diff options
Diffstat (limited to 'ghostty/shaders/cursor_tail.glsl')
| -rw-r--r-- | ghostty/shaders/cursor_tail.glsl | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/ghostty/shaders/cursor_tail.glsl b/ghostty/shaders/cursor_tail.glsl new file mode 100644 index 0000000..0937138 --- /dev/null +++ b/ghostty/shaders/cursor_tail.glsl @@ -0,0 +1,234 @@ +// -- CONFIGURATION -- +vec4 TRAIL_COLOR = iCurrentCursorColor; // can change to eg: vec4(0.2, 0.6, 1.0, 0.5); +const float DURATION = 0.09; // in seconds +const float MAX_TRAIL_LENGTH = 0.2; +const float THRESHOLD_MIN_DISTANCE = 1.5; // min distance to show trail (units of cursor width) +const float BLUR = 2.0; // blur size in pixels (for antialiasing) + +// --- CONSTANTS for easing functions --- +const float PI = 3.14159265359; +const float C1_BACK = 1.70158; +const float C2_BACK = C1_BACK * 1.525; +const float C3_BACK = C1_BACK + 1.0; +const float C4_ELASTIC = (2.0 * PI) / 3.0; +const float C5_ELASTIC = (2.0 * PI) / 4.5; +const float SPRING_STIFFNESS = 9.0; +const float SPRING_DAMPING = 0.9; + +// --- EASING FUNCTIONS --- + +// // Linear +// float ease(float x) { +// return x; +// } + +// // EaseOutQuad +// float ease(float x) { +// return 1.0 - (1.0 - x) * (1.0 - x); +// } + +// // EaseOutCubic +// float ease(float x) { +// return 1.0 - pow(1.0 - x, 3.0); +// } + + +// // EaseOutQuart +// float ease(float x) { +// return 1.0 - pow(1.0 - x, 4.0); +// } + +// // EaseOutQuint +// float ease(float x) { +// return 1.0 - pow(1.0 - x, 5.0); +// } + +// // EaseOutSine +// float ease(float x) { +// return sin((x * PI) / 2.0); +// } + +// // EaseOutExpo +// float ease(float x) { +// return x == 1.0 ? 1.0 : 1.0 - pow(2.0, -10.0 * x); +// } + +// EaseOutCirc +float ease(float x) { + return sqrt(1.0 - pow(x - 1.0, 2.0)); +} + +// // EaseOutBack +// float ease(float x) { +// return 1.0 + C3_BACK * pow(x - 1.0, 3.0) + C1_BACK * pow(x - 1.0, 2.0); +// } + +// // EaseOutElastic +// float ease(float x) { +// return x == 0.0 ? 0.0 +// : x == 1.0 ? 1.0 +// : pow(2.0, -10.0 * x) * sin((x * 10.0 - 0.75) * C4_ELASTIC) + 1.0; +// } + +// Parametric Spring +// float ease(float x) { +// x = clamp(x, 0.0, 1.0); +// float decay = exp(-SPRING_DAMPING * SPRING_STIFFNESS * x); +// float freq = sqrt(SPRING_STIFFNESS * (1.0 - SPRING_DAMPING * SPRING_DAMPING)); +// float osc = cos(freq * 6.283185 * x) + (SPRING_DAMPING * sqrt(SPRING_STIFFNESS) / freq) * sin(freq * 6.283185 * x); +// return 1.0 - decay * osc; +// } + +float getSdfRectangle(in vec2 p, in vec2 xy, in vec2 b) +{ + vec2 d = abs(p - xy) - b; + return length(max(d, 0.0)) + min(max(d.x, d.y), 0.0); +} + +// Based on Inigo Quilez's 2D distance functions article: https://iquilezles.org/articles/distfunctions2d/ +// Potencially optimized by eliminating conditionals and loops to enhance performance and reduce branching + +float seg(in vec2 p, in vec2 a, in vec2 b, inout float s, float d) { + vec2 e = b - a; + vec2 w = p - a; + vec2 proj = a + e * clamp(dot(w, e) / dot(e, e), 0.0, 1.0); + float segd = dot(p - proj, p - proj); + d = min(d, segd); + + float c0 = step(0.0, p.y - a.y); + float c1 = 1.0 - step(0.0, p.y - b.y); + float c2 = 1.0 - step(0.0, e.x * w.y - e.y * w.x); + float allCond = c0 * c1 * c2; + float noneCond = (1.0 - c0) * (1.0 - c1) * (1.0 - c2); + float flip = mix(1.0, -1.0, step(0.5, allCond + noneCond)); + s *= flip; + return d; +} + +float getSdfParallelogram(in vec2 p, in vec2 v0, in vec2 v1, in vec2 v2, in vec2 v3) { + float s = 1.0; + float d = dot(p - v0, p - v0); + + d = seg(p, v0, v3, s, d); + d = seg(p, v1, v0, s, d); + d = seg(p, v2, v1, s, d); + d = seg(p, v3, v2, s, d); + + return s * sqrt(d); +} + +vec2 normalize(vec2 value, float isPosition) { + return (value * 2.0 - (iResolution.xy * isPosition)) / iResolution.y; +} + +float antialising(float distance) { + return 1. - smoothstep(0., normalize(vec2(BLUR, BLUR), 0.).x, distance); +} + +float determineIfTopRightIsLeading(vec2 