[#396] Entities: Physics

[](https://www.bountysource.com/issues/46548044-396-entities-physics)

This issue is part of [this story](https://github.com/GlowstoneMC/Glowstone/issues/396), *Completing entities in Glowstone* (#396). To make the work easier and bounties fairer, we've split it into multiple issues.

Anyone can participate in the completion of this issue, which will be a major turning point in the development and the possible use-cases for Glowstone as a Minecraft server alternative.

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**Before getting started!** If you are unfamiliar with Glowstone, please remember that Glowstone is a complete rewrite of the Minecraft vanilla server, aimed to be a better alternative to other software like Spigot. You are by no means allowed to push code to this repository based on Mojang's own platform (whether it be Forge, MCP, decompiled binaries, etc.) Doing so will cause in the rejection of your Pull Request. You are allowed to use other resources like the numerous wikis that exist on the Internet (Minecraft Wiki, wiki.vg, etc.) as well as trial-and-error.

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Physics
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Although we have worked on improving physics recently, there is still much work to do in order to achieve the same results as the Vanilla software. This includes:

* Fixing physics for Dropped Items (inconsistent, may throw very far away depending on player orientation)
* ~Knockback (inconsistent with the Vanilla server; not smooth, entities are knocked-back to extreme distances)~
* Velocity in general (not consistent with the Vanilla server)
* Water drag

No files or tests are named, so begin by reproducing dropped-item physics, general velocity, and water drag in Glowstone and compare the results with vanilla using permitted wiki resources and trial-and-error. Done means these behaviors are consistent with vanilla, including the listed dropped-item, knockback, velocity, and water-drag cases.

Written by the indexing model from the issue text.