1 files changed, 74 insertions, 0 deletions
diff --git a/libs/moonshine/scanlines.lua b/libs/moonshine/scanlines.lua
new file mode 100644
index 0000000..fb5423d
--- /dev/null
+++ b/libs/moonshine/scanlines.lua
@@ -0,0 +1,74 @@
+--[[
+Public domain:
+
+Copyright (C) 2017 by Matthias Richter <vrld@vrld.org>
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+PERFORMANCE OF THIS SOFTWARE.
+]]--
+
+return function(moonshine)
+  local shader = love.graphics.newShader[[
+    extern number width;
+    extern number phase;
+    extern number thickness;
+    extern number opacity;
+    extern vec3 color;
+    vec4 effect(vec4 c, Image tex, vec2 tc, vec2 _) {
+      number v = .5*(sin(tc.y * 3.14159 / width * love_ScreenSize.y + phase) + 1.);
+      c = Texel(tex,tc);
+      //c.rgb = mix(color, c.rgb, mix(1, pow(v, thickness), opacity));
+      c.rgb -= (color - c.rgb) * (pow(v,thickness) - 1.0) * opacity;
+      return c;
+    }]]
+
+
+  local defaults = {
+    width = 2,
+    phase = 0,
+    thickness = 1,
+    opacity = 1,
+    color = {0,0,0},
+  }
+
+  local setters = {}
+  setters.width = function(v)
+    shader:send("width", tonumber(v) or defaults.width)
+  end
+  setters.frequency = function(v)
+    shader:send("width", love.graphics.getHeight()/(tonumber(v) or love.graphics.getHeight()))
+  end
+  setters.phase = function(v)
+    shader:send("phase", tonumber(v) or defaults.phase)
+  end
+  setters.thickness = function(v)
+    shader:send("thickness", math.max(0, tonumber(v) or defaults.thickness))
+  end
+  setters.opacity = function(v)
+    shader:send("opacity", math.min(1, math.max(0, tonumber(v) or defaults.opacity)))
+  end
+  setters.color = function(c)
+    assert(type(c) == "table" and #c == 3, "Invalid value for `color'")
+    assert(c[1] <= 1, "Colors should be normalized in [0,1]")
+    shader:send("color", {
+      (tonumber(c[1]) or defaults.color[1]),
+      (tonumber(c[2]) or defaults.color[2]),
+      (tonumber(c[3]) or defaults.color[3])
+    })
+  end
+
+  return moonshine.Effect{
+    name = "scanlines",
+    shader = shader,
+    setters = setters,
+    defaults = defaults,
+  }
+end