Fragment Shader
===============

The :doc:`/types/Renderable/index` :doc:`/entity_component_system/component/index` accepts custom fragment shaders.

These fragment shaders are written in GLSL and have some special variables.

Inputs
------

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	:class: code-table

	* - Name
	  - Type
	  - Description
	* - NtshEngn_position
	  - vec3
	  - The fragment's position, in **world-space**.
	* - NtshEngn_normal
	  - vec3
	  - The fragment's normal.
	* - NtshEngn_tangent
	  - vec3
	  - The fragment's tangent.
	* - NtshEngn_bitangent
	  - vec3
	  - The fragment's bitangent.
	* - NtshEngn_uv
	  - vec2
	  - The fragment's texture coordinates.
	* - NtshEngn_tbn
	  - mat3
	  - The fragment's Tangent-Bitangent-Normal matrix.
	* - NtshEngn_diffuseTextureSampler
	  - sampler2D
	  - The object's material's diffuse texture.
	* - NtshEngn_normalTextureSampler
	  - sampler2D
	  - The object's material's normal texture.
	* - NtshEngn_metalnessTextureSampler
	  - sampler2D
	  - The object's material's metalness texture.
	* - NtshEngn_roughnessTextureSampler
	  - sampler2D
	  - The object's material's roughness texture.
	* - NtshEngn_occlusionTextureSampler
	  - sampler2D
	  - The object's material's occlusion texture.
	* - NtshEngn_emissiveTextureSampler
	  - sampler2D
	  - The object's material's emissive texture.
	* - NtshEngn_emissiveFactor
	  - float
	  - The object's material's metalness factor.
	* - NtshEngn_alphaCutoff
	  - float
	  - The object's material's alpha cutoff.
	* - NtshEngn_scaleUV
	  - vec2
	  - The object's material's UV scale.
	* - NtshEngn_offsetUV
	  - vec2
	  - The object's material's UV offset.
	* - NtshEngn_useTriplanarMapping
	  - bool
	  - ``true`` if the object's material uses triplanar mapping, else, ``false``.
	* - NtshEngn_directionalLightCount
	  - uint
	  - The number of directional lights in the scene.
	* - NtshEngn_directionalLight(i)
	  - :doc:`/types/Light/index`
	  - The *i*th directional light.
	* - NtshEngn_pointLightCount
	  - uint
	  - The number of point lights in the scene.
	* - NtshEngn_pointLight(i)
	  - :doc:`/types/Light/index`
	  - The *i*th point light.
	* - NtshEngn_spotLightCount
	  - uint
	  - The number of spot lights in the scene.
	* - NtshEngn_spotLight(i)
	  - :doc:`/types/Light/index`
	  - The *i*th spot light.
	* - NtshEngn_ambientLightCount
	  - uint
	  - The number of ambient lights in the scene.
	* - NtshEngn_ambientLight(i)
	  - :doc:`/types/Light/index`
	  - The *i*th ambient light.
	* - NtshEngn_time
	  - float
	  - The time since the application's launch, in **seconds**.
	* - NtshEngn_cameraPosition
	  - vec3
	  - The camera's position, in **world-space**.
	* - NtshEngn_useReversedDepth
	  - bool
	  - ``true`` if the graphics module uses reversed depth (*1* is close, *0* is far), else, ``false`` (*0* is close, *1* is far).

Outputs
-------

.. list-table::
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	:header-rows: 1
	:class: code-table

	* - Name
	  - Type
	  - Description
	* - NtshEngn_outColor
	  - vec4
	  - The output color.
	* - NtshEngn_outDepth
	  - float
	  - The output depth.