How to make objects slide over walls in bump.lua?

Use the 'slide' collision response in your filter function when moving an item. For example, return 'slide' for wall collisions in the filter, and bump.lua will automatically adjust the movement to slide along surfaces.

bump.lua or HardonCollider for my Lua game?

Choose bump.lua for fast, memory-efficient AABB collisions and simple gameistic responses. Opt for HardonCollider if you need polygonal shapes or more complex physics simulations, as the README suggests for non-AABB needs.

Can I use bump.lua for circle collisions?

No, bump.lua only supports axis-aligned rectangles. You would need to approximate circles with squares or use a different library like HardonCollider, which handles various shapes.

How to set up spatial queries with bump.lua in LÖVE?

Add all relevant items to the world with world:add, then use methods like queryRect to retrieve items in a specific area. For instance, call world:queryRect(cameraX, cameraY, width, height) to get visible objects for rendering.

What's the best cell size for bump.lua in a tile-based game?

Set the cell size to a multiple of your tile size, such as 32, 64, or 128. The README recommends experimenting, as it balances performance and collision accuracy, with larger cells for sparser games.

How to create a custom collision response in bump.lua?

Register a new response using world:addResponse with a name and a function. Study the source code of built-in responses like slide or bounce to understand the required parameters and return values.

Open-Awesome

Bump

MITLuademo-2.0.0

A fast, game-oriented collision detection library for Lua focused on axis-aligned rectangles.

GitHub

1.1k stars85 forks0 contributors

What is Bump?

bump.lua is a collision detection library for Lua that specializes in axis-aligned bounding box (AABB) collisions. It is designed for 2D games where performance and simplicity are key, offering fast detection and basic collision responses like sliding and bouncing. The library prevents tunneling and supports spatial queries, making it a versatile tool for game developers.

Target Audience

Lua game developers, particularly those using frameworks like LÖVE, Corona SDK, or Cocos2d-x, who need efficient collision detection for tile-based games, platformers, or top-down adventures.

Value Proposition

Developers choose bump.lua for its speed, minimal memory footprint, and game-focused design. Unlike heavier physics engines, it provides just enough collision handling for most 2D game genres without unnecessary complexity.

Overview

A collision detection library for Lua

Use Cases

Best For

Tile-based games where entities are mostly rectangular
Platformers like Super Mario that require sliding collision responses
Top-down adventure games such as Zelda
Shoot 'em ups and fighting games with fast-moving projectiles
Games needing lightweight spatial queries for rendering or interaction
Scenarios where realistic physics simulations are unnecessary

Not Ideal For

Games requiring polygonal or circular collision shapes for accurate hitboxes
Simulations needing realistic physics like object stacking, rolling, or continuous interactions
Projects where collision resolution order must be deterministic and objects move simultaneously

Pros & Cons

Pros

Fast AABB Detection

Optimized solely for axis-aligned bounding boxes, enabling high performance and simple integration, as highlighted in the README's focus on speed over realism.

Built-in Tunneling Prevention

Treats all items as 'bullets' to prevent fast-moving objects from passing through others, a critical feature for fast-paced games like shoot 'em ups.

Gameistic Collision Responses

Provides basic response types like slide, bounce, touch, and cross, tailored for gameplay mechanics such as platformer movement, with filter functions for customization.

Versatile Spatial Queries

Can query items by point, rectangle, or segment, doubling as a lightweight spatial database for rendering optimizations or interaction detection.

Cons

Limited to Rectangles Only

Does not support polygons, circles, or other shapes, requiring workarounds or switching to libraries like HardonCollider for complex geometries, as admitted in the README.

Sequential Collision Resolution

Moves and collides objects one at a time, which can lead to order-dependent behavior and is unsuitable for simulations requiring simultaneous interactions.

Manual Item Management

Requires explicit calls to add, remove, and update items, adding boilerplate code compared to more automated physics engines.

Frequently Asked Questions

Related Projects

awesome-love2d

A curated list of amazingly awesome LÖVE libraries, resources and shiny things.

Stars4,327

Forks240

Last commit22 days ago

inspect.lua

Human-readable representation of Lua tables

Stars1,525

Forks200

Last commit3 months ago

lume

Lua functions geared towards gamedev

Stars1,216

Forks88

Last commit2 years ago