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-rw-r--r--shaders/prebuilt/post-glitch.frag.glsl138
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diff --git a/shaders/prebuilt/post-glitch.frag.glsl b/shaders/prebuilt/post-glitch.frag.glsl
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--- a/shaders/prebuilt/post-glitch.frag.glsl
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-#version 450
-// pardes's Shadertoy prefix (docs/render-pipeline.md ยง6), put before every
-// post pass: a bundled one in shaders/post/ at build time, a user's file at
-// run time. The uniform names, types and std140 order are ghostty 1.3.2's
-// (src/renderer/shaders/shadertoy_prefix.glsl), so a shader written for
-// ghostty runs here; only the bindings are SDL GPU's (a fragment shader's
-// textures in set 2, its uniform blocks in set 3). Y is down everywhere, as
-// on ghostty's Metal renderer: fragCoord, iChannel0's uv and the cursor
-// rectangles share one top-left space, and iCurrentCursor is (left x,
-// BOTTOM-edge y, width, height) in framebuffer pixels.
-
-layout(set = 3, binding = 0, std140) uniform Globals {
- uniform vec3 iResolution;
- uniform float iTime;
- uniform float iTimeDelta;
- uniform float iFrameRate;
- uniform int iFrame;
- uniform float iChannelTime[4];
- uniform vec3 iChannelResolution[4];
- uniform vec4 iMouse;
- uniform vec4 iDate;
- uniform float iSampleRate;
- uniform vec4 iCurrentCursor;
- uniform vec4 iPreviousCursor;
- uniform vec4 iCurrentCursorColor;
- uniform vec4 iPreviousCursorColor;
- uniform int iCurrentCursorStyle;
- uniform int iPreviousCursorStyle;
- uniform int iCursorVisible;
- uniform float iTimeCursorChange;
- uniform float iTimeFocus;
- uniform int iFocus;
- uniform vec3 iPalette[256];
- uniform vec3 iBackgroundColor;
- uniform vec3 iForegroundColor;
- uniform vec3 iCursorColor;
- uniform vec3 iCursorText;
- uniform vec3 iSelectionForegroundColor;
- uniform vec3 iSelectionBackgroundColor;
-};
-
-// pardes's own: pardesOpaque is 1 when the window is opaque, so a pass
-// cannot punch holes in it through its alpha; pardesLevel is a bundled
-// pass's strength, 1 to 3 (`Crt 3`), and 0 for a user's file.
-layout(set = 3, binding = 1, std140) uniform PardesPost {
- float pardesOpaque;
- float pardesLevel;
-};
-
-// A bundled pass's constant at levels 1, 2 and 3.
-float pardesByLevel(float one, float two, float three) {
- return pardesLevel < 1.5 ? one : (pardesLevel < 2.5 ? two : three);
-}
-
-#define CURSORSTYLE_BLOCK 0
-#define CURSORSTYLE_BLOCK_HOLLOW 1
-#define CURSORSTYLE_BAR 2
-#define CURSORSTYLE_UNDERLINE 3
-#define CURSORSTYLE_LOCK 4
-
-layout(set = 2, binding = 0) uniform sampler2D iChannel0;
-
-layout(location = 0) out vec4 _fragColor;
-
-#define texture2D texture
-
-void mainImage(out vec4 fragColor, in vec2 fragCoord);
-void main() {
- mainImage(_fragColor, gl_FragCoord.xy);
- if (pardesOpaque > 0.5) _fragColor.a = 1.0;
-}
-
-// The shader's own lines count from 1, so glslc's errors name them.
-#line 1
-// Glitch: now and then the signal slips. At the default level, every couple
-// of seconds a short
-// burst tears a few horizontal bands sideways and pulls their red and blue
-// apart; the bands are sized in pixels and the burst eases in and out over
-// a fraction of a second, so it reads as one event rather than a flicker,
-// and it looks the same at 60 or 144 Hz because every step is keyed to
-// iTime, not to frames. Between bursts the page is left exactly as it is.
-// A torn band's brightness dips in linear light. It is a Shadertoy file:
-// pardes puts its prefix before it.
-
-// Each at levels 1, 2 and 3 (`Glitch 1`..`Glitch 3`); 2 is the default. A
-// higher level slips more often and harder.
-float period() { return pardesByLevel(4.5, 2.4, 0.55); } // seconds between bursts, on average
-float burst() { return pardesByLevel(0.2, 0.28, 0.5); } // seconds a burst lasts
-float stepHz() { return pardesByLevel(20.0, 24.0, 30.0); } // how often a burst re-tears
-float shiftPx() { return pardesByLevel(8.0, 14.0, 34.0); }
-float splitPx() { return pardesByLevel(1.5, 2.5, 6.0); }
-float dip() { return pardesByLevel(0.08, 0.12, 0.22); }
-float tearFrom() { return pardesByLevel(0.8, 0.72, 0.35); } // how few bands tear
-
-float hash(vec2 p) {
- vec3 q = fract(vec3(p.xyx) * 0.1031);
- q += dot(q, q.yzx + 33.33);
- return fract((q.x + q.y) * q.z);
-}
-
-vec3 toLinear(vec3 c) {
- return mix(pow((c + 0.055) / 1.055, vec3(2.4)), c / 12.92, lessThanEqual(c, vec3(0.04045)));
-}
-
-vec3 toSrgb(vec3 c) {
- c = max(c, vec3(0.0));
- return mix(1.055 * pow(c, vec3(1.0 / 2.4)) - 0.055, c * 12.92, lessThanEqual(c, vec3(0.0031308)));
-}
-
-void mainImage(out vec4 fragColor, in vec2 fragCoord) {
- vec2 size = iResolution.xy;
- vec2 uv = fragCoord / size;
- // Which burst window this is, when in it the burst starts, and how far
- // into the burst we are: 0 outside one.
- float window = floor(iTime / period());
- float start = window * period() + hash(vec2(window, 7.0)) * (period() - burst());
- float t = (iTime - start) / burst();
- float live = step(0.0, t) * step(t, 1.0);
- float envelope = live * sin(3.14159265 * clamp(t, 0.0, 1.0));
- if (envelope <= 0.0) {
- fragColor = texture(iChannel0, uv);
- return;
- }
- // Bands of 6 to 40 px, re-cut at stepHz() during the burst; about one
- // band in four tears.
- float tick = floor(iTime * stepHz());
- float band_px = mix(6.0, 40.0, hash(vec2(tick, 3.0)));
- float band = floor(fragCoord.y / band_px);
- float roll = hash(vec2(band, tick));
- float tear = smoothstep(tearFrom(), tearFrom() + 0.18, roll) * envelope;
- float shift = (hash(vec2(tick, band + 11.0)) - 0.5) * 2.0 * shiftPx() * tear;
- vec2 at = vec2(fragCoord.x + shift, fragCoord.y);
- vec2 split = vec2(splitPx() * tear, 0.0);
- vec4 center = texture(iChannel0, at / size);
- vec3 col = vec3(texture(iChannel0, (at + split) / size).r, center.g, texture(iChannel0, (at - split) / size).b);
- col = toSrgb(toLinear(col) * (1.0 - dip() * tear));
- fragColor = vec4(col, center.a);
-}