preparation for train coupling

src/main/java/com/hbm/entity/train/EntityRailCarBase.java

@@ -20,6 +20,7 @@ public abstract class EntityRailCarBase extends Entity {
 
 	public boolean isOnRail = true;
 	private int turnProgress;
+	/* Clientside position that should be approached with smooth interpolation */
 	private double trainX;
 	private double trainY;
 	private double trainZ;
@@ -29,6 +30,16 @@ public abstract class EntityRailCarBase extends Entity {
 	@SideOnly(Side.CLIENT) private double velocityX;
 	@SideOnly(Side.CLIENT) private double velocityY;
 	@SideOnly(Side.CLIENT) private double velocityZ;
+	/* "Actual" position with offset directly between the front and back pos, won't match the standard position on curves */
+	public double lastRenderX;
+	public double lastRenderY;
+	public double lastRenderZ;
+	public double renderX;
+	public double renderY;
+	public double renderZ;
+
+	public EntityRailCarBase coupledFront;
+	public EntityRailCarBase coupledBack;
 	
 	public boolean initDummies = false;
 	public BoundingBoxDummyEntity[] dummies = new BoundingBoxDummyEntity[0];
@@ -41,21 +52,15 @@ public abstract class EntityRailCarBase extends Entity {
 	@Override protected void readEntityFromNBT(NBTTagCompound nbt) { }
 	@Override protected void writeEntityToNBT(NBTTagCompound nbt) { }
 	
-	/*@Override
-	public boolean canBePushed() {
-		return true;
-	}
-
-	@Override
-	public boolean canBeCollidedWith() {
-		return !this.isDead;
-	}*/
-	
 	@Override
 	public void onUpdate() {
 
 		if(this.worldObj.isRemote) {
 
+			this.prevPosX = this.posX;
+			this.prevPosY = this.posY;
+			this.prevPosZ = this.posZ;
+			
 			if(this.turnProgress > 0) {
 				this.prevRotationYaw = this.rotationYaw;
 				double x = this.posX + (this.trainX - this.posX) / (double) this.turnProgress;
@@ -71,6 +76,21 @@ public abstract class EntityRailCarBase extends Entity {
 				this.setPosition(this.posX, this.posY, this.posZ);
 				this.setRotation(this.rotationYaw, this.rotationPitch);
 			}
+
+			BlockPos anchor = this.getCurentAnchorPos();
+			Vec3 frontPos = getRelPosAlongRail(anchor, this.getLengthSpan());
+			Vec3 backPos = getRelPosAlongRail(anchor, -this.getLengthSpan());
+
+			this.lastRenderX = this.renderX;
+			this.lastRenderY = this.renderY;
+			this.lastRenderZ = this.renderZ;
+			
+			if(frontPos != null && backPos != null) {
+				this.renderX = (frontPos.xCoord + backPos.xCoord) / 2D;
+				this.renderY = (frontPos.yCoord + backPos.yCoord) / 2D;
+				this.renderZ = (frontPos.zCoord + backPos.zCoord) / 2D;
+			}
+			
 		} else {
 			
 			DummyConfig[] definitions = this.getDummies();
@@ -109,6 +129,9 @@ public abstract class EntityRailCarBase extends Entity {
 					this.derail();
 					return;
 				} else {
+					this.renderX = (frontPos.xCoord + backPos.xCoord) / 2D;
+					this.renderY = (frontPos.yCoord + backPos.yCoord) / 2D;
+					this.renderZ = (frontPos.zCoord + backPos.zCoord) / 2D;
 					this.prevRotationYaw = this.rotationYaw;
 					this.rotationYaw = this.movementYaw = generateYaw(frontPos, backPos);
 					this.motionX = this.rotationYaw / 360D; // hijacking this crap for easy syncing
@@ -121,9 +144,9 @@ public abstract class EntityRailCarBase extends Entity {
 				BoundingBoxDummyEntity dummy = dummies[i];
 				Vec3 rot = Vec3.createVectorHelper(def.offset.xCoord, def.offset.yCoord, def.offset.zCoord);
 				rot.rotateAroundY((float) (-this.rotationYaw * Math.PI / 180));
-				double x = posX + rot.xCoord;
+				double x = renderX + rot.xCoord;
-				double y = posY + rot.yCoord;
+				double y = renderY + rot.yCoord;
-				double z = posZ + rot.zCoord;
+				double z = renderZ + rot.zCoord;
 				dummy.setSize(def.width, def.height); // TEMP
 				dummy.setPosition(x, y, z);
 			}
@@ -319,4 +342,17 @@ public abstract class EntityRailCarBase extends Entity {
 			this.offset = offset;
 		}
 	}
+	
+	public static enum TrainCoupling {
+		FRONT,
+		BACK
+	}
+	
+	public Vec3 getCouplingPos(TrainCoupling coupling) {
+		return null;
+	}
+	
+	public EntityRailCarBase getCoupledTo(TrainCoupling coupling) {
+		return coupling == TrainCoupling.FRONT ? this.coupledFront : coupling == TrainCoupling.BACK ? this.coupledBack : null;
+	}
 }

