Render Diagonal Items properly

- Fixed position offsets for diagonal belts for both rendering and item ejects
- Blocks render stacks similar to ground items with random horizontal offsets
- Items on diagonal belts now render at 45 degree angles
- Ejecting from a belt now has a minimum motion to prevent items from getting stuck

src/main/java/com/simibubi/create/modules/contraptions/relays/belt/BeltInventory.java

@@ -9,6 +9,7 @@ import java.util.Random;
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.foundation.utility.VecHelper;
 import com.simibubi.create.modules.contraptions.relays.belt.AllBeltAttachments.BeltAttachmentState;
+import com.simibubi.create.modules.contraptions.relays.belt.BeltBlock.Slope;
 
 import net.minecraft.block.Block;
 import net.minecraft.block.BlockState;
@@ -19,6 +20,7 @@ import net.minecraft.nbt.ListNBT;
 import net.minecraft.tileentity.TileEntity;
 import net.minecraft.util.Direction;
 import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.MathHelper;
 import net.minecraft.util.math.Vec3d;
 import net.minecraft.util.math.Vec3i;
 import net.minecraft.world.World;
@@ -362,8 +364,8 @@ public class BeltInventory {
 	public void eject(TransportedItemStack stack) {
 		ItemStack ejected = stack.stack;
 		Vec3d outPos = getVectorForOffset(stack.beltPosition);
-		Vec3d outMotion = new Vec3d(belt.getBeltChainDirection()).scale(Math.abs(belt.getBeltMovementSpeed())).add(0,
+		float movementSpeed = Math.max(Math.abs(belt.getBeltMovementSpeed()), 1 / 8f);
-				1 / 8f, 0);
+		Vec3d outMotion = new Vec3d(belt.getBeltChainDirection()).scale(movementSpeed).add(0, 1 / 8f, 0);
 		outPos.add(outMotion.normalize());
 		ItemEntity entity = new ItemEntity(belt.getWorld(), outPos.x, outPos.y + 6 / 16f, outPos.z, ejected);
 		entity.setMotion(outMotion);
@@ -372,8 +374,16 @@ public class BeltInventory {
 	}
 
 	private Vec3d getVectorForOffset(float offset) {
+		Slope slope = belt.getBlockState().get(BeltBlock.SLOPE);
+		int verticality = slope == Slope.DOWNWARD ? -1 : slope == Slope.UPWARD ? 1 : 0;
+		float verticalMovement = verticality;
+		if (offset < .5)
+			verticalMovement = 0;
+		verticalMovement = verticalMovement * (Math.min(offset, belt.beltLength - .5f) - .5f);
+
 		Vec3d vec = VecHelper.getCenterOf(belt.getPos());
-		vec = vec.add(new Vec3d(belt.getBeltFacing().getDirectionVec()).scale(offset - .5f));
+		vec = vec.add(new Vec3d(belt.getBeltFacing().getDirectionVec()).scale(offset - .5f)).add(0, verticalMovement,
+				0);
 		return vec;
 	}
 
@@ -388,7 +398,11 @@ public class BeltInventory {
 	private BlockPos getPositionForOffset(int offset) {
 		BlockPos pos = belt.getPos();
 		Vec3i vec = belt.getBeltFacing().getDirectionVec();
-		return pos.add(offset * vec.getX(), offset * vec.getY(), offset * vec.getZ());
+		Slope slope = belt.getBlockState().get(BeltBlock.SLOPE);
+		int verticality = slope == Slope.DOWNWARD ? -1 : slope == Slope.UPWARD ? 1 : 0;
+
+		return pos.add(offset * vec.getX(), MathHelper.clamp(offset, 0, belt.beltLength - 1) * verticality,
+				offset * vec.getZ());
 	}
 
 	private boolean movingPositive() {

src/main/java/com/simibubi/create/modules/contraptions/relays/belt/BeltShapes.java

@@ -42,7 +42,7 @@ public class BeltShapes {
 		if (slope == Slope.VERTICAL)
 			return VERTICAL_STRAIGHT.get(axis);
 
-		if (part != Part.MIDDLE) {
+		if (part != Part.MIDDLE && part != Part.PULLEY) {
 			boolean upward = slope == Slope.UPWARD;
 			if (part == Part.START)
 				upward = !upward;

src/main/java/com/simibubi/create/modules/contraptions/relays/belt/BeltTileEntityRenderer.java

