The depiction of the sky has become one of the most computationally expensive and artistically important systems in modern open-world games, and Rockstar Games' upcoming Grand Theft Auto VI is widely expected to push this domain forward. Building on the volumetric cloud breakthroughs pioneered for Horizon Zero Dawn (Schneider and Vos, 2015) and the heavily customised sky system that shipped in Red Dead Redemption 2 (Rockstar Games, 2018), GTA VI is likely to combine ray-marched volumetric cloudscapes, physically based atmospheric scattering, and temporal upsampling to deliver a dynamic Florida-inspired sky that supports both diurnal weather cycles and emergent storm systems. This report surveys the relevant rendering theory, examines what is publicly known about Rockstar's RAGE-engine sky pipeline in RDR2, and extrapolates the techniques most plausibly being deployed in GTA VI.
Traditional real-time skies relied on a static cube-mapped skybox or a thin layer of two-dimensional billboarded cloud sprites scrolled across a dome. These approaches break down at low altitudes, when the camera flies through clouds, and at sunset when light must scatter through cloud interiors. Volumetric rendering replaces this with a true three-dimensional participating-medium integration: rays are marched from the camera through a virtual cloud "slab", sampling a density field at regular intervals and accumulating in-scattered light according to the radiative transfer equation (Wikipedia, 2025). The density field itself is typically reconstructed not from voxels but from a procedural composition of Perlin–Worley three-dimensional noise textures, which produce the convincing fractal billows and wispy edges of real clouds while remaining cheap to evaluate (Schneider and Vos, 2015).
The seminal real-time implementation is Andrew Schneider's Nubis system, presented at SIGGRAPH 2015 for Horizon Zero Dawn. Schneider's approach layers a low-frequency Perlin–Worley base shape, a high-frequency Worley detail texture, a two-dimensional weather map that controls coverage, cloud type and precipitation, and a height-signal function that biases stratus, stratocumulus or cumulus profiles depending on altitude (Guerrilla Games, 2015; Schneider and Vos, 2015). Lighting uses a stochastic six-sample cone-traced approximation of the Beer–Lambert law combined with Henyey–Greenstein anisotropic phase functions to recreate the characteristic "silver lining" and dark-bottomed cumulus look. To hit a 2 ms GPU budget on the PlayStation 4, Nubis renders only one in every sixteen pixels per frame and reprojects the missing samples temporally — a technique now standard across the industry (Schneider and Vos, 2015).
Red Dead Redemption 2 shipped on PlayStation 4 and Xbox One in 2018 with a sky system that critics repeatedly singled out as a generational leap (Rockstar Games, 2018). Although Rockstar has not published a SIGGRAPH paper detailing the implementation, several characteristics can be inferred from the shipped game and from teardown analysis by graphics enthusiasts. Clouds in RDR2 are unambiguously volumetric at low altitudes: the player can fly the in-game camera into a cumulus formation, see internal density variations, and observe how godrays form as direct sunlight is occluded by individual cloud lobes. The system also exhibits altitude layering — high cirrus sheets render above lower cumulus banks, and the boundary moves correctly as the camera ascends a mountain.
Critically, RDR2's clouds are tightly integrated with the engine's weather simulation. Storm fronts visibly build over many in-game minutes, with coverage rising, base altitude dropping and cloud type shifting from cumulus humilis to cumulonimbus before rain begins; this is precisely the behaviour one would expect from a coverage/cloud-type weather-texture parameterisation in the Nubis tradition (Schneider and Vos, 2015). Rockstar also augments the volumetric layer with a separate atmospheric scattering model that produces the warm horizon glow at golden hour and the characteristic blue-purple gradient at twilight, suggesting an analytical Rayleigh/Mie sky shader running underneath the volumetric pass. The fact that the system held up at 30 frames per second on base 2013 console hardware speaks to aggressive temporal reprojection and quarter-resolution rendering similar to that documented by Guerrilla.
Several public signals constrain what GTA VI is likely to deploy. The first trailer, released in December 2023, shows a Vice-City-inspired Floridian setting with towering tropical cumulus, dramatic sunset cloudscapes, and reflective wet streets after rain — all visual features that demand a fully volumetric, weather-coupled sky (Take-Two Interactive, 2023). Second, the game targets PlayStation 5 and Xbox Series X|S, platforms whose roughly 10 TFLOP GPUs and hardware-accelerated mesh shaders open up rendering budgets that were simply unavailable for RDR2.
Three specific advancements are highly plausible. First, higher-resolution volumetric marching: where RDR2 almost certainly rendered clouds at quarter-resolution with a 4×4 temporal reprojection grid, GTA VI can afford half-resolution marching with shorter step counts compensated by machine-learning denoisers or AMD FSR/Sony PSSR upsampling. Second, multiple-scattering approximations: techniques such as Hillaire's (2020) analytic multiple-scattering term, used in Frostbite and now widely adopted, would allow Rockstar to render the soft luminous interiors of Floridian thunderheads without paying for full path-traced light transport. Third, dynamic, gameplay-coupled weather: because the GTA VI map appears to include a hurricane-prone coastline, the cloud system likely exposes its weather-texture parameters to the gameplay scripting layer, allowing storms to be authored or seeded by mission events while still evolving physically between scripted beats. Finally, given Rockstar's well-documented attention to vehicular and water reflections, the volumetric cloud layer will almost certainly be sampled into screen-space reflection and planar-reflection passes so that puddles, car paint and ocean surfaces correctly mirror the live sky rather than a baked cubemap — a continuity of detail that RDR2 already partly achieved and that current-generation hardware makes routine.
Cloud rendering has moved in a decade from a decorative afterthought to one of the defining technical disciplines of open-world game development. The combination of procedural Perlin–Worley density fields, ray-marched radiative transfer, Henyey–Greenstein phase functions and temporal upsampling — codified by Guerrilla Games for Horizon Zero Dawn and visibly extended by Rockstar for Red Dead Redemption 2 — now constitutes an industry-standard recipe. For Grand Theft Auto VI, the most plausible direction is not a paradigm shift but a careful scaling of this recipe onto ninth-generation hardware: higher-resolution marching, multiple-scattering lighting, deeper coupling to gameplay-driven weather, and integration of the volumetric sky into the wider reflection and global-illumination pipeline. The result, if the 2023 trailer is representative, will be a Floridian sky that behaves as a first-class simulated system rather than a backdrop.
Guerrilla Games (2015) The Real-Time Volumetric Cloudscapes of Horizon Zero Dawn. Available at: https://www.guerrilla-games.com/read/the-real-time-volumetric-cloudscapes-of-horizon-zero-dawn (Accessed: 14 May 2026).
Hillaire, S. (2020) 'A Scalable and Production Ready Sky and Atmosphere Rendering Technique', Computer Graphics Forum, 39(4), pp. 13–22.
Rockstar Games (2018) Red Dead Redemption 2. New York: Rockstar Games.
Schneider, A. and Vos, N. (2015) 'The Real-Time Volumetric Cloudscapes of Horizon: Zero Dawn', in Advances in Real-Time Rendering in Games, SIGGRAPH 2015 Course Notes. New York: ACM. Available at: https://advances.realtimerendering.com/s2015/ (Accessed: 14 May 2026).
Take-Two Interactive (2023) Grand Theft Auto VI Trailer 1. Available at: https://www.rockstargames.com/VI (Accessed: 14 May 2026).
Wikipedia (2025) Volume rendering. Available at: https://en.wikipedia.org/wiki/Volume_rendering (Accessed: 14 May 2026).