60 lines
1.9 KiB
Lua
60 lines
1.9 KiB
Lua
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--[[
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Public domain:
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Copyright (C) 2017 by Matthias Richter <vrld@vrld.org>
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shader based on code by sam hocevar, see
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https://gamedev.stackexchange.com/questions/59797/glsl-shader-change-hue-saturation-brightness
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Permission to use, copy, modify, and/or distribute this software for any
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purpose with or without fee is hereby granted.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
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FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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PERFORMANCE OF THIS 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 num_bands;
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vec3 rgb2hsv(vec3 c)
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{
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vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
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vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));
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vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));
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float d = q.x - min(q.w, q.y);
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float e = 1.0e-10;
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return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x);
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}
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vec3 hsv2rgb(vec3 c)
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{
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vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
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vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
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return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
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}
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vec4 effect(vec4 color, Image texture, vec2 tc, vec2 _)
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{
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color = Texel(texture, tc);
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vec3 hsv = floor((rgb2hsv(color.rgb) * num_bands) + vec3(0.5)) / num_bands;
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return vec4(hsv2rgb(hsv), color.a);
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}]]
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return moonshine.Effect{
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name = "posterize",
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shader = shader,
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setters = {
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num_bands = function(v)
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shader:send("num_bands", math.max(1, tonumber(v) or 1))
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end
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},
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defaults = {num_bands = 3}
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}
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end
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