@@ -1,5 +1,7 @@
 package com.simibubi.create.modules.contraptions.relays.belt;
 
+import java.util.Random;
+
 import com.mojang.blaze3d.platform.GlStateManager;
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.foundation.utility.IndependentShadowRenderer;
@@ -8,6 +10,7 @@ import com.simibubi.create.modules.contraptions.base.IRotate;
 import com.simibubi.create.modules.contraptions.base.KineticTileEntity;
 import com.simibubi.create.modules.contraptions.base.KineticTileEntityRenderer;
 import com.simibubi.create.modules.contraptions.base.KineticTileEntityRenderer.BlockModelSpinner;
+import com.simibubi.create.modules.contraptions.relays.belt.BeltBlock.Slope;
 import com.simibubi.create.modules.contraptions.relays.belt.BeltInventory.TransportedItemStack;
 
 import net.minecraft.block.BlockState;
@@ -44,13 +47,26 @@ public class BeltTileEntityRenderer extends TileEntityRenderer<BeltTileEntity> {
 			Vec3i directionVec = te.getBeltFacing().getDirectionVec();
 			Vec3d beltStartOffset = new Vec3d(directionVec).scale(-.5).add(.5, 13 / 16f + .125f, .5);
 			GlStateManager.translated(x + beltStartOffset.x, y + beltStartOffset.y, z + beltStartOffset.z);
+			Slope slope = te.getBlockState().get(BeltBlock.SLOPE);
+			int verticality = slope == Slope.DOWNWARD ? -1 : slope == Slope.UPWARD ? 1 : 0;
+			boolean slopeAlongX = te.getBeltFacing().getAxis() == Axis.X;
 
 			for (TransportedItemStack transported : te.getInventory().items) {
 				GlStateManager.pushMatrix();
 				float offset = MathHelper.lerp(partialTicks, transported.prevBeltPosition, transported.beltPosition);
-
 				float sideOffset = MathHelper.lerp(partialTicks, transported.prevSideOffset, transported.sideOffset);
-				Vec3d offsetVec = new Vec3d(directionVec).scale(offset);
+				float verticalMovement = verticality;
+
+				if (offset < .5)
+					verticalMovement = 0;
+				verticalMovement = verticalMovement * (Math.min(offset, te.beltLength - .5f) - .5f);
+				Vec3d offsetVec = new Vec3d(directionVec).scale(offset).add(0, verticalMovement, 0);
+				boolean onSlope = slope != Slope.HORIZONTAL
+						&& MathHelper.clamp(offset, .5f, te.beltLength - .5f) == offset;
+				float slopeAngle = onSlope
+						? slope == Slope.DOWNWARD ^ te.getDirectionAwareBeltMovementSpeed() > 0 ? -45 : 45
+						: 0;
+
 				GlStateManager.translated(offsetVec.x, offsetVec.y, offsetVec.z);
 
 				boolean alongX = te.getBeltFacing().rotateY().getAxis() == Axis.X;
@@ -70,6 +86,11 @@ public class BeltTileEntityRenderer extends TileEntityRenderer<BeltTileEntity> {
 				RenderHelper.enableStandardItemLighting();
 
 				int count = (int) (MathHelper.log2((int) (transported.stack.getCount()))) / 2;
+				GlStateManager.rotated(slopeAngle, slopeAlongX ? 0 : 1, 0, slopeAlongX ? 1 : 0);
+				if (onSlope)
+					GlStateManager.translated(0, 1 / 8f, 0);
+				Random r = new Random(transported.angle);
+
 				for (int i = 0; i <= count; i++) {
 					GlStateManager.pushMatrix();
 
@@ -79,11 +100,18 @@ public class BeltTileEntityRenderer extends TileEntityRenderer<BeltTileEntity> {
 						GlStateManager.rotated(90, 1, 0, 0);
 					}
 
+					if (blockItem) {
+						GlStateManager.translated(r.nextFloat() * .25f, 0, r.nextFloat() * .25f);
+					}
+
 					GlStateManager.scaled(.5, .5, .5);
 					itemRenderer.renderItem(transported.stack, TransformType.FIXED);
 					GlStateManager.popMatrix();
+
+					if (!blockItem)
 						GlStateManager.rotated(10, 0, 1, 0);
-					GlStateManager.translated(0, 1 / 16d, 0);
+					GlStateManager.translated(0, blockItem ? 1 / 64d : 1 / 16d, 0);
+
 				}
 
 				RenderHelper.disableStandardItemLighting();