107 lines
3.2 KiB
Lua
107 lines
3.2 KiB
Lua
--[[
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The MIT License (MIT)
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Original code: Copyright (c) 2015 Josef Patoprsty
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Port to moonshine: Copyright (c) 2017 Matthias Richter <vrld@vrld.org>
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Based on work by: ioxu
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https://www.love2d.org/forums/viewtopic.php?f=4&t=3733&start=120#p71099
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Based on work by: Fabien Sanglard
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http://fabiensanglard.net/lightScattering/index.php
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Based on work from:
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[Mitchell]: Kenny Mitchell "Volumetric Light Scattering as a Post-Process" GPU Gems 3 (2005).
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[Mitchell2]: Jason Mitchell "Light Shaft Rendering" ShadersX3 (2004).
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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]]--
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return function(moonshine)
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local shader = love.graphics.newShader[[
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extern number exposure;
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extern number decay;
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extern number density;
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extern number weight;
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extern vec2 light_position;
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extern number samples;
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vec4 effect(vec4 color, Image tex, vec2 uv, vec2 px) {
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color = Texel(tex, uv);
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vec2 offset = (uv - light_position) * density / samples;
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number illumination = decay;
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vec4 c = vec4(.0, .0, .0, 1.0);
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for (int i = 0; i < int(samples); ++i) {
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uv -= offset;
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c += Texel(tex, uv) * illumination * weight;
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illumination *= decay;
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}
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return vec4(c.rgb * exposure + color.rgb, color.a);
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}]]
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local setters, light_position = {}
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for _,k in ipairs{"exposure", "decay", "density", "weight"} do
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setters[k] = function(v)
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shader:send(k, math.min(1, math.max(0, tonumber(v) or 0)))
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end
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end
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setters.light_position = function(v)
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light_position = {unpack(v)}
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shader:send("light_position", v)
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end
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setters.light_x = function(v)
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assert(type(v) == "number", "Invalid value for `light_x'")
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setters.light_position{v, light_position[2]}
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end
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setters.light_y = function(v)
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assert(type(v) == "number", "Invalid value for `light_y'")
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setters.light_position{light_position[1], v}
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end
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setters.samples = function(v)
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shader:send("samples", math.max(1,tonumber(v) or 1))
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end
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local defaults = {
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exposure = 0.25,
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decay = 0.95,
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density = 0.15,
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weight = 0.5,
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light_position = {0.5,0.5},
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samples = 70
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}
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return moonshine.Effect{
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name = "godsray",
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shader = shader,
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setters = setters,
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defaults = defaults
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}
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end
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