src/main/java/com/hbm/entity/train/EntityRailCarRidable.java

@@ -90,8 +90,8 @@ public abstract class EntityRailCarRidable extends EntityRailCarCargo {
 			if(passengerSeats[i] != null) continue;
 			
 			seat.rotateAroundY((float) (-this.rotationYaw * Math.PI / 180));
-			double x = posX + seat.xCoord;
+			double x = renderX + seat.xCoord;
-			double z = posZ + seat.zCoord;
+			double z = renderZ + seat.zCoord;
 
 			double deltaX = player.posX - x;
 			double deltaZ = player.posZ - z;
@@ -108,8 +108,8 @@ public abstract class EntityRailCarRidable extends EntityRailCarCargo {
 		if(this.riddenByEntity == null) {
 			Vec3 seat = getRiderSeatPosition();
 			seat.rotateAroundY((float) (-this.rotationYaw * Math.PI / 180));
-			double x = posX + seat.xCoord;
+			double x = renderX + seat.xCoord;
-			double z = posZ + seat.zCoord;
+			double z = renderZ + seat.zCoord;
 
 			double deltaX = player.posX - x;
 			double deltaZ = player.posZ - z;
@@ -131,9 +131,9 @@ public abstract class EntityRailCarRidable extends EntityRailCarCargo {
 			SeatDummyEntity dummySeat = new SeatDummyEntity(worldObj, this);
 			Vec3 passengerSeat = this.getPassengerSeats()[nearestSeat];
 			passengerSeat.rotateAroundY((float) (-this.rotationYaw * Math.PI / 180));
-			double x = posX + passengerSeat.xCoord;
+			double x = renderX + passengerSeat.xCoord;
-			double y = posY + passengerSeat.yCoord;
+			double y = renderY + passengerSeat.yCoord;
-			double z = posZ + passengerSeat.zCoord;
+			double z = renderZ + passengerSeat.zCoord;
 			dummySeat.setPosition(x, y - 1, z);
 			passengerSeats[nearestSeat] = dummySeat;
 			worldObj.spawnEntityInWorld(dummySeat);
@@ -160,9 +160,9 @@ public abstract class EntityRailCarRidable extends EntityRailCarCargo {
 					} else {
 						Vec3 rot = seats[i];
 						rot.rotateAroundY((float) (-this.rotationYaw * Math.PI / 180));
-						double x = posX + rot.xCoord;
+						double x = renderX + rot.xCoord;
-						double y = posY + rot.yCoord;
+						double y = renderY + rot.yCoord;
-						double z = posZ + rot.zCoord;
+						double z = renderZ + rot.zCoord;
 						seat.setPosition(x, y - 1, z);
 					}
 				}
@@ -177,7 +177,7 @@ public abstract class EntityRailCarRidable extends EntityRailCarCargo {
 		offset.rotateAroundY((float) (-this.rotationYaw * Math.PI / 180));
 		
 		if(this.riddenByEntity != null) {
-			this.riddenByEntity.setPosition(this.posX + offset.xCoord, this.posY + offset.yCoord, this.posZ + offset.zCoord);
+			this.riddenByEntity.setPosition(this.renderX + offset.xCoord, this.renderY + offset.yCoord, this.renderZ + offset.zCoord);
 		}
 	}
 

src/main/java/com/hbm/render/entity/item/RenderTrainCargoTram.java

@@ -2,6 +2,7 @@ package com.hbm.render.entity.item;
 
 import org.lwjgl.opengl.GL11;
 
+import com.hbm.entity.train.EntityRailCarBase;
 import com.hbm.main.ResourceManager;
 
 import net.minecraft.client.renderer.entity.Render;
@@ -13,6 +14,18 @@ public class RenderTrainCargoTram extends Render {
 	@Override
 	public void doRender(Entity entity, double x, double y, double z, float swing, float interp) {
 		GL11.glPushMatrix();
+		
+		EntityRailCarBase train = (EntityRailCarBase) entity;
+		double iX = train.prevPosX + (train.posX - train.prevPosX) * interp;
+		double iY = train.prevPosY + (train.posY - train.prevPosY) * interp;
+		double iZ = train.prevPosZ + (train.posZ - train.prevPosZ) * interp;
+		double rX = train.lastRenderX + (train.renderX - train.lastRenderX) * interp;
+		double rY = train.lastRenderY + (train.renderY - train.lastRenderY) * interp;
+		double rZ = train.lastRenderZ + (train.renderZ - train.lastRenderZ) * interp;
+		x -= iX - rX;
+		y -= iY - rY;
+		z -= iZ - rZ;
+		
 		GL11.glTranslated(x, y, z);
 
 		float yaw = entity.rotationYaw;