diff options
Diffstat (limited to 'shaders/post')
| -rw-r--r-- | shaders/post/crt.glsl | 83 | ||||
| -rw-r--r-- | shaders/post/prefix.glsl | 74 |
2 files changed, 157 insertions, 0 deletions
diff --git a/shaders/post/crt.glsl b/shaders/post/crt.glsl new file mode 100644 index 00000000..768157ef --- /dev/null +++ b/shaders/post/crt.glsl @@ -0,0 +1,83 @@ +// Crt: a slot-mask tube's light, with nothing that moves a pixel. There is +// no barrel: every click lands where it is drawn, rails and grips at the +// window's edges included. What is left is light: a beam profile for the +// scanlines, an aperture mask, a soft bloom of the brightest ink, a faint +// vignette and the hum of a live tube. Everything is worked out in linear +// light and dithered back into 8 bits, so the vignette never bands. It is a +// Shadertoy file: pardes puts its prefix before it (shaders/post/prefix.glsl). + +const float TAU = 6.28318530718; +// Level 3 glows wider and from dimmer ink. +float bloomRadiusPx() { return pardesByLevel(1.75, 1.75, 3.0); } +float bloomThreshold() { return pardesByLevel(0.6, 0.6, 0.3); } // linear-light channel peak +const float BLOOM_SOFTNESS = 0.25; +const float SCAN_PERIOD_PX = 3.0; +const float MASK_PERIOD_PX = 3.0; +const float HUM_HZ = 0.11; + +// Each strength at levels 1, 2 and 3 (`Crt 1`..`Crt 3`): 2 is the default, +// 3 as strong as the old barrel CRT looked. +float chromaPx() { return pardesByLevel(0.2, 0.35, 2.2); } // red and blue apart, at the corners +float bloomStrength() { return pardesByLevel(0.03, 0.05, 0.3); } +float scanStrength() { return pardesByLevel(0.035, 0.07, 0.42); } +float maskStrength() { return pardesByLevel(0.01, 0.018, 0.12); } +float vignetteStrength() { return pardesByLevel(0.06, 0.12, 0.42); } // at the far corners only +float humStrength() { return pardesByLevel(0.002, 0.004, 0.012); } +float exposure() { return pardesByLevel(1.008, 1.015, 1.1); } + +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))); +} + +vec3 scene(vec2 uv) { + return toLinear(texture(iChannel0, uv).rgb); +} + +vec3 brightPass(vec2 uv) { + vec3 c = scene(uv); + float peak = max(c.r, max(c.g, c.b)); + return c * smoothstep(bloomThreshold(), bloomThreshold() + BLOOM_SOFTNESS, peak); +} + +// Interleaved gradient noise: a dither with no visible pattern. +float ign(vec2 p) { + return fract(52.9829189 * fract(dot(p, vec2(0.06711056, 0.00583715)))); +} + +void mainImage(out vec4 fragColor, in vec2 fragCoord) { + vec2 size = iResolution.xy; + vec2 texel = 1.0 / size; + vec2 uv = fragCoord / size; + vec2 cc = uv * 2.0 - 1.0; + float r2 = dot(cc, cc); + + // The beam converges least at the corners: red and blue drift apart + // there, by a third of a pixel. + vec2 chroma = cc * (chromaPx() * r2 * 0.5) * texel; + vec3 col = vec3(scene(uv + chroma).r, scene(uv).g, scene(uv - chroma).b); + + vec2 b = texel * bloomRadiusPx(); + vec3 bloom = brightPass(uv + vec2(b.x, 0.0)) + brightPass(uv - vec2(b.x, 0.0)) + + brightPass(uv + vec2(0.0, b.y)) + brightPass(uv - vec2(0.0, b.y)); + col += bloom * (0.25 * bloomStrength()); + + // A beam is brightest on its line and falls off between lines; the + // mask is three phosphor stripes a triad. Both average to one, so the + // theme keeps its brightness. + float line = 0.5 + 0.5 * cos(fragCoord.y * TAU / SCAN_PERIOD_PX); + col *= 1.0 - scanStrength() * (line * line - 0.375) / 0.625; + col *= 1.0 + maskStrength() * cos(fragCoord.x * TAU / MASK_PERIOD_PX + vec3(0.0, TAU / 3.0, 2.0 * TAU / 3.0)); + + float vignette = 1.0 - vignetteStrength() * pow(clamp(r2 * 0.5, 0.0, 1.0), 1.6); + float hum = 1.0 + humStrength() * sin((uv.y * 1.35 - iTime * HUM_HZ) * TAU); + col *= vignette * hum * exposure(); + + vec3 srgb = toSrgb(col); + srgb += (ign(fragCoord + float(iFrame % 64) * vec2(5.588238, 5.588238)) - 0.5) / 255.0; + fragColor = vec4(clamp(srgb, 0.0, 1.0), texture(iChannel0, uv).a); +} diff --git a/shaders/post/prefix.glsl b/shaders/post/prefix.glsl new file mode 100644 index 00000000..e718a98f --- /dev/null +++ b/shaders/post/prefix.glsl @@ -0,0 +1,74 @@ +#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 |