Encode stroke in scene

This just adds the first step of polyline stroking, which is adding it
to the scene. Also just a bit of cleaning up of dimensions into one
header file.

Cargo.lock

@@ -93,8 +93,7 @@ dependencies = [
 [[package]]
 name = "kurbo"
 version = "0.5.11"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bf50e17a1697110c694d47c5b1a6b64faf5eb3ffe5a286df23fb8cd516e33be6"
+source = "git+https://github.com/linebender/kurbo?rev=7bd7e66bd137e757305d170a0f9f2b4f7beeb299#7bd7e66bd137e757305d170a0f9f2b4f7beeb299"
 dependencies = [
  "arrayvec",
 ]
@@ -128,6 +127,7 @@ dependencies = [
 name = "piet-gpu"
 version = "0.1.0"
 dependencies = [
+ "kurbo",
  "piet",
  "piet-gpu-hal",
  "piet-gpu-types",

Cargo.toml

@@ -6,3 +6,7 @@ members = [
     "piet-gpu-hal",
     "piet-gpu-types"
 ]
+
+# TODO: remove when the flatten feature is published
+[patch.crates-io]
+kurbo = { git = "https://github.com/linebender/kurbo", rev = "7bd7e66bd137e757305d170a0f9f2b4f7beeb299" }

piet-gpu/Cargo.toml

@@ -13,6 +13,7 @@ path = "../piet-gpu-hal"
 path = "../piet-gpu-types"
 
 [dependencies]
+kurbo = "0.5.11"
 piet = "0.0.12"
 png = "0.16.2"
 rand = "0.7.3"

piet-gpu/shader/build.ninja

@@ -9,8 +9,8 @@ rule glsl
 
 build image.spv: glsl image.comp | scene.h
 
-build kernel1.spv: glsl kernel1.comp | scene.h tilegroup.h
+build kernel1.spv: glsl kernel1.comp | scene.h tilegroup.h setup.h
 
-build kernel3.spv: glsl kernel3.comp | scene.h tilegroup.h ptcl.h
+build kernel3.spv: glsl kernel3.comp | scene.h tilegroup.h ptcl.h setup.h
 
-build kernel4.spv: glsl kernel4.comp | ptcl.h
+build kernel4.spv: glsl kernel4.comp | ptcl.h setup.h

piet-gpu/shader/kernel1.comp

@@ -28,13 +28,7 @@ layout(set = 0, binding = 1) buffer TilegroupBuf {
 #include "scene.h"
 #include "tilegroup.h"
 
-// TODO: compute this
-#define WIDTH_IN_TILEGROUPS 4
-
-#define TILEGROUP_WIDTH_PX 512
-#define TILEGROUP_HEIGHT_PX 16
-
-#define TILEGROUP_INITIAL_ALLOC 1024
+#include "setup.h"
 
 #define MAX_STACK 8
 

piet-gpu/shader/kernel3.comp

@@ -24,19 +24,7 @@ layout(set = 0, binding = 2) buffer PtclBuf {
 #include "tilegroup.h"
 #include "ptcl.h"
 
-// TODO: compute all these
-
-#define WIDTH_IN_TILEGROUPS 4
-#define WIDTH_IN_TILES 128
-#define TILEGROUP_WIDTH_TILES 32
-#define TILE_WIDTH_PX 16
-#define TILE_HEIGHT_PX 16
-
-// Must be the same as kernel1. Might be a good idea to move these particular
-// constants to their own .h file.
-#define TILEGROUP_INITIAL_ALLOC 1024
-
-#define PTCL_INITIAL_ALLOC 4096
+#include "setup.h"
 
 void main() {
     uint tile_ix = gl_GlobalInvocationID.y * WIDTH_IN_TILES + gl_GlobalInvocationID.x;

piet-gpu/shader/kernel4.comp

@@ -20,13 +20,7 @@ layout(set = 0, binding = 1) buffer ImageBuf {
 
 #include "ptcl.h"
 
-// TODO: make the image size dynamic.
-#define IMAGE_WIDTH 2048
-#define IMAGE_HEIGHT 1535
-
-#define WIDTH_IN_TILES 128
-
-#define PTCL_INITIAL_ALLOC 4096
+#include "setup.h"
 
 void main() {
     uint tile_ix = gl_WorkGroupID.y * WIDTH_IN_TILES + gl_WorkGroupID.x;

piet-gpu/shader/setup.h

@@ -0,0 +1,25 @@
+// Various constants for the sizes of groups and tiles.
+
+// Much of this will be made dynamic in various ways, but for now it's easiest
+// to hardcode and keep all in one place.
+
+// TODO: make the image size dynamic.
+#define IMAGE_WIDTH 2048
+#define IMAGE_HEIGHT 1536
+
+// TODO: compute this
+#define WIDTH_IN_TILEGROUPS 4
+
+#define TILEGROUP_WIDTH_PX 512
+#define TILEGROUP_HEIGHT_PX 16
+
+#define TILEGROUP_INITIAL_ALLOC 1024
+
+// TODO: compute all these
+
+#define WIDTH_IN_TILES 128
+#define TILEGROUP_WIDTH_TILES 32
+#define TILE_WIDTH_PX 16
+#define TILE_HEIGHT_PX 16
+
+#define PTCL_INITIAL_ALLOC 4096

piet-gpu/src/main.rs

@@ -4,13 +4,12 @@ use std::path::Path;
 
 use rand::{Rng, RngCore};
 
-use piet::{Color, RenderContext};
 use piet::kurbo::{Circle, Point};
+use piet::{Color, RenderContext};
 
 use piet_gpu_hal::vulkan::VkInstance;
 use piet_gpu_hal::{CmdBuf, Device, MemFlags};
 
