ForwardRendering

Forward rendering is a real-time shading technique in which lighting calculations are performed during the per-fragment shading pass as geometry is rasterized, rather than in a separate geometry-to-image pass. In a typical forward pipeline, for each visible fragment the shader evaluates material properties and lighting, accumulating contributions from lights such as directional, point, and spot lights. Shadows can be added via shadow maps or other shadowing methods, and transparency often requires additional blending passes.

Compared with deferred rendering, forward rendering computes lighting directly during fragment shading, avoiding a separate G-buffer pass. This makes forward rendering simpler to implement on some hardware, and it handles transparent objects and multisample anti-aliasing (MSAA) more naturally. However, its performance typically scales with the number of lights affecting the scene, since each fragment may shade against many lights. This can limit efficiency in scenes with large numbers of dynamic lights or complex per-pixel materials, and global illumination effects are harder to achieve purely within a forward scheme.

Variants and optimizations exist to improve scaling. Forward+ rendering uses screen-space tiling to cull lights per tile, enabling per-fragment shading to consider only lights relevant to nearby screen regions, which helps when there are many lights. Hybrid approaches may combine forward rendering for transparent and foreground elements with other techniques for opaque geometry.

Applications of forward rendering include many real-time graphics engines, especially in games and mobile platforms where simplicity, broad hardware compatibility, and strong support for transparency and MSAA are valuable. It remains a foundational method alongside deferred rendering, with choices guided by scene characteristics and target hardware.