# HG changeset patch
# User Michael Pavone <pavone@retrodev.com>
# Date 1496596056 25200
# Node ID 4942da15919419cee31eddc8c58a85e5e953449c
# Parent  99d153d9e9ca737abfdefabfe7ca0707186e8c96
Added a "subtle" CRT shader contributed by Anael Seghezzi

diff -r 99d153d9e9ca -r 4942da159194 shaders/crt.f.glsl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/shaders/crt.f.glsl	Sun Jun 04 10:07:36 2017 -0700
@@ -0,0 +1,89 @@
+#version 110
+
+/* Subtle CRT shader usable in fullscreen - Anaël Seghezzi [anael(at)maratis3d.com]
+   This shader is free software distributed under the terms of the GNU General Public
+   License version 3 or higher. This gives you the right to redistribute and/or
+   modify the program as long as you follow the terms of the license. See the file
+   COPYING for full license details.
+*/
+
+#define M_PI 3.14159265358979323846
+
+uniform sampler2D textures[2];
+uniform float width, height;
+varying vec2 texcoord;
+varying vec2 screencoord;
+
+
+float nrand(vec2 n) {
+	return fract(sin(dot(n.xy, vec2(12.9898, 78.233))) * 43758.5453);
+}
+
+float scanline(vec2 texco)
+{
+	return (1.0 - abs(cos(texco.y * 512.0 * M_PI)));
+}
+
+vec2 sharp_coord(vec2 texco, vec2 dim, vec2 sharpness)
+{
+	vec2 texcoif = texco * dim;
+	vec2 texcoi = floor(texcoif);
+	vec2 mu = (texcoif - 0.5) - texcoi;
+	vec2 mub = pow(abs(mu) * 2.0, sharpness) * sign(mu) * 0.5;
+	return (texcoi + mub + 0.5) / dim;	
+}
+
+void main()
+{
+	float v = 1.0 / 512.0;
+	float yforce = 0.175;
+	float vign = length(screencoord);
+
+	// monitor deformation
+	vec2 monitorcoord = (screencoord + screencoord * vign * 0.025);
+	
+	if (monitorcoord.x < -1.0 || monitorcoord.y < -1.0 || monitorcoord.x > 1.0 || monitorcoord.y > 1.0) {
+		gl_FragColor = vec4(0.0);
+		return;
+	}
+
+	vec2 texco = monitorcoord * vec2(width/1024.0, height/-1024.0) + vec2(width/1024.0, height/1024.0);
+
+	// mask
+	float maskx = 1.0 - pow(monitorcoord.x, 200.0);
+	float masky = 1.0 - pow(-monitorcoord.y, 200.0);
+	float mask = clamp(maskx * masky, 0.0, 1.0);
+
+	// sharp texcoord
+	vec2 texco_sharp0 = sharp_coord(texco, vec2(512.0, 512.0), vec2(4.0, 8.0));
+	vec2 texco_sharp1 = sharp_coord(texco - vec2(0.0, 1.0 / 1024.0), vec2(512.0, 512.0), vec2(4.0, 8.0));
+
+	vec4 src0 = texture2D(textures[0], texco_sharp0);
+	vec4 src1 = texture2D(textures[1], texco_sharp1);
+
+	// interlace mix
+	float interlace = cos((texco.y * 1024.0) * M_PI);
+	vec4 src_mix = mix(src0, src1, interlace * 0.5 + 0.5);
+
+	// blur
+	vec4 src_blur = mix(texture2D(textures[0], texco), texture2D(textures[1], texco), 0.5);
+
+#ifdef NO_SCANLINE
+
+	gl_FragColor = (src_mix * 0.95 + (src_blur * (1.6 - vign * 0.4) * 0.1)) * mask;
+
+#else
+	// multisample scanline with grain
+	// TODO: offset grain with time (needs a "frame" uniform)
+	float cosy;
+	cosy  = scanline(texco + vec2(0.125, v * (nrand(texcoord + vec2(0.0, 1.0)) * 0.25) + 0.3333));
+	cosy += scanline(texco + vec2(0.25, v * (nrand(texcoord + vec2(0.0, 2.0)) * 0.25) + 0.25));
+	cosy += scanline(texco + vec2(0.50, v * (nrand(texcoord + vec2(0.0, 3.0)) * 0.25) + 0.6666));
+	cosy += scanline(texco + vec2(0.75, v * (nrand(texcoord + vec2(0.0, 4.0)) * 0.25) + 0.75));
+	cosy *= 0.25;
+
+	// final scanline + burn
+	gl_FragColor = ((src_mix * ((1.0 - yforce) + cosy * yforce)) + (src_blur * (1.6 - vign * 0.4) * 0.1)) * mask;
+
+#endif
+}
\ No newline at end of file
diff -r 99d153d9e9ca -r 4942da159194 shaders/crt.v.glsl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/shaders/crt.v.glsl	Sun Jun 04 10:07:36 2017 -0700
@@ -0,0 +1,13 @@
+#version 110
+
+attribute vec2 pos;
+varying vec2 texcoord;
+varying vec2 screencoord;
+uniform float width, height;
+
+void main()
+{
+	gl_Position = vec4(pos, 0.0, 1.0);
+	texcoord = sign(pos) * vec2(width/1024.0, height/-1024.0) + vec2(width/1024.0, height/1024.0);
+	screencoord = sign(pos);
+}
\ No newline at end of file