Real-time rendering

Real-time rendering is the process by which a computer continuously computes and displays 3D images immediately so a user can see interactive results without noticeable delay. It requires rapid calculation of geometry, lighting, shading, and post-processing within a strict time budget (frame budget) to maintain smooth frame rates and low latency. In 3D contexts such as games, AR, VR and other XR applications, techniques like culling, level-of-detail, GPU shaders, and increasingly real-time ray tracing are used to balance visual fidelity with performance.

Imagine a VR experience where you walk through a virtual city: real-time rendering recalculates buildings, shadows, and reflections every frame as you move or change viewpoint. 3D artists must optimize assets (e.g., reduce polygon counts, use texture atlases and normal maps) so the engine can meet the frame budget. For AR on a smartphone there are extra constraints — overlay rendering, tracking corrections and power consumption — so techniques like foveated rendering and occlusion culling are used to reduce GPU work while keeping perceived quality high.