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####################
Connecting With Lua
####################
Overview
########
Every shader that is marked as ``dynamic`` can be controlled through the Lua scripting system. Shaders can be disabled and enabled,
and their uniforms can be controlled via scripts. For details, reference the API documentation :doc:`here<../lua-scripting/openmw_postprocessing>`.
Toggling Shaders With a Keybind
###############################
In this example, we use the desaturation shader created in the previous section and bind the ``x`` key to toggle it on and off.
It is assumed the shader has the filename ``desaturate.omwfx`` in this example.
.. code-block:: none
uniform_float uDesaturationFactor {
default = 0.5;
min = 0.0;
max = 1.0;
step = 0.05;
description = "Desaturation factor. A value of 1.0 is full grayscale.";
}
fragment desaturate {
omw_In vec2 omw_TexCoord;
void main()
{
// fetch scene texture from last shader
vec4 scene = omw_GetLastShader(omw_TexCoord);
// desaturate RGB component
const vec3 luminance = vec3(0.299, 0.587, 0.144);
float gray = dot(luminance, scene.rgb);
omw_FragColor = vec4(mix(scene.rgb, vec3(gray), uDesaturationFactor), scene.a);
}
}
technique {
description = "Desaturates scene";
version = "1.0";
author = "Fargoth";
passes = desaturate;
dynamic = true;
}
.. note::
The ``dynamic`` flag here is very important, otherwise Lua will not be able to interact with this shader.
Next, a script that is attached to the player is needed. The shader is loaded first, then toggled on and off in response to key presses.
Below is a working example to illustrate this.
.. code-block:: Lua
local input = require('openmw.input')
local postprocessing = require('openmw.postprocessing')
local shader = postprocessing.load('desaturate')
return {
engineHandlers = {
onKeyPress = function(key)
if key.code == input.KEY.X then
if shader:isEnabled() then
shader:disable()
else
shader:enable()
end
end
end
}
}
Hiding Shader From the HUD
##########################
If the HUD is opened (default with ``F2``) you will notice it lists all available shaders. If you want your shader to be completely
hidden in this HUD, this can done by adding the ``hidden`` flag to the main technique block.
.. code-block:: none
technique {
description = "Desaturates scene";
version = "1.0";
author = "Fargoth";
passes = desaturate;
flags = hidden;
dynamic = true;
}
This flag is usually used when the shader is associated with something special, like special weather, spell, or alcohol effects.
Controlling Uniforms
####################
By default, any uniform you defined will not be exposed to Lua, you must set the ``static`` flag to ``false`` in every uniform block for which you want exposed.
For example, to set the ``uDesaturationFactor`` uniform from a Lua script, we must define it as follows.
.. code-block:: none
uniform_float uDesaturationFactor {
default = 0.5;
min = 0.0;
max = 1.0;
step = 0.05;
description = "Desaturation factor. A value of 1.0 is full grayscale.";
static = false;
}
In some player Lua script, this uniform can then be freely set. When a uniform is set to ``static`` it will no longer show up in the HUD.
Here, instead of disabling and enabling the shader we set the factor to ``0`` or ``1``, respectively.
.. code-block:: Lua
local input = require('openmw.input')
local postprocessing = require('openmw.postprocessing')
local shader = postprocessing.load('desaturate')
local factor = 0
return {
engineHandlers = {
onKeyPress = function(key)
if key.code == input.KEY.X then
if factor == 0 then
factor = 1
else
factor = 0
end
shader:setFloat('uDesaturationFactor', factor)
end
end
}
}
|
