Proper way to get entity acceleration?

[edgrt]

I was looking through code if I could find variable which could give me entity acceleration. I tried to calculate it by checking previous tick velocity (motionX/Y/Z) and current velocity in tick event but getting crash while loading game.

Im new in modding.

 

Vec3d prevmotion = new Vec3d(0,0,0);
	 @SubscribeEvent
	 public void onPlayerTick(TickEvent.PlayerTickEvent event) {
		 EntityPlayerSP player = mc.thePlayer;    	 		 
		 System.out.println((prevmotion.xCoord - player.motionX) + " "+ (prevmotion.yCoord - player.motionY)+" "+(prevmotion.zCoord - player.motionZ));		 
		 prevmotion = new Vec3d(player.motionX,player.motionY,player.motionZ);	 
	}
	

 

Error:

Description: Ticking player

java.lang.NullPointerException: Ticking player
	at aimbow.AimbowGui.onPlayerTick(AimbowGui.java:96)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_7_AimbowGui_onPlayerTick_PlayerTickEvent.invoke(.dynamic)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
	at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:185)
	at net.minecraftforge.fml.common.FMLCommonHandler.onPlayerPreTick(FMLCommonHandler.java:360)
	at net.minecraft.entity.player.EntityPlayer.onUpdate(EntityPlayer.java:215)
	at net.minecraft.entity.player.EntityPlayerMP.onUpdateEntity(EntityPlayerMP.java:345)
	at net.minecraft.network.NetHandlerPlayServer.update(NetHandlerPlayServer.java:176)
	at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher$1.update(NetworkDispatcher.java:218)
	at net.minecraft.network.NetworkManager.processReceivedPackets(NetworkManager.java:309)
	at net.minecraft.network.NetworkSystem.networkTick(NetworkSystem.java:197)
	at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:818)
	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:699)
	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:156)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:548)
	at java.lang.Thread.run(Unknown Source)

 

Edited April 12, 2017 by edgrt

[Draco18s]

> It crashed

> No crash posted

> No code posted

 

"Doctor! It hurts!"

[edgrt]

47 minutes ago, Draco18s said:

> It crashed

> No crash posted

> No code posted

 

"Doctor! It hurts!"

Thanks for curing me, doc.

[edgrt]

29 minutes ago, diesieben07 said:

PlayerTickEvent already gives the player to you. Don't try to access the Minecraft class (or other client-only classes) in common code.

Thanks, that was the problem. Now.. Im probably getting acceleration wrong way