Vertexshaders

Vertex shaders are programmable stages in modern graphics pipelines responsible for processing individual vertices. They replace fixed-function vertex processing with programmable shading, running on the GPU and executed once per vertex before rasterization. Vertex shaders receive per-vertex attributes such as position, normal, color, texture coordinates, bone weights, and other data supplied by the application or previous pipeline stages. They also receive uniform variables from the application, including transformation matrices (model, view, projection), lighting parameters, and material properties.

The primary role of a vertex shader is to transform vertex positions from object space to clip space, typically by applying the model-view-projection transformation. It may also compute per-vertex lighting, generate or modify per-vertex attributes, and perform skinning for animated characters. After processing, the vertex shader outputs data to the next stage, most importantly the final clip-space position (often via a dedicated output variable), as well as other interpolated data to be passed to the fragment shader, such as texture coordinates or lighting terms.

In modern graphics APIs such as OpenGL, Direct3D, Vulkan, and Metal, vertex shaders are written in shading languages such as GLSL, HLSL, SPIR-V, or Metal Shading Language. They form part of a programmable pipeline that can also include geometry shaders and tessellation shaders, though many applications rely primarily on vertex and fragment shaders. Performance considerations include minimizing per-vertex computation, ensuring efficient memory access, and correctly using interpolation qualifiers to minimize bandwidth and maximize throughput.

Vertex shading is foundational to 3D rendering, providing the first programmable stage and enabling essential transformations and effects before fragments are produced.