Firework Rocket

Firework rockets are items which, when activated, create colorful explosions. The color, fade, shape and effect of the explosion are determined by what ingredients are used to create the firework star - one of the ingredients used to create a rocket. However, a firework rocket can be crafted without a firework star. When this happens, it will only have a rocket trail, with no colorful explosion. The height of a rocket can be altered by adding up to 3 gunpowder to the rocket recipe. This increases the flight duration by 1 per gunpowder. Multiple firework stars can also be used, in which case each one will go off simultaneously when the rocket detonates. Firework rockets can be activated by right-clicking any block with them, or they can be fired out of dispensers. The fireworks are customizable in colors, shapes, and height. Their flight path is random and sometimes are offset up to 5 blocks to the side, they also tend to spiral up. Fireworks are also affected by gravity. Their motion can be changed with TNT or flowing water.

There is a delay between detonation and the player hearing the sound, emulating real fireworks, but this sound travels much more slowly than in the real world. Jeb mentioned on Twitter that fireworks may have effects on mobs, such as scaring wolves.

If a rocket's path is hindered by any solid block it will do one of three things: stay under the block as if caught there until it explodes (more likely to happen if the firework has a shorter flight duration), explode upon contact (if this happens the explosion will appear above the block, even though the rocket did not go above it, unless there are more than one block), or stay under the block for a few seconds then fly off more to the side (more likely to happen with longer duration). If a rocket with any kind of explosion ingredient detonates under a block, the explosion pattern will appear flattened against the ground in a wide, disc-like fashion.

Crafting
The Firework Rocket is one of two items in the game (the other being the Command Block) that cannot be taken directly out of a creative inventory. When the rocket is launched in lava, the rocket will catch fire, but will reach its intended height and explode as normal. When launched in fire, the rocket will briefly catch and extinguish quickly, reach its intended height, and explode as normal. Neither lava nor fire changes the motion of the rocket. Fireworks can explode over the 256 block height limit. Firework rockets can also travel through nether portals if fired inside a nether portal; they will stay at the top of the portal, unable to go higher, then they will go through the portal. A rocket will not be visible under a cloud when it explodes.

Duration
When the item is hovered over in the inventory it displays the flight duration (e.g. "Flight Duration: 1").

Rough distance (in blocks) that the rocket travels depending on the flight duration.
 * 1 gunpowder: 12-21 blocks
 * 2 gunpowder: 23-38 blocks
 * 3 gunpowder: 40-57 blocks with a few exploding at 35 and 36 blocks.

Results obtained by 576 fireworks per type being set off. Using small balled and red firework stars.

Shape effects
A firework can only have one shape effect for each firework star used in the recipe. A combination of firework stars can be used on the same firework rocket when crafting.

Additional effects
In addition to the shape effects, you may add either or both of these additional effects.(Place one or both of them anywhere during the making of the Firework Star.)

Bugs

 * If a rocket explodes very close to water and/or ice, all of the nearby water and/or ice may appear invisible for a fraction of a second.
 * If a rocket explodes near a Nether portal, the portal blocks may turn invisible for a fraction of a second.
 * The small ball firework star very rarely does not work.
 * Launching rockets in flowing water may cause Minecraft to slow down and freeze, even after the rockets have all finished exploding.
 * If a rocket is placed on the side of a wall of blocks, the rocket often becomes stuck in or on the side of the block.
 * A burning rocket entity can remain underwater without the fire being extinguished.
 * In SMP, if you launch a firework with no firework star, a Java exception kills your connection and will occur every time you try to log back in.
 * When launching empty fireworks, this will prompt 'End of Stream' on multiplayer unless it has been named on an anvil. It will have no effect on singleplayer.
 * Rocket explosions can be heard on the title screen if launched quickly before you save and quit.
 * When placed in a Nether portal, rockets quickly teleport to the Nether, where they will not explode until you enter the Nether. If you send enough rockets with firework stars through the portal, a massive colorful explosion will wait for you on the other side. This does not work in the reverse way; the rockets explode soon after reaching the Overworld.

Trivia

 * Rockets that explode underwater look the exact same as those that explode above water.
 * Flowing water can be used very effectively to angle rockets.
 * Even though rockets have an explosion, it does not affect items, mobs, or destroy blocks.
 * Rockets cannot cause TNT or Ender crystals to explode.
 * Even if knocked into a horizontal trajectory by water or an explosion, rockets always point straight upward.
 * Rockets can be launched from a Dispenser, however will only launch upwards from the block directly in front of the dispenser.
 * The crackling sound of a firework is the same as the sounds you hear as the Ender Dragon is killed.
 * Shooting a rocket into a cobweb causes it to slow down as expected, the explosion particles are slowed down too, creating a colorful ball inside the web.
 * Rockets launched in lava will catch fire as they go up.