Merge main into M12.7 (environment background layers keep their 3D runs on the CPU path)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/gpu/src/ops.rs

@@ -155,11 +155,13 @@ pub fn quantize(e: &mut Enc, img: &GpuImage, levels: f32) -> GpuImage {
 }
 
 fn curve_id(s: Option<effectcraft_color::ColorSpace>) -> u32 {
-    use effectcraft_color::ColorSpace::*;
-    match s {
-        None => 0,
-        Some(Srgb | DisplayP3) => 1,
-        Some(Rec709 | Rec2020) => 2,
+    use effectcraft_color::space::Curve;
+    match s.map(|s| s.curve()) {
+        None | Some(Curve::Linear) => 0,
+        Some(Curve::Srgb) => 1,
+        Some(Curve::Gamma24) => 2,
+        Some(Curve::Pq) => 3,
+        Some(Curve::Hlg) => 4,
     }
 }
 

crates/gpu/src/shaders/common.wgsl

@@ -428,7 +428,44 @@ fn hsl_to_rgb(h: f32, s: f32, l: f32) -> vec3<f32> {
     return vec3<f32>(hsl_channel(h + 1.0 / 3.0, p, q), hsl_channel(h, p, q), hsl_channel(h - 1.0 / 3.0, p, q));
 }
 
-// ColorSpace transfer curves: 1 = sRGB (sRGB, Display P3), 2 = 2.4 power (Rec. 709 / 2020).
+// ColorSpace transfer curves: 1 = sRGB (sRGB, Display P3), 2 = 2.4 power (Rec. 709 / 2020),
+// 3 = SMPTE ST 2084 PQ and 4 = BT.2100 HLG (linear 1.0 = the BT.2408 reference white).
+const PQ_M1: f32 = 0.1593017578125;
+const PQ_M2: f32 = 78.84375;
+const PQ_C1: f32 = 0.8359375;
+const PQ_C2: f32 = 18.8515625;
+const PQ_C3: f32 = 18.6875;
+const PQ_WHITE: f32 = 0.0203;
+const HLG_A: f32 = 0.17883277;
+const HLG_B: f32 = 0.28466892;
+const HLG_C: f32 = 0.55991073;
+const HLG_REF: f32 = 0.26496256;
+
+fn pq_decode(e: f32) -> f32 {
+    let p = pow(clamp(e, 0.0, 1.0), 1.0 / PQ_M2);
+    return pow(max(p - PQ_C1, 0.0) / (PQ_C2 - PQ_C3 * p), 1.0 / PQ_M1) / PQ_WHITE;
+}
+
+fn pq_encode(l: f32) -> f32 {
+    let y = pow(max(l * PQ_WHITE, 0.0), PQ_M1);
+    return pow((PQ_C1 + PQ_C2 * y) / (1.0 + PQ_C3 * y), PQ_M2);
+}
+
+fn hlg_decode(v: f32) -> f32 {
+    if (v <= 0.5) {
+        return v * v / 3.0 / HLG_REF;
+    }
+    return (exp((v - HLG_C) / HLG_A) + HLG_B) / 12.0 / HLG_REF;
+}
+
+fn hlg_encode(l: f32) -> f32 {
+    let e = max(l * HLG_REF, 0.0);
+    if (e <= 1.0 / 12.0) {
+        return sqrt(3.0 * e);
+    }
+    return HLG_A * log(12.0 * e - HLG_B) + HLG_C;
+}
+
 fn curve_decode(curve: u32, v: f32) -> f32 {
     let a = abs(v);
     var l = a;
@@ -436,6 +473,10 @@ fn curve_decode(curve: u32, v: f32) -> f32 {
         l = srgb_to_linear(a);
     } else if (curve == 2u) {
         l = powz(a, 2.4);
+    } else if (curve == 3u) {
+        l = pq_decode(a);
+    } else if (curve == 4u) {
+        l = hlg_decode(a);
     }
     return select(l, -l, v < 0.0);
 }
@@ -447,6 +488,10 @@ fn curve_encode(curve: u32, v: f32) -> f32 {
         e = linear_to_srgb(a);
     } else if (curve == 2u) {
         e = powz(a, 1.0 / 2.4);
+    } else if (curve == 3u) {
+        e = pq_encode(a);
+    } else if (curve == 4u) {
+        e = hlg_encode(a);
     }
     return select(e, -e, v < 0.0);
 }

crates/gpu/src/walk.rs

@@ -49,6 +49,14 @@ pub(crate) fn render<'g>(e: &mut Enc<'g>, r: &Renderer, comp_id: ItemId, t: Tick
             canvas = ops::quantize(e, &canvas, l);
         }
     }
+    if r.depth() == 0
+        && let Some((lin, mode, enc)) = pipe.output_hdr()
+    {
+        on_cpu(e, &mut canvas, |img| {
+            effectcraft_render::color::output_hdr(img, lin, mode, enc);
+            pipe.quantize(img);
+        })?;
+    }
     Some(canvas)
 }