Mercurial > repos > blastem

annotate shaders/ntsc.f.glsl @ 2410:f1574b22d5d9

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Update Sik's NTSC shader
author Michael Pavone <pavone@retrodev.com>
date Thu, 04 Jan 2024 22:12:03 -0800
parents 49bd818ec9d8
children 9f3008f91bec
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
2329
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
1 //******************************************************************************
2410
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
2 // NTSC composite simulator for BlastEm, fixed rainbow frequency edition
2329
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
3 // Shader by Sik, based on BlastEm's default shader
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
4 //
2410
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
5 // Now with gamma correction (NTSC = 2.5 gamma, sRGB = 2.2 gamma*)
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
6 // *sorta, sRGB isn't exactly a gamma curve, but close enough
2343
49bd818ec9d8 Updated NTSC shader from Sik
Michael Pavone <pavone@retrodev.com>
parents: 2329
diff changeset
7 //
2329
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
8 // It works by converting from RGB to YIQ and then encoding it into NTSC, then
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
9 // trying to decode it back. The lossy nature of the encoding process results in
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
10 // the rainbow effect. It also accounts for the differences between H40 and H32
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
11 // mode as it computes the exact colorburst cycle length.
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
12 //
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
13 // This shader tries to work around the inability to keep track of previous
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
14 // pixels by sampling seven points (in 0.25 colorburst cycle intervals), that
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
15 // seems to be enough to give decent filtering (four samples are used for
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
16 // low-pass filtering, but we need seven because decoding chroma also requires
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
17 // four samples so we're filtering over overlapping samples... just see the
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
18 // comments in the I/Q code to understand).
2410
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
19 //
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
20 // Thanks to Tulio Adriano for helping adjust the frequency of the banding.
2329
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
21 //******************************************************************************
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
22
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
23 uniform mediump float width;
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
24 uniform sampler2D textures[2];
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
25 uniform mediump vec2 texsize;
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
26 varying mediump vec2 texcoord;
2410
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
27 uniform int curfield;
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
28 uniform int scanlines;
2329
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
29
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
30 // Converts from RGB to YIQ
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
31 mediump vec3 rgba2yiq(vec4 rgba)
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
32 {
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
33 return vec3(
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
34 rgba[0] * 0.3 + rgba[1] * 0.59 + rgba[2] * 0.11,
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
35 rgba[0] * 0.599 + rgba[1] * -0.2773 + rgba[2] * -0.3217,
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
36 rgba[0] * 0.213 + rgba[1] * -0.5251 + rgba[2] * 0.3121
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
37 );
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
38 }
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
39
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
40 // Encodes YIQ into composite
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
41 mediump float yiq2raw(vec3 yiq, float phase)
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
42 {
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
43 return yiq[0] + yiq[1] * sin(phase) + yiq[2] * cos(phase);
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
44 }
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
45
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
46 // Converts from YIQ to RGB
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
47 mediump vec4 yiq2rgba(vec3 yiq)
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
48 {
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
49 return vec4(
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
50 yiq[0] + yiq[1] * 0.9469 + yiq[2] * 0.6236,
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
51 yiq[0] - yiq[1] * 0.2748 - yiq[2] * 0.6357,
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
52 yiq[0] - yiq[1] * 1.1 + yiq[2] * 1.7,
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
53 1.0
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
54 );
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
55 }
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
56
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
57 void main()
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
58 {
2410
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
59 // The coordinate of the pixel we're supposed to access
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
60 // In interlaced mode, the entire screen is shifted down by half a scanline,
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
61 // y_offset is used to account for this.
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
62 mediump float y_offset = float(curfield) * -0.5 / texsize.y;
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
63 mediump float x = texcoord.x;
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
64 mediump float y = texcoord.y + y_offset;
2329
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
65
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
66 // Horizontal distance of half a colorburst cycle
2410
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
67 mediump float factorX = (1.0 / texsize.x) / 170.667 * 0.5 * width;
2329
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
68
2410
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
69 // sRGB approximates a gamma ramp of 2.2 while NTSC has a gamma of 2.5
2343
49bd818ec9d8 Updated NTSC shader from Sik
Michael Pavone <pavone@retrodev.com>
parents: 2329
diff changeset
70 // Use this value to do gamma correction of every RGB value
49bd818ec9d8 Updated NTSC shader from Sik
Michael Pavone <pavone@retrodev.com>
parents: 2329
diff changeset
71 mediump float gamma = 2.5 / 2.2;
49bd818ec9d8 Updated NTSC shader from Sik
Michael Pavone <pavone@retrodev.com>
parents: 2329
diff changeset
72
2329
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
73 // Where we store the sampled pixels.
