mirror of
https://github.com/godotengine/godot-docs.git
synced 2026-01-07 02:12:07 +03:00
80 lines
6.0 KiB
ReStructuredText
80 lines
6.0 KiB
ReStructuredText
.. _doc_fog_shader:
|
|
|
|
Fog shaders
|
|
===========
|
|
|
|
Fog shaders are used to define how fog is added (or subtracted) from a scene in
|
|
a given area. Fog shaders are always used together with
|
|
:ref:`FogVolumes <class_FogVolume>` and volumetric fog. Fog shaders only have
|
|
one processing function, the ``fog()`` function.
|
|
|
|
The resolution of the fog shaders depends on the resolution of the
|
|
volumetric fog froxel grid. Accordingly, the level of detail that a fog shader
|
|
can add depends on how close the :ref:`FogVolume <class_FogVolume>` is to the
|
|
camera.
|
|
|
|
Fog shaders are a special form of compute shader that is called once for
|
|
every froxel that is touched by an axis aligned bounding box of the associated
|
|
:ref:`FogVolume <class_FogVolume>`. This means that froxels that just barely
|
|
touch a given :ref:`FogVolume <class_FogVolume>` will still be used.
|
|
|
|
Built-ins
|
|
^^^^^^^^^
|
|
|
|
Values marked as "in" are read-only. Values marked as "out" are for optional
|
|
writing and will not necessarily contain sensible values. Samplers cannot be
|
|
written to so they are not marked.
|
|
|
|
|
|
Global built-ins
|
|
^^^^^^^^^^^^^^^^
|
|
|
|
Global built-ins are available everywhere, including in custom functions.
|
|
|
|
|
|
+---------------------------------+-----------------------------------------------------------------------------------------+
|
|
| Built-in | Description |
|
|
+=================================+=========================================================================================+
|
|
| in float **TIME** | Global time, in seconds. |
|
|
+---------------------------------+-----------------------------------------------------------------------------------------+
|
|
| in float **PI** | A ``PI`` constant (``3.141592``). |
|
|
| | A ratio of a circle's circumference to its diameter and amount of radians in half turn. |
|
|
+---------------------------------+-----------------------------------------------------------------------------------------+
|
|
| in float **TAU** | A ``TAU`` constant (``6.283185``). |
|
|
| | An equivalent of ``PI * 2`` and amount of radians in full turn. |
|
|
+---------------------------------+-----------------------------------------------------------------------------------------+
|
|
| in float **E** | A ``E`` constant (``2.718281``). |
|
|
| | Euler's number and a base of the natural logarithm. |
|
|
+---------------------------------+-----------------------------------------------------------------------------------------+
|
|
|
|
Fog built-ins
|
|
^^^^^^^^^^^^^
|
|
|
|
All of the output values of fog volumes overlap one another. This allows
|
|
:ref:`FogVolumes <class_FogVolume>` to be rendered efficiently as they can all
|
|
be drawn at once.
|
|
|
|
+-------------------------------+-------------------------------------------------------------------------------------------------+
|
|
| Built-in | Description |
|
|
+===============================+=================================================================================================+
|
|
| in vec3 **WORLD_POSITION** | Position of current froxel cell in world space. |
|
|
+-------------------------------+-------------------------------------------------------------------------------------------------+
|
|
| in vec3 **OBJECT_POSITION** | Position of the center of the current :ref:`FogVolume <class_FogVolume>` in world space. |
|
|
+-------------------------------+-------------------------------------------------------------------------------------------------+
|
|
| in vec3 **UVW** | 3-dimensional uv, used to map a 3D texture to the current :ref:`FogVolume <class_FogVolume>`. |
|
|
+-------------------------------+-------------------------------------------------------------------------------------------------+
|
|
| in vec3 **EXTENTS** | Color value of corresponding pixel from half resolution pass. Uses linear filter. |
|
|
+-------------------------------+-------------------------------------------------------------------------------------------------+
|
|
| in vec3 **SDF** | Signed distance field to the surface of the :ref:`FogVolume <class_FogVolume>`. Negative if |
|
|
| | inside volume, positive otherwise. |
|
|
+-------------------------------+-------------------------------------------------------------------------------------------------+
|
|
| out vec3 **ALBEDO** | Output base color value, interacts with light to produce final color. Only written to fog |
|
|
| | volume if used. |
|
|
+-------------------------------+-------------------------------------------------------------------------------------------------+
|
|
| out float **DENSITY** | Output density value. Can be negative to allow subtracting one volume from another. Density |
|
|
| | must be used for fog shader to write anything at all. |
|
|
+-------------------------------+-------------------------------------------------------------------------------------------------+
|
|
| out vec3 **EMISSION** | Output emission color value, added to color during light pass to produce final color. Only |
|
|
| | written to fog volume if used. |
|
|
+-------------------------------+-------------------------------------------------------------------------------------------------+
|