What is Multisampling?
Multisampling is an antialiasing technique that evaluates geometric coverage at several positions within each pixel. It shares selected shading calculations across samples to reduce cost relative to full supersampling.
How Multisampling works
Multisample antialiasing stores several coverage samples for each rasterized pixel while usually running the fragment shader fewer times than full supersampling. At polygon boundaries, those samples record which parts of the pixel are covered, and a resolve operation combines them into one display value. Interior pixels often gain little because all samples see the same primitive. It belongs in the rendering stage and mainly improves geometric edges, not every source of shimmer or texture aliasing.
Key facts
- An MSAA framebuffer needs multisampled color data and usually multisampled depth and stencil data, increasing memory traffic before the final resolve.
- Alpha-tested foliage and shader-generated edges may receive little benefit because ordinary MSAA tracks polygon coverage rather than arbitrary transparency changes.
- Sample count is constrained by the graphics API, attachment formats, and hardware; requesting an unsupported count can make framebuffer creation fail.
When Multisampling matters
Enable multisampling when polygon edges need smoothing without shading every sample independently. Higher sample counts reduce jagged edges but consume more memory, bandwidth, and rendering time.