Nether Portal (block)

Obtaining

The nether portal block can not be obtained as an item even by using the /give command. The item form is completely nonexistent in Java Edition, but it can be obtained through add-ons or external editors in Bedrock Edition, or through using multiple glitches at once.

The nether portal block can be placed using commands such as /fill or /setblock and is generated when a nether portal is lighted.

Usage

Nether portal blocks can stably exist only within a nether portal structure, unlike end portal blocks. When the block is updated and detects it is not part of such a structure, it is destroyed.

Nether portal blocks can be used to teleport entities between the Nether and the Overworld. When a player in the Overworld or the Nether stands in a nether portal block for 4 seconds, the player is taken to the other dimension. While in the nether portal block, the player can neither open their inventory nor interact with blocks with GUI. The player can step out of a portal before it completes its animation to abort the teleport. However, in Creative mode there is no wait time—the player immediately transfers between dimensions. If there is already an active portal within range (125 blocks) in the other world, the player appears in that portal. Otherwise, a portal is created at or near the corresponding coordinates. If a single portal block is placed using commands, it can still be used to travel to the Nether.

Nether portal blocks make distinctive sounds, and emit the same purple particles produced by endermen, endermites, and ender chests. Portal blocks emit a light level of 11, dimmer than a torch.

Falling block entities can be teleported through a portal, but a piston cannot push a block through.

Much like water or lava, portal blocks cannot be broken by tools except in Creative. However, portal blocks can be destroyed by explosions (even weak ones) and can be replaced by placing water or lava sources in the same block (can also be done by dispensers). If any portal block is destroyed, the whole portal is deactivated as adjacent portal blocks are updated and detect that the portal structure is no longer complete.

While nether portals themselves cannot be lit in the End, a portal block set in the End and in custom dimensions behave exactly like in the Overworld, calculating coordinates in the Nether with the same 1:8 ratio. They teleport players to the Nether in Java Edition, and to the Overworld in Bedrock Edition.

Piston interactivity

Nether portal blocks cannot be pushed by pistons. They also cannot be pushed or pulled by sticky pistons.

Sounds

Generic

Java Edition:

Bedrock Edition:

Unique

Java Edition:

Bedrock Edition:

Data values

ID

Java Edition:

Bedrock Edition:

Block states

Java Edition:

Bedrock Edition:

History

History of the block itself

This section would benefit from the addition of more images. 

Please remove this notice once you've added suitable images to the article.
The specific instructions are: The block may have been way lighter at some point in Pocket Edition's history: https://youtu.be/5N0x7X-nkCQ&t=3m27s

Java Edition Alpha
v1.2.0		preview			File:Nether Portal (NS) JE1.png Added the nether portal block.
					It currently cannot be destroyed by flowing fluids.
Java Edition Beta
1.6		Test Build 3			Nether portal blocks no longer have a top face.
Java Edition
1.0.0		Beta 1.9 Prerelease 6			Nether portal blocks are no longer affected by smooth lighting.[1]
		RC1			It is no longer possible to break portal blocks with water or lava. Both stop before hitting the portal and act as if the portal were a solid block; placing water instead of fire in the portal automatically deactivates the portal anyway.
1.2.1		12w08a			The player can now (again) break a block portal in creative by punching it. It makes the same sound as glass being destroyed.
1.5		13w02a			Nether portal blocks now use the texture in resource packs: textures/blocks/portal.png.
1.7.2		13w37a			Nether portal blocks now use block data values (later changed to block state) to determine their orientation. Due to these changes, nether portals created in 1.6.4 and earlier have a tendency to close when upgrading.
					Metadata value 1 corresponds to a portal that reaches the west and east sides of the block, and 2 corresponds to one that touches the north and south sides. 0, 3, 4, 6, 7, 8, 10, 11, 12, 14 and 15 also appear as north/south and 5, 9 and 13 as east/west, however they appear to be unused.
		13w37b			Nether portal blocks with damage value 3, 7, 11 and 15 now have a vertical post appearance rather than the pane or sheet appearance of other states.
		13w41a			Nether portals, water and ice are now visible through each other.
					This also makes the rear planes visible from the front planes.
		13w42a			Nether portals no longer show their back face.
1.8		14w03a			Nether portal blocks with data values 3, 7, 11 and 15 now appear as north-south connected again.
		14w18a			Nether portals no longer have side faces.
1.13		17w47a			Prior to The Flattening, this block's numeral ID was 90.
		pre5			The block ID of nether portals has been changed to nether_portal.
Pocket Edition Alpha
v0.12.1		build 1			[verify] Added nether portal blocks.
Legacy Console Edition
TU1	CU1	1.0	Patch 1	1.0.1	[verify] Added nether portal blocks.