a, vec2 b) { + float condition1 = step(b.x, a.x) * step(a.y, b.y); // a.x < b.x && a.y > b.y + float condition2 = step(a.x, b.x) * step(b.y, a.y); // a.x > b.x && a.y < b.y + + // if neither condition is met, return 1 (else case) + return 1.0 - max(condition1, condition2); +} + +vec2 getRectangleCenter(vec4 rectangle) { + return vec2(rectangle.x + (rectangle.z / 2.), rectangle.y - (rectangle.w / 2.)); +} + + +void mainImage(out vec4 fragColor, in vec2 fragCoord){ + #if !defined(WEB) + fragColor = texture(iChannel0, fragCoord.xy / iResolution.xy); + #endif + + // normalization & setup(-1, 1 coords) + vec2 vu = normalize(fragCoord, 1.); + vec2 offsetFactor = vec2(-.5, 0.5); + + vec4 currentCursor = vec4(normalize(iCurrentCursor.xy, 1.), normalize(iCurrentCursor.zw, 0.)); + vec4 previousCursor = vec4(normalize(iPreviousCursor.xy, 1.), normalize(iPreviousCursor.zw, 0.)); + + vec2 centerCC = currentCursor.xy - (currentCursor.zw * offsetFactor); + vec2 centerCP = previousCursor.xy - (previousCursor.zw * offsetFactor); + + vec2 delta = centerCP - centerCC; + float lineLength = length(delta); + + float sdfCurrentCursor = getSdfRectangle(vu, centerCC, currentCursor.zw * 0.5); + + vec4 newColor = vec4(fragColor); + + float minDist = currentCursor.w * THRESHOLD_MIN_DISTANCE; + float progress = clamp((iTime - iTimeCursorChange) / DURATION, 0.0, 1.0); + if (lineLength > minDist) { + // ANIMATION logic + + float head_eased = 0.0; + float tail_eased = 0.0; + + float tail_delay_factor = MAX_TRAIL_LENGTH / lineLength; + + float isLongMove = step(MAX_TRAIL_LENGTH, lineLength); + + float head_eased_short = ease(progress); + float tail_eased_short = ease(smoothstep(tail_delay_factor, 1.0, progress)); + float head_eased_long = 1.0; + float tail_eased_long = ease(progress); + + head_eased = mix(head_eased_long, head_eased_short, isLongMove); + tail_eased = mix(tail_eased_long, tail_eased_short, isLongMove); + + // detect straight moves + vec2 delta_abs = abs(centerCC - centerCP); + float threshold = 0.001; + float isHorizontal = step(delta_abs.y, threshold); + float isVertical = step(delta_abs.x, threshold); + float isStraightMove = max(isHorizontal, isVertical); + + // -- Making the parallelogram sdf (diagonal move) -- + + // animate the TOP-LEFT corners + vec2 head_pos_tl = mix(previousCursor.xy, currentCursor.xy, head_eased); + vec2 tail_pos_tl = mix(previousCursor.xy, currentCursor.xy, tail_eased); + + float isTopRightLeading = determineIfTopRightIsLeading(currentCursor.xy, previousCursor.xy); + float isBottomLeftLeading = 1.0 - isTopRightLeading; + + // v0, v1 : "front" of the trail (head) + vec2 v0 = vec2(head_pos_tl.x + currentCursor.z * isTopRightLeading, head_pos_tl.y - currentCursor.w); + vec2 v1 = vec2(head_pos_tl.x + currentCursor.z * isBottomLeftLeading, head_pos_tl.y); + + // v2, v3: "back" of the trail (tail) + vec2 v2 = vec2(tail_pos_tl.x + currentCursor.z * isBottomLeftLeading, tail_pos_tl.y); + vec2 v3 = vec2(tail_pos_tl.x + currentCursor.z * isTopRightLeading, tail_pos_tl.y - previousCursor.w); + + float sdfTrail_diag = getSdfParallelogram(vu, v0, v1, v2, v3); + + // -- Making the rectangle sdf (straight move) -- + + vec2 head_center = mix(centerCP, centerCC, head_eased); + vec2 tail_center = mix(centerCP, centerCC, tail_eased); + + vec2 min_center = min(head_center, tail_center); + vec2 max_center = max(head_center, tail_center); + + vec2 box_size = (max_center - min_center) + currentCursor.zw; + vec2 box_center = (min_center + max_center) * 0.5; + + float sdfTrail_rect = getSdfRectangle(vu, box_center, box_size * 0.5); + + // -- FINAL SELECTING AND DRAWING -- + float sdfTrail = mix(sdfTrail_diag, sdfTrail_rect, isStraightMove); + + vec4 trail = TRAIL_COLOR; + float trailAlpha = antialising(sdfTrail); + newColor = mix(newColor, trail, trailAlpha); + + // punch hole + newColor = mix(newColor, fragColor, step(sdfCurrentCursor, 0.)); + } + + fragColor = newColor; +} |