Bullet
LiquidFun
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Bullet | LiquidFun | |
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41 | 12 | |
11,886 | 4,648 | |
2.0% | 0.6% | |
3.4 | 0.0 | |
14 days ago | about 1 year ago | |
C++ | C++ | |
GNU General Public License v3.0 or later | - |
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Bullet
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Blaze: A High Performance C++ Math library
For typical game physics engines... not that much. Math libraries like Eigen or Blaze use lots of template metaprogramming techniques under the hood that can help when you're doing large batched matrix multiplications (since it can remove temporary allocations at compile-time and can also fuse operations efficiently, as well as applying various SIMD optimizations), but it doesn't really help when you need lots of small operations (with mat3 / mat4 / vec3 / quat / etc.). Typical game physics engines tend to use iterative algorithms for their solvers (Gauss-Seidel, PBD, etc...) instead of batched "matrix"-oriented ones, so you'll get less benefits out of Eigen / Blaze compared to what you typically see in deep learning / scientific computing workloads.
The codebases I've seen in many game physics engines seem to all roll their own math libraries for these stuff, or even just use SIMD (SSE / AVX) intrinsics directly. Examples: PhysX (https://github.com/NVIDIA-Omniverse/PhysX), Box2D (https://github.com/erincatto/box2d), Bullet (https://github.com/bulletphysics/bullet3)...
- Looking for specific pre-Microsoft Havok Physics SDK version (2013, 2014)
- Software for Mechanism Analysis
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Does anyone know any good open source project to optimize?
I suspect most C++ physics libraries like Box2D (https://github.com/erincatto/box2d) or Bullet3 (https://github.com/bulletphysics/bullet3) could really benefit a lot from SIMD.
- After months of work, I'm excited to share the first release of Godot Jolt, an extension that integrates the Jolt physics engine into Godot, demonstrated using GDQuest's RoboBlast
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X4's Upcoming Multiplayer Features Are a Huge Step Forward
No, they replaced Bullet with Jolt. That is considerably more than "some adjustment", regardless of what you think of the result.
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Brick Breaker
Vulkan graphics via Intel GVK, and physics via Bullet
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Ive been programming for four years and I told my dad to watch long videos and complete your own projects to learn most efficiently. He thinks he’s ready to tackle any project after a ten minute video…
The first two have a bunch of great examples, and I’m tying them together by refactoring some of the THREE examples to fit the ECS paradigm defined in AFrame. then upping the ante by adding physics using AMMO, which is more challenging since it’s only a partial implementation of Bullet, and already poorly documented (yet popular) physics engine.
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Their music is just too good
Plus, SM uses a system called bullet physics, I imagine this would be rather complex to rework into a modern engine such as Unreal or Unity (after all, the majority of performance issues come from the physics engine rather than the graphics engine)
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Is anyone working on more effecient HDT-SMP?
The physics in HDT-SMP are actually being calculated outside of Skyrim's engine with Bullet, an open-source physics engine. So this isn't some limitation of Skyrim's engine.
LiquidFun
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My open-source Algodoo remake is releasing in alpha at the end of the month!
You can make thicker liquids like honey, and change their colors. You can mix liquids together as well. I'm using Google's LiquidFun to achieve this.
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How would I go about making a platform that wraps from one side of the screen to the other
Sadly the marketing department failed utterly, somehow thinking they could sell CFD to... the same kind of kids that spend 200 bucks on loot boxes. I think the absolutely batshit insane potential for dynamic 2D gameplay was barely scratched before they sold the code to Google (creating the LiquidFun project) and went their separate ways. These days the engine has branched into a lot of things, notably a 3D industrial version called ParticleWorks which is a CAD plugin for bringing SPH to mechanical engineering.
- Could I build an effect like this in threejs? If not could you point me in the right direction?
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Bachelor's Project - Need to make a VR game in ~400 hours total. Is my idea feasible?
This might help: https://google.github.io/liquidfun/
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Pixar's notes on Rigid Body Simulation (2001) [pdf]
Some years ago I did a project with LiquidFun; https://google.github.io/liquidfun/
It was an interactive art thing for kids; had a TV with a maze of transparent PVC pipes mounted on the front with valves (rotary encoders inside). The kids would open and close the valves, and watch the flow of water be redirected on the TV behind.