History of the block's effects

Nether portal "item"

The following content is transcluded from Technical blocks/Nether Portal.

Appearances

Java Edition Alpha
v1.2.0		preview			Nether portal items have an unstable item model which changes depending on blocks which are targeted or in loaded chunks. It uses this model in inventories, when held in first or third person view or as a dropped item.
					Initially the Nether portal item would appear as a full cube like many other blocks, but targeting an existing portal block would cause the item to morph into its shape:
					Having an existing nether portal block within loaded chunks also appears to influence the shape of the nether portal item. For example, if no existing blocks are loaded, the item may appear in its full cube state, but loading a chunk containing an north-south oriented nether portal will result in the item automatically becoming north-south.
Java Edition Beta
1.6		Test Build 3			Block items have changed in this version to be brighter and rotated 90 degrees clockwise from their prior appearances. The "pane" appearance shapes can be seen to have been inverted as a result, with east-west oriented how north-south was previously and vice versa.
1.8		Pre-release			Block items are now far brighter than before.
Java Edition
1.0.0		RC2			Block items are now more shaded again.
1.3.1		12w22a			Block items have been rotated back to their pre-Beta 1.6 orientations.
1.4.2		12w34a			Block items have been brightened to an almost unnoticeable degree.
1.7.2		13w37b			With the addition of post-shaped nether portals, the item can take on this shape as well.
		13w42a			Nether portal items now appear translucent in the inventory. As a dropped item, in a player's hand, or in an item frame, they still appear opaque.
		13w42b			Nether portal items now appear translucent when dropped or in an item frame.
1.7.4		13w47a			Nether portal items now appear translucent when held, in both first person and third person.
1.8		14w18a			The Nether portal item form is now 2D.
Bedrock Edition
?					The nether portal item looks like this, and does not shapeshift in response to existing blocks. However, if it is updated, it will break.

Names

Java Edition

Item (and block) names did not exist prior to Beta 1.0.

• Beta 1.0 - 14w25a: Portal
• (As block name, item does not exist) 14w25a - 17w47a: Portal
• (As block name, item does not exist) 17w47a and onwards: Nether Portal

Bedrock Edition

• ? - ?  : Portal

Texture generation prior to Java Edition 13w02a and Bedrock Edition v0.15.0

Due to the large number of Atan2 and Sine operations, all frames of animation (a total of 32, at a resolution of 16×16) for the portal block are generated once at-startup and stored into an internal animation strip; The random shimmer is the same every time, as the game always uses a random number generator with a seed of 100L.

To generate one frame of the nether portal animation:

# assume time is a value from 0 to 1; a value of 1 will result in
# the same image as a time value of 0 (excluding the random shimmering effect)
def setup_portal_sprite (time: float, output: Image):
	random = Random(100)
	wide, tall = output.size
	for x in range(wide):
		for y in range(tall):
			n = 0.0
			for dir in range(2):
				# All in this loop is done twice to create two spirals,
				# one of which offset to the topright
				spiral_x = (x - dir * (wide // 2)) / wide * 2.0
				spiral_y = (y - dir * (tall // 2)) / tall * 2.0
				
				spiral_x += 2 if spiral_x < -1 else -2 if spiral_x >= 1 else 0
				spiral_y += 2 if spiral_y < -1 else -2 if spiral_y >= 1 else 0

				mag = spiral_x ** 2.0 + spiral_y ** 2.0
				out_spiral = atan2(spiral_y, spiral_x)

				# Mag is used here to make the arms of the spiral constrict
				# the further from the centre of the spiral they are
				out_spiral += ((time * pi * 2) - (mag * 10) + (dir * 2)) * (dir * 2 - 1)
				
				# `(i * 2 - 1)` will reverse the direction of the spiral if is 0
				# `* 0.5 + 0.5` will bring the spiral into the range of 0 to 1 rather than -1 to 1
				out_spiral = sin(out_spiral) * 0.5 + 0.5
				
				# make the intensity of the spiral's arms diminish with distance from the centre
				out_spiral /= mag + 1
				
				# divide by two so that the final range is 0 to 1 instead of 0 to 2,
				# as we're generating two spirals
				n += out_spiral / 2

			n += random.range(0.0, 0.1) # make the spirals shimmer slightly at random
			
			r = int(n ** 2 * 200 + 55)
			g = int(n ** 4 * 255)
			b = int(n * 100 + 155)
			output.set_pixel(x, y, r, g, b, b) # blue is used for transparency

The portal block is the only one of the procedural textures that is ported 1:1 in the 1.5 resource pack changes; Unlike the water animations, the alpha channel was not made uniform in the 1.15 texture update.

Issues

Issues relating to "Nether Portal (block)" are maintained on the bug tracker. Report issues there.

References