Keep CC Simple Wire Removal between points A and B (#1724)

crates/effects/src/keying2.rs

@@ -363,7 +363,9 @@ fn wire_removal(ctx: &EffectCtx, mut b: Buf) -> Buf {
             let (qx, qy) = (x as f64 + 0.5 - ax, y as f64 + 0.5 - ay);
             let d = qx * nx + qy * ny;
             let ad = d.abs();
-            if ad > half + soft_w {
+            // The wire is the segment A to B, not an endless line.
+            let along = qx * tx + qy * ty;
+            if !(0.0..=len).contains(&along) || ad > half + soft_w {
                 continue;
             }
             // Positions just outside the wire on both sides.
@@ -580,6 +582,24 @@ mod tests {
         }
     }
 
+    #[test]
+    fn wire_removal_stays_between_a_and_b() {
+        let mut img = Image::filled(20, 20, [0.5, 0.5, 0.5, 1.0]);
+        for y in 0..20 {
+            img.set(10, y, [0.0, 0.0, 0.0, 1.0]);
+        }
+        let out = run_fx(
+            "ec.key.ccsimplewireremoval",
+            &[("pointA", Value::Vec2([10.5, 5.0])), ("pointB", Value::Vec2([10.5, 15.0])), ("removalStyle", Value::Enum(0)), ("thickness", num(3.0))],
+            img.clone(),
+            0.0,
+            EffectEnv::default(),
+        );
+        assert!((out.img.get(10, 10)[0] - 0.5).abs() < 0.05, "inside the segment");
+        assert_eq!(out.img.get(10, 2), img.get(10, 2), "before A");
+        assert_eq!(out.img.get(10, 18), img.get(10, 18), "after B");
+    }
+
     #[test]
     fn wire_removal_frame_offset_uses_neighbour_frame() {
         use crate::{EffectHost, LayerPixels};

crates/gpu/src/fx_pixel2.rs

@@ -493,7 +493,7 @@ fn wire_removal(e: &mut Enc, ctx: &EffectCtx, b: GBuf) -> Option<GBuf> {
     let mut p = Params::default();
     p.u[0][0] = ctx.params.e("removalStyle");
     p.f[0] = [a.0 as f32, a.1 as f32, -ty as f32, tx as f32];
-    p.f[1] = [half as f32, (half * slope as f64) as f32, mirror, 0.0];
+    p.f[1] = [half as f32, (half * slope as f64) as f32, mirror, len as f32];
     run(e, "fp2_wire", &p, b, None, None)
 }
 

crates/gpu/src/shaders/fx_pixel2.wgsl

@@ -828,7 +828,7 @@ fn fp2_io_final(@builtin(global_invocation_id) gid: vec3<u32>) {
 }
 
 // ---------------------------------------------------------------- CC Simple Wire Removal (keying2::wire_removal)
-// u[0].x = style; f[0] = (ax, ay, nx, ny); f[1] = (hw thickness, soft width, mirror).
+// u[0].x = style; f[0] = (ax, ay, nx, ny); f[1] = (hw thickness, soft width, mirror, segment length).
 
 fn fp2_wire_pos(base: vec2<f32>, nrm: vec2<f32>, s: f32) -> vec4<f32> {
     return sample_bilinear_clamped(src, base.x + nrm.x * s, base.y + nrm.y * s);
@@ -851,7 +851,9 @@ fn fp2_wire(@builtin(global_invocation_id) gid: vec3<u32>) {
     let q = vec2<f32>(fx - a.x, fy - a.y);
     let d = q.x * nrm.x + q.y * nrm.y;
     let ad = abs(d);
-    if (ad > hw + soft_w) {
+    // The wire is the segment A to B: the tangent is the normal turned back by 90 degrees.
+    let along = q.x * nrm.y - q.y * nrm.x;
+    if (along < 0.0 || along > P.f[1].w || ad > hw + soft_w) {
         textureStore(out, p, px);
         return;
     }