Shaders

Shaders are programs that are run on the GPU when processing a certain unit of rendering, usually vertices or pixels/fragments; they allow rendering programmers to manipulate their rendering output in any way they see fit.

While shaders, as the name implies, were originally conceived to allow different kinds of lighting/shading calculations, today they're used for a variety of things from lighting calculation through stylized rendering to 2D compositing or post-processing, and even complex geometry manipulations and particle effects.

Types of shaders:

• Compute
• Fragment
• Geometry
• Tessellation
• Vertex

Key concepts:

• FBO (framebuffer object)
• GPGPU (general-purpose computing on GPUs) - the concept of using the GPU to perform computation
• Ping pong - technique in which the output texture of one shader is fed to another shader as an input, sometimes cycling back and forth multiple times. The final texture gets sent to the display, then the shaders are swapped so that the most recent output becomes the input to the next iteration.
• Render to texture (RTT) - instead of rendering a scene to the screen, in this technique it is rendered to an "offscreen" texture that can be reused later.
• Shading language
• Textures
• Uniform - a type qualifier indicating a read-only variable passed to a shader from the CPU side of the program. These values will not change within a draw call, and are available to every shader that declares it.
• Varying - a type qualifier indicating a variable that can change within the vertex shader, then passed to the fragment shader as a read-only value.

Languages:

• Cg - shading language developed by Nvidia in close collaboration with Microsoft
• CUDA - parallel computing API that makes it easier to use GPGPU for complicated tasks
• GLSL (OpenGL Shading Language) - shading language used by OpenGL
• HLSL (High-Level Shading Language) - shading language used by DirectX

Articles:

• The Book of Shaders by Patricio Gonzalez Vivo and Jen Lowe
• Shaders by Learn OpenGL
• GLSL Shaders on MDN web docs
• Shaders (Processing) tutorial by Andres Colubi
• Introducing Shaders (openFrameworks) by Lucasz Karluk, Joshua Noble, Jordi Puig
• Shader modules (Vulkan)

Code tools:

• Bonzomatic
• glslsandbox
• RenderMonkey
• Shadertoy

Videos:

• Shader Coding seminar at Revision 2019

Art of Code