformPoint(entity:GetPosition(true),nil,self.camera) self.carryrotation=TransformRotation(entity:GetQuaternion(true),nil,self.camera) end end end end end end
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