multisampled

Multisampled refers to a technique in computer graphics where multiple samples per pixel are taken during rasterization to reduce aliasing. It is most commonly implemented as multisample anti-aliasing (MSAA). Unlike supersampling, which samples the entire pixel area, MSAA tests several sub-pixel locations for geometry coverage and typically shades only once per pixel, then blends the results from the covered samples. This yields smoother edges with less performance cost than full supersampling.

How it works: During rasterization, multiple sub-pixel sample points within each pixel are evaluated for coverage by the scene’s geometry. The edge samples contribute to an edge-coverage mask, while interior samples may be fully covered. Shading is usually performed per pixel, and the final color is formed by blending the per-sample colors according to their coverage. If the rendering uses a multisampled render target, a resolve step converts the multisampled image into a single-sample image for display. Multisampled textures and render targets enable this process within the graphics pipeline.

Configurations and hardware support: common multisample counts are 2x, 4x, and 8x samples per pixel. More samples improve edge quality but increase memory usage and bandwidth. Modern graphics APIs expose MSAA as a feature of the render target and may offer options like sample shading or per-sample lighting. Compatibility and driver support are typically robust on contemporary GPUs.

Limitations and alternatives: MSAA mainly mitigates polygon edge aliasing and is less effective for texture aliasing or shimmering within flat areas. For those issues, alternatives such as supersampling anti-aliasing (SSAA) or post-processing approaches like FXAA and TXAA are used, trading off performance and quality differently.