Inputs and outputs is the code before GLSL that defines what inputs and outputs are made for the shader, these can be the following

Inputs

• uniform sampler2D - Images that need to be read by the shader. They show up as input connectors on the node.
• uniform float - single float values
• uniform vec2 - vector with two elements
• uniform vec3 - vector with three elements
• uniform vec4 - vector with four elements

<aside> 💡 The use of the word 'uniform' is optional

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Outputs

• out vec4 - image with four channels

Metadata

Inputs (samplers and non-sampler uniforms) can have metadata attached to it, in the form of JSON key-value pairs enclosed in braces at the end of a declaration, before the semicolon.

There are different kinds of metadata for input types, summarized below:

Sampler states

uniform sampler2Dinputs can have sampler state information attached to it, in the form of JSON key-value pairs:

uniform sampler2D colorInput {
	"addressU": "CLAMP",
	"addressV": "CLAMP",
	"addressW": "CLAMP",
	"minFilter": "LINEAR",
	"magFilter": "LINEAR"
};

The following keys are recognized:

• addressU, addressV, addressW: texture addressing mode for the U/V/W coordinate.
  • REPEAT: see GL_REPEAT
  • CLAMP: see GL_CLAMP_TO_EDGE
  • BORDER: see GL_CLAMP_TO_BORDER
  • MIRROR: see GL_MIRRORED_REPEAT