Shader
A Shader is a piece of code that runs on the Graphics Processing Unit (GPU) to perform graphical computations, most commonly in the context of 3D graphics rendering. Shaders are essential for defining the visual characteristics of computer graphics, allowing for complex effects like lighting, shadows, texture mapping, and more.
History
- Early Days: Initially, graphics were rendered using fixed-function pipelines where the hardware performed predefined operations. Shaders emerged as a way to make these operations programmable.
- Introduction of Programmable Shaders: With the advent of DirectX 8 in 2000, Microsoft introduced the concept of vertex and pixel shaders, which allowed for more flexible manipulation of vertices and pixels.
- Evolution: Over time, shader technology evolved:
- OpenGL ARB Assembly Language: Before high-level shading languages, shaders were written in assembly-like languages.
- HLSL and GLSL: High-Level Shading Language (HLSL) for DirectX and OpenGL Shading Language (GLSL) were developed to make shader programming more accessible.
- Unified Shader Model: With DirectX 10 and OpenGL 3.3, the concept of unified shaders was introduced where all shader types share the same hardware resources.
Types of Shaders
- Vertex Shader: Processes each vertex's data, transforming vertex positions from model space to clip space, and can also alter attributes like color, texture coordinates, and normals.
- Pixel (Fragment) Shader: Determines the color of each pixel or fragment based on various inputs like textures, lighting, and materials.
- Geometry Shader: Operates on entire primitives (like triangles or points) and can generate new primitives from the original ones.
- Tessellation Shaders: (Hull and Domain Shaders) Used for subdividing geometry to enhance detail in real-time rendering.
- Compute Shader: A general-purpose shader for performing calculations on the GPU, not necessarily related to rendering.
Context and Usage
Shaders are used in:
- Video Games: For real-time rendering of environments, characters, effects, etc.
- Film and Visual Effects: To achieve realistic or stylized visuals in post-production.
- Virtual Reality: For creating immersive 3D environments.
- Scientific Visualization: To represent complex data sets visually.
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