shader()

Sets the p5.Shader object to apply while drawing.

Shaders are programs that run on the graphics processing unit (GPU). They can process many pixels or vertices at the same time, making them fast for many graphics tasks. They’re written in a language called GLSL and run along with the rest of the code in a sketch. p5.Shader objects can be created using the createShader() and loadShader() functions.

The parameter, s, is the p5.Shader object to apply. For example, calling shader(myShader) applies myShader to process each pixel on the canvas. The shader will be used for:

• Fills when a texture is enabled if it includes a uniform sampler2D.
• Fills when lights are enabled if it includes the attribute aNormal, or if it has any of the following uniforms: uUseLighting, uAmbientLightCount, uDirectionalLightCount, uPointLightCount, uAmbientColor, uDirectionalDiffuseColors, uDirectionalSpecularColors, uPointLightLocation, uPointLightDiffuseColors, uPointLightSpecularColors, uLightingDirection, or uSpecular.
• Fills whenever there are no lights or textures.
• Strokes if it includes the uniform uStrokeWeight.

The source code from a p5.Shader object's fragment and vertex shaders will be compiled the first time it's passed to shader(). See MDN for more information about compiling shaders.

Calling resetShader() restores a sketch’s default shaders.

Note: Shaders can only be used in WebGL mode.