- Most Popular C[++] Open-Source Physics Engines
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Show HN: WASM and WebGL Fluid Simulation
yeah, I've played around with a few approaches for running the timestep and for some reason I don't feel like I get the same results as liquidfun.js.
their loop [0] is pretty simple; it's scheduled by `requestAnimationFrame`, advances time by 1/60th of a second, and runs their default of 3 particle iterations. it completes the physics simulation within 3.9–5.5ms, which is easily in time for the 16ms deadline. the rendering is WebGL, which I assume fits easily into that 16ms budget too.
my loop [1] is more complicated; I don't hardcode the timestep to 1/60 seconds, because requestAnimationFrame may be scheduled less frequently than that. so instead I advance time by the time elasped since I was last scheduled. hm, I think there's a mistake there — `lastMs = nowMs` is probably on the wrong side of the physics calculation.
there's an additional technique I use: I put a `Math.min()` over the simulation interval, so that I don't attempt to simulate more than 20ms (this can happen if you get scheduled infrequently due to hot CPU or backgrounding the app) — simulating too much time will make us fail our frame deadline anyway.
furthermore, if we are calculating more than 1/60th of a second, I employ more particle iterations (i.e. 3 particle iterations for every 1/60th of a second that passes). this gave me good results, but turns out it is based on incorrect assumptions (iterations are unrelated to timestep)[3]. moreover, I may be making mistakes in my decision of whether to round this fraction up/down.
if too few particle iterations for a timestep: the particles will bounce. if too many: the particles will look too incompressible[4]. I think that's the "solid-like" structure you're describing.
the main reason I complicated this is because the last one I did[5] made me feel motion-sick. I think if "every 1/60th, or 1/30th, or 1/20th of a second: you simulate a 1/60th of a second of time": the result (if you're not scheduled consistently) is that the world speed keeps changing. I think liquidfun.js's approach should be vulnerable to this, but for some reason it looks fine to me. maybe they get scheduled more consistently than me (even though by my measurements, my physics runs slightly faster, so should be able to achieve similar results).
I think I need to remind myself of what happens if I program the timestep in the simple way that liquidfun.js did. will try that out at some point.
[0] https://github.com/google/liquidfun/blob/master/liquidfun/Bo...
[1] https://github.com/Birch-san/liquidfun-play-2/blob/master/sr...
[2] https://github.com/Birch-san/liquidfun-play-2/blob/master/sr...
[3] http://google.github.io/liquidfun/Programmers-Guide/html/md_...
[4] http://google.github.io/liquidfun/Programmers-Guide/html/md_...
[5] https://birchlabs.co.uk/box2d-wasm-liquidfun/
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[AskJS] How could I implement realistic fluids simulations (SPH?) in my video game?
It should be possible to produce simulations like the ones they produced in JS: http://google.github.io/liquidfun/
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Hello!
He was involved in an open-source project titled LiquidFun, which was released late in 2013 and unfortunately only went through 3 versions, ending developmentin mid 2014. https://github.com/google/liquidfun/releases
What are some alternatives?
PhysX - NVIDIA PhysX SDK
Box2D - Box2D is a 2D physics engine for games
libGDX - Desktop/Android/HTML5/iOS Java game development framework
CHRONO - High-performance C++ library for multiphysics and multibody dynamics simulations
Chipmunk - A fast and lightweight 2D game physics library.
Newton Dynamics - Newton Dynamics is an integrated solution for real time simulation of physics environments.
Cocos2d - Cocos2d-x is a suite of open-source, cross-platform, game-development tools utilized by millions of developers across the globe. Its core has evolved to serve as the foundation for Cocos Creator 1.x & 2.x.
ODE
AndEngine - Free Android 2D OpenGL Game Engine
mujoco - Multi-Joint dynamics with Contact. A general purpose physics simulator.
jbox2d - a 2d Java physics engine, native java port of the C++ physics engines Box2D and LiquidFun