fragmentshaderperpixel

Fragment shader per-pixel, often referred to in documents as fragmentshaderperpixel, is the practice of computing shading for each fragment (the candidate pixel) using a fragment shader. In a rasterization-based pipeline, fragment shaders run for every fragment produced by the rasterizer, producing final color, depth, and other outputs.

Workflow: A vertex shader processes vertices; the rasterizer generates fragments with interpolated data such as normals and texture coordinates; the fragment shader then executes per fragment to compute lighting, sample textures, apply material properties, and output color.

Applications: Per-pixel shading supports lighting models like Phong and Blinn-Phong, normal mapping, and texture mapping. It is central to physically based rendering in the fragment stage, and enables features such as shadows via shadow maps and various screen-space effects.

Comparison to per-vertex shading: Per-pixel shading yields more accurate results and fewer interpolation artifacts than per-vertex shading (Gouraud shading) because lighting calculations are performed at the pixel level. It is more computationally intensive since the shader runs for many fragments per frame.

Languages and platforms: Fragment shaders are written in languages such as GLSL, HLSL, or Metal Shading Language and run on GPUs across APIs like OpenGL, DirectX, Vulkan, and WebGL.

Performance considerations: The cost of fragment shader per-pixel shading scales with shader complexity, texture fetches, and memory bandwidth. Optimization strategies include reducing texture lookups, using simpler lighting models where appropriate, employing early depth testing, and leveraging multi-sampling and LOD. fragmentshaderperpixel remains a foundational concept in modern real-time rendering.