swaits
dacc631d57
Replace Chebyshev distance with a rounded box SDF for the cursor avoidance shape. Eliminates diagonal artifacts where the sharp corners of a pure square distance field intersected the ring geometry.
76 lines
2.4 KiB
WebGPU Shading Language
76 lines
2.4 KiB
WebGPU Shading Language
struct Uniforms {
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screen_size: vec2f,
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cursor_pos: vec2f,
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// Outer rounded rect: inset from screen edge
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outer_inset: f32,
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outer_corner_radius: f32,
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// Inner rounded rect: inset further by ring_width
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ring_width: f32,
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inner_corner_radius: f32,
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// Glow
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glow_spread: f32,
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// Cursor avoidance
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cursor_avoid_radius: f32,
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cursor_avoid_falloff: f32,
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// Color temperature (linear RGB)
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_pad: f32,
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color: vec3f,
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_pad2: f32,
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}
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@group(0) @binding(0) var<uniform> u: Uniforms;
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@vertex
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fn vs_main(@builtin(vertex_index) i: u32) -> @builtin(position) vec4f {
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let x = f32(i32(i) / 2) * 4.0 - 1.0;
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let y = f32(i32(i) % 2) * 4.0 - 1.0;
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return vec4f(x, y, 0.0, 1.0);
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}
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// Rounded rectangle SDF (Inigo Quilez).
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fn rounded_rect_sdf(p: vec2f, h: vec2f, r: f32) -> f32 {
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let q = abs(p) - h + vec2f(r);
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return length(max(q, vec2f(0.0))) + min(max(q.x, q.y), 0.0) - r;
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}
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@fragment
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fn fs_main(@builtin(position) pos: vec4f) -> @location(0) vec4f {
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let center = u.screen_size / 2.0;
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let p = pos.xy - center;
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// Outer rounded rect
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let outer_half = center - vec2f(u.outer_inset);
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let sd_outer = rounded_rect_sdf(p, outer_half, u.outer_corner_radius);
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// Inner rounded rect
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let inner_half = outer_half - vec2f(u.ring_width);
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let sd_inner = rounded_rect_sdf(p, inner_half, u.inner_corner_radius);
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// Ring: inside outer AND outside inner = solid at full brightness
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var alpha: f32;
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if sd_outer <= 0.0 && sd_inner >= 0.0 {
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alpha = 1.0;
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} else if sd_outer > 0.0 {
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// Gaussian glow fading outward
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let t = sd_outer / u.glow_spread;
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alpha = exp(-3.0 * t * t);
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} else {
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// Gaussian glow fading inward
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let t = -sd_inner / u.glow_spread;
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alpha = exp(-3.0 * t * t);
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}
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// Cursor avoidance — rounded square (box SDF with corner rounding)
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let cursor_half = vec2f(u.cursor_avoid_radius);
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let cursor_corner = u.cursor_avoid_radius * 0.3; // 30% rounding smooths the diagonals
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let cursor_sd = rounded_rect_sdf(pos.xy - u.cursor_pos, cursor_half, cursor_corner);
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if cursor_sd < u.cursor_avoid_falloff {
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let t_avoid = clamp(cursor_sd / u.cursor_avoid_falloff, 0.0, 1.0);
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alpha *= t_avoid * t_avoid * (3.0 - 2.0 * t_avoid);
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}
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// Premultiplied color output
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let rgb = u.color * alpha;
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return vec4f(rgb, alpha);
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}
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