Fix pathtag limit, add unlicense

Adds Unlicense to the SPDX line, and also relaxes the 64k (or any) limit on the number of pathtags in the CPU case.

The CPU shaders don't exactly match the GPU in the "use_large_path_scan" case, but they do work.

crates/encoding/src/path.rs

@@ -227,9 +227,10 @@ pub struct Path {
 pub struct Tile {
     /// Accumulated backdrop at the left edge of the tile.
     pub backdrop: i32,
-    /// An enum that can hold either a count or an index to the
-    /// beginning of an allocated slice. In the latter case, the
-    /// bits are inverted.
+    /// An enum that holds either the count of the number of path
+    /// segments in this tile, or an index to the beginning of an
+    /// allocated slice of `PathSegment` objects. In the latter case,
+    /// the bits are inverted.
     pub segment_count_or_ix: u32,
 }
 

src/cpu_shader/backdrop.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{ConfigUniform, Path, Tile};
 

src/cpu_shader/bbox_clear.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{ConfigUniform, PathBbox};
 

src/cpu_shader/binning.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{BinHeader, BumpAllocators, ConfigUniform, DrawMonoid, PathBbox};
 

src/cpu_shader/clip_leaf.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{Clip, ConfigUniform, DrawMonoid, PathBbox};
 

src/cpu_shader/clip_reduce.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{Clip, ClipBic, ClipElement, PathBbox};
 

src/cpu_shader/coarse.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{BinHeader, BumpAllocators, ConfigUniform, DrawMonoid, DrawTag, Path, Tile};
 

src/cpu_shader/draw_leaf.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{Clip, ConfigUniform, DrawMonoid, DrawTag, Monoid, PathBbox};
 

src/cpu_shader/draw_reduce.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{ConfigUniform, DrawMonoid, DrawTag, Monoid};
 

src/cpu_shader/fine.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{ConfigUniform, PathSegment, Tile};
 

src/cpu_shader/flatten.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use crate::cpu_dispatch::CpuBinding;
 

src/cpu_shader/mod.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 //! CPU implementations of shader stages.
 

src/cpu_shader/path_count.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{BumpAllocators, LineSoup, Path, SegmentCount, Tile};
 

src/cpu_shader/path_count_setup.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{BumpAllocators, IndirectCount};
 

src/cpu_shader/path_tiling.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{BumpAllocators, LineSoup, Path, PathSegment, SegmentCount, Tile};
 

src/cpu_shader/path_tiling_setup.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{BumpAllocators, IndirectCount};
 

src/cpu_shader/pathtag_reduce.rs

@@ -1,5 +1,5 @@
 // Copyright 2023 The Vello authors
-// SPDX-License-Identifier: Apache-2.0 OR MIT
+// SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
 use vello_encoding::{ConfigUniform, Monoid, PathMonoid};
 

src/render.rs

@@ -139,7 +139,8 @@ impl Render {
         );
         let mut pathtag_parent = reduced_buf;
         let mut large_pathtag_bufs = None;
-        if wg_counts.use_large_path_scan {
+        let use_large_path_scan = wg_counts.use_large_path_scan && !shaders.pathtag_is_cpu;
+        if use_large_path_scan {
             let reduced2_buf = ResourceProxy::new_buf(
                 buffer_sizes.path_reduced2.size_in_bytes().into(),
                 "reduced2_buf",
@@ -166,7 +167,7 @@ impl Render {
             buffer_sizes.path_monoids.size_in_bytes().into(),
             "tagmonoid_buf",
         );
-        let pathtag_scan = if wg_counts.use_large_path_scan {
+        let pathtag_scan = if use_large_path_scan {
             shaders.pathtag_scan_large
         } else {
             shaders.pathtag_scan

src/shaders.rs

@@ -79,6 +79,9 @@ pub struct FullShaders {
     pub path_tiling_setup: ShaderId,
     pub path_tiling: ShaderId,
     pub fine: ShaderId,
+    // 2-level dispatch works for CPU pathtag scan even for large
+    // inputs, 3-level is not yet implemented.
+    pub pathtag_is_cpu: bool,
 }
 
 #[cfg(feature = "wgpu")]
@@ -324,6 +327,7 @@ pub fn full_shaders(device: &Device, engine: &mut WgpuEngine) -> Result<FullShad
         path_tiling_setup,
         path_tiling,
         fine,
+        pathtag_is_cpu: false,
     })
 }
 
@@ -355,6 +359,7 @@ impl FullShaders {
         engine.set_cpu_shader(self.coarse, cpu_shader::coarse);
         engine.set_cpu_shader(self.path_tiling_setup, cpu_shader::path_tiling_setup);
         engine.set_cpu_shader(self.path_tiling, cpu_shader::path_tiling);
+        self.pathtag_is_cpu = true;
     }
 }