-
 mod render_ctx;
 
 use render_ctx::PietGpuRenderContext;
@@ -27,8 +26,10 @@ fn render_scene(rc: &mut impl RenderContext) {
     let mut rng = rand::thread_rng();
     for _ in 0..N_CIRCLES {
         let color = Color::from_rgba32_u32(rng.next_u32());
-        let center = Point::new(rng.gen_range(0.0, WIDTH as f64),
-        rng.gen_range(0.0, HEIGHT as f64));
+        let center = Point::new(
+            rng.gen_range(0.0, WIDTH as f64),
+            rng.gen_range(0.0, HEIGHT as f64),
+        );
         let radius = rng.gen_range(0.0, 50.0);
         let circle = Circle::new(center, radius);
         rc.fill(circle, &color);

piet-gpu/src/render_ctx.rs

@@ -1,10 +1,10 @@
 use std::borrow::Cow;
 
-use piet_gpu_types::encoder::{Encode, Encoder};
+use piet_gpu_types::encoder::{Encode, Encoder, Ref};
 use piet_gpu_types::scene;
-use piet_gpu_types::scene::{Bbox, PietCircle, PietItem, SimpleGroup};
+use piet_gpu_types::scene::{Bbox, PietCircle, PietItem, PietStrokePolyLine, SimpleGroup};
 
-use piet::kurbo::{Affine, Point, Rect, Shape};
+use piet::kurbo::{Affine, PathEl, Point, Rect, Shape};
 
 use piet::{
     Color, Error, FixedGradient, Font, FontBuilder, HitTestPoint, HitTestTextPosition, ImageFormat,
@@ -39,6 +39,8 @@ pub enum PietGpuBrush {
     Gradient,
 }
 
+const TOLERANCE: f64 = 0.1;
+
 impl PietGpuRenderContext {
     pub fn new() -> PietGpuRenderContext {
         let mut encoder = Encoder::new();
@@ -104,7 +106,24 @@ impl RenderContext for PietGpuRenderContext {
 
     fn clear(&mut self, _color: Color) {}
 
-    fn stroke(&mut self, _shape: impl Shape, _brush: &impl IntoBrush<Self>, _width: f64) {}
+    fn stroke(&mut self, shape: impl Shape, brush: &impl IntoBrush<Self>, width: f64) {
+        let bbox = shape.bounding_box();
+        let brush = brush.make_brush(self, || bbox).into_owned();
+        let path = shape.to_bez_path(TOLERANCE);
+        let (n_points, points) = flatten_shape(&mut self.encoder, path);
+        match brush {
+            PietGpuBrush::Solid(rgba_color) => {
+                let poly_line = PietStrokePolyLine {
+                    rgba_color,
+                    width: width as f32,
+                    n_points,
+                    points,
+                };
+                self.push_item(PietItem::Poly(poly_line), bbox);
+            }
+            _ => (),
+        }
+    }
 
     fn stroke_styled(
         &mut self,
@@ -116,13 +135,7 @@ impl RenderContext for PietGpuRenderContext {
     }
 
     fn fill(&mut self, shape: impl Shape, brush: &impl IntoBrush<Self>) {
-        let dummy_closure = || Rect {
-            x0: 0.0,
-            x1: 0.0,
-            y0: 0.0,
-            y1: 0.0,
-        };
-        let brush = brush.make_brush(self, dummy_closure).into_owned();
+        let brush = brush.make_brush(self, || shape.bounding_box()).into_owned();
 
         match shape.as_circle() {
             Some(circle) => match brush {
@@ -212,6 +225,45 @@ impl RenderContext for PietGpuRenderContext {
     }
 }
 
+fn flatten_shape(
+    encoder: &mut Encoder,
+    path: impl Iterator<Item = PathEl>,
+) -> (u32, Ref<scene::Point>) {
+    let mut points = Vec::new();
+    let mut start_pt = None;
+    let mut last_pt = None;
+    kurbo::flatten(path, TOLERANCE, |el| {
+        match el {
+            PathEl::MoveTo(p) => {
+                let scene_pt = to_scene_point(p);
+                start_pt = Some(clone_scene_pt(&scene_pt));
+                if !points.is_empty() {
+                    points.push(scene::Point { xy: [std::f32::NAN, std::f32::NAN ]});
+                }
+                last_pt = Some(clone_scene_pt(&scene_pt));
+                points.push(scene_pt);
+            }
+            PathEl::LineTo(p) => {
+                let scene_pt = to_scene_point(p);
+                last_pt = Some(clone_scene_pt(&scene_pt));
+                points.push(scene_pt);
+            }
+            PathEl::ClosePath => {
+                if let (Some(start), Some(last)) = (start_pt.take(), last_pt.take()) {
+                    if start.xy != last.xy {
+                        points.push(start);
+                    }
+                }
+            }
+            _ => (),
+        }
+        println!("{:?}", el);
+    });
+    let n_points = points.len() as u32;
+    let points_ref = points.encode(encoder).transmute();
+    (n_points, points_ref)
+}
+
 impl Text for PietGpuText {
     type Font = PietGpuFont;
     type FontBuilder = PietGpuFontBuilder;
@@ -295,3 +347,10 @@ fn to_scene_point(point: Point) -> scene::Point {
         xy: [point.x as f32, point.y as f32],
     }
 }
+
+// TODO: allow #[derive(Clone)] in piet-gpu-derive.
+fn clone_scene_pt(p: &scene::Point) -> scene::Point {
+    scene::Point {
+        xy: p.xy
+    }
+}