--- title: What Makes a Good Physics Engine? | Erin Catto | daily.dev description: A technical discussion on achieving floating-point determinism in physics engines. Key challenges include platform-specific math library differences (Windows... canonical: https://daily.dev/posts/what-makes-a-good-physics-engine-erin-catto-rpq8qqyrb twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: What Makes a Good Physics Engine? | Erin Catto | daily.dev og:description: A technical discussion on achieving floating-point determinism in physics engines. Key challenges include platform-specific math library differences (Windows... og:url: https://daily.dev/posts/what-makes-a-good-physics-engine-erin-catto-rpq8qqyrb og:image: https://api.daily.dev/og/posts/RpQ8QqyrB.png og:image:alt: What Makes a Good Physics Engine? | Erin Catto og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # What Makes a Good Physics Engine? | Erin Catto **[Game Engineering Podcast](https://daily.dev/sources/game_eng_podcast)** · 1 min read · 0 upvotes · 0 comments ## Summary A technical discussion on achieving floating-point determinism in physics engines. Key challenges include platform-specific math library differences (Windows MSVC vs Linux/Mac trig functions), FMA instruction variations between platforms, and SIMD instructions like fast reciprocal square root behaving differently across NEON, SSE2, and AVX. Solutions include disabling fast math/contractions compiler flags and implementing custom trig functions. Multi-threading order sensitivity is also highlighted as a critical determinism concern. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Bringing Correctly Rounded Math to Production with LLVM-libc](https://daily.dev/posts/bringing-correctly-rounded-math-to-production-with-llvm-libc-qxf42bmgd) · DevBlogs · 0 upvotes · 0 comments - [It's OK to compare floating-points for equality](https://daily.dev/posts/it-s-ok-to-compare-floating-points-for-equality-afhwereuq) · Lobsters · 3 upvotes · 0 comments - [Controlling Floating-Point Determinism in NVIDIA CCCL](https://daily.dev/posts/controlling-floating-point-determinism-in-nvidia-cccl-6nljr7dnj) · NVIDIA Developer · 0 upvotes · 0 comments - [Moving integer division to floating-point is trivial](https://daily.dev/posts/moving-integer-division-to-floating-point-is-trivial-7s6ttpx3b) · MBR · 1 upvotes · 2 comments --- [View this post on daily.dev](https://daily.dev/posts/what-makes-a-good-physics-engine-erin-catto-rpq8qqyrb) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"What Makes a Good Physics Engine? | Erin Catto","url":"https://daily.dev/posts/what-makes-a-good-physics-engine-erin-catto-rpq8qqyrb","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/what-makes-a-good-physics-engine-erin-catto-rpq8qqyrb"},"datePublished":"2026-07-26T16:09:36.345Z","dateModified":"2026-07-26T16:09:51.831Z","description":"A technical discussion on achieving floating-point determinism in physics engines. 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