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
74 // [0] = current pixel
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
75 // [1] = 1/4 colorburst cycles earlier
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
76 // [2] = 2/4 colorburst cycles earlier
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
77 // [3] = 3/4 colorburst cycles earlier
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
78 // [4] = 1 colorburst cycle earlier
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
79 // [5] = 1 1/4 colorburst cycles earlier
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
80 // [6] = 1 2/4 colorburst cycles earlier
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
81 mediump float phase[7]; // Colorburst phase (in radians)
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
82 mediump float raw[7]; // Raw encoded composite signal
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
83
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
84 // Sample all the pixels we're going to use
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
85 for (int n = 0; n < 7; n++, x -= factorX * 0.5) {
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
86 // Compute colorburst phase at this point
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
87 phase[n] = x / factorX * 3.1415926;
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
88
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
89 // Decode RGB into YIQ and then into composite
2410
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
90 raw[n] = yiq2raw(rgba2yiq(
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
91 texture2D(textures[curfield], vec2(x, y))
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
92 ), phase[n]);
2329
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
93 }
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
94
2410
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
95 // Decode Y by averaging over the last whole sampled cycle (effectively
2329
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
96 // filtering anything above the colorburst frequency)
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
97 mediump float y_mix = (raw[0] + raw[1] + raw[2] + raw[3]) * 0.25;
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
98
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
99 // Decode I and Q (see page below to understand what's going on)
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
100 // https://codeandlife.com/2012/10/09/composite-video-decoding-theory-and-practice/
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
101 //
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
102 // Retrieving I and Q out of the raw signal is done like this
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
103 // (use sin for I and cos for Q):
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
104 //
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
105 // 0.5 * raw[0] * sin(phase[0]) + 0.5 * raw[1] * sin(phase[1]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
106 // 0.5 * raw[2] * sin(phase[2]) + 0.5 * raw[3] * sin(phase[3])
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
107 //
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
108 // i.e. multiply each of the sampled quarter cycles against the reference
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
109 // wave and average them (actually double that because for some reason
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
110 // that's needed to get the correct scale, hence 0.5 instead of 0.25)
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
111 //
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
112 // That turns out to be blocky tho, so we opt to filter down the chroma...
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
113 // which requires doing the above *four* times if we do it the same way as
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
114 // we did for luminance (note that 0.125 = 1/4 of 0.5):
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
115 //
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
116 // 0.125 * raw[0] * sin(phase[0]) + 0.125 * raw[1] * sin(phase[1]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
117 // 0.125 * raw[2] * sin(phase[2]) + 0.125 * raw[3] * sin(phase[3]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
118 // 0.125 * raw[1] * sin(phase[1]) + 0.125 * raw[2] * sin(phase[2]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
119 // 0.125 * raw[3] * sin(phase[3]) + 0.125 * raw[4] * sin(phase[4]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
120 // 0.125 * raw[2] * sin(phase[2]) + 0.125 * raw[3] * sin(phase[3]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
121 // 0.125 * raw[4] * sin(phase[4]) + 0.125 * raw[5] * sin(phase[5]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
122 // 0.125 * raw[3] * sin(phase[3]) + 0.125 * raw[4] * sin(phase[4]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
123 // 0.125 * raw[5] * sin(phase[5]) + 0.125 * raw[6] * sin(phase[6])
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
124 //
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
125 // There are a lot of repeated values there that could be merged into one,
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
126 // what you see below is the resulting simplification.
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
127
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
128 mediump float i_mix =
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
129 0.125 * raw[0] * sin(phase[0]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
130 0.25 * raw[1] * sin(phase[1]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
131 0.375 * raw[2] * sin(phase[2]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
132 0.5 * raw[3] * sin(phase[3]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
133 0.375 * raw[4] * sin(phase[4]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
134 0.25 * raw[5] * sin(phase[5]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
135 0.125 * raw[6] * sin(phase[6]);
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
136
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
137 mediump float q_mix =
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
138 0.125 * raw[0] * cos(phase[0]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
139 0.25 * raw[1] * cos(phase[1]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
140 0.375 * raw[2] * cos(phase[2]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
141 0.5 * raw[3] * cos(phase[3]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
142 0.375 * raw[4] * cos(phase[4]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
143 0.25 * raw[5] * cos(phase[5]) +
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
144 0.125 * raw[6] * cos(phase[6]);
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
145
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
146 // Convert YIQ back to RGB and output it
2343
49bd818ec9d8 Updated NTSC shader from Sik
Michael Pavone <pavone@retrodev.com>
parents: 2329
diff changeset
147 gl_FragColor = pow(yiq2rgba(vec3(y_mix, i_mix, q_mix)),
49bd818ec9d8 Updated NTSC shader from Sik
Michael Pavone <pavone@retrodev.com>
parents: 2329
diff changeset
148 vec4(gamma, gamma, gamma, 1.0));
2329
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
149
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
150 // If you're curious to see what the raw composite signal looks like,
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
151 // comment out the above and uncomment the line below instead
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
152 //gl_FragColor = vec4(raw[0], raw[0], raw[0], 1.0);
2410
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
153
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
154 // Basic scanlines effect. This is done by multiplying the color against a
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
155 // "half sine" wave so the center is brighter and a narrow outer area in
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
156 // each scanline is noticeable darker.
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
157 // The weird constant in the middle line is 1-sqrt(2)/4 and it's used to
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
158 // make sure that the average multiplied value across the whole screen is 1
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
159 // to preserve the original brightness.
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
160 if (scanlines != 0) {
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
161 mediump float mult = sin(y * texsize.y * 3.1415926);
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
162 mult = abs(mult) * 0.5 + 0.646446609;
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
163 gl_FragColor *= vec4(mult, mult, mult, 1.0);
f1574b22d5d9 Update Sik's NTSC shader
Michael Pavone <pavone@retrodev.com>
parents: 2343
diff changeset
164 }
2329
06d5e9b08bdb Add NTSC composite shader by Sik
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
165 }