Add stroke modes (#84)

Author: tychedelia

Cargo.lock

@@ -89,6 +89,14 @@ path = "examples/midi.rs"
 name = "gltf_load"
 path = "examples/gltf_load.rs"
 
+[[example]]
+name = "stroke_2d"
+path = "examples/stroke_2d.rs"
+
+[[example]]
+name = "stroke_3d"
+path = "examples/stroke_3d.rs"
+
 [[example]]
 name = "custom_material"
 path = "examples/custom_material.rs"

Cargo.toml

@@ -281,6 +281,32 @@ pub extern "C" fn processing_set_stroke_weight(graphics_id: u64, weight: f32) {
     error::check(|| graphics_record_command(graphics_entity, DrawCommand::StrokeWeight(weight)));
 }
 
+/// Set the stroke cap mode.
+#[unsafe(no_mangle)]
+pub extern "C" fn processing_set_stroke_cap(graphics_id: u64, cap: u8) {
+    error::clear_error();
+    let graphics_entity = Entity::from_bits(graphics_id);
+    error::check(|| {
+        graphics_record_command(
+            graphics_entity,
+            DrawCommand::StrokeCap(processing::prelude::StrokeCapMode::from(cap)),
+        )
+    });
+}
+
+/// Set the stroke join mode.
+#[unsafe(no_mangle)]
+pub extern "C" fn processing_set_stroke_join(graphics_id: u64, join: u8) {
+    error::clear_error();
+    let graphics_entity = Entity::from_bits(graphics_id);
+    error::check(|| {
+        graphics_record_command(
+            graphics_entity,
+            DrawCommand::StrokeJoin(processing::prelude::StrokeJoinMode::from(join)),
+        )
+    });
+}
+
 /// Disable fill for subsequent shapes.
 ///
 /// SAFETY:
@@ -694,6 +720,14 @@ pub const PROCESSING_TOPOLOGY_LINE_STRIP: u8 = 2;
 pub const PROCESSING_TOPOLOGY_TRIANGLE_LIST: u8 = 3;
 pub const PROCESSING_TOPOLOGY_TRIANGLE_STRIP: u8 = 4;
 
+pub const PROCESSING_STROKE_CAP_ROUND: u8 = 0;
+pub const PROCESSING_STROKE_CAP_SQUARE: u8 = 1;
+pub const PROCESSING_STROKE_CAP_PROJECT: u8 = 2;
+
+pub const PROCESSING_STROKE_JOIN_ROUND: u8 = 0;
+pub const PROCESSING_STROKE_JOIN_MITER: u8 = 1;
+pub const PROCESSING_STROKE_JOIN_BEVEL: u8 = 2;
+
 #[unsafe(no_mangle)]
 pub extern "C" fn processing_geometry_layout_create() -> u64 {
     error::clear_error();

crates/processing_ffi/src/lib.rs

@@ -319,6 +319,22 @@ impl Graphics {
             .map_err(|e| PyRuntimeError::new_err(format!("{e}")))
     }
 
+    pub fn stroke_cap(&self, cap: u8) -> PyResult<()> {
+        graphics_record_command(
+            self.entity,
+            DrawCommand::StrokeCap(processing::prelude::StrokeCapMode::from(cap)),
+        )
+        .map_err(|e| PyRuntimeError::new_err(format!("{e}")))
+    }
+
+    pub fn stroke_join(&self, join: u8) -> PyResult<()> {
+        graphics_record_command(
+            self.entity,
+            DrawCommand::StrokeJoin(processing::prelude::StrokeJoinMode::from(join)),
+        )
+        .map_err(|e| PyRuntimeError::new_err(format!("{e}")))
+    }
+
     pub fn rect(
         &self,
         x: f32,

crates/processing_pyo3/src/graphics.rs

@@ -70,6 +70,16 @@ fn processing(m: &Bound<'_, PyModule>) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(stroke, m)?)?;
     m.add_function(wrap_pyfunction!(no_stroke, m)?)?;
     m.add_function(wrap_pyfunction!(stroke_weight, m)?)?;
+    m.add_function(wrap_pyfunction!(stroke_cap, m)?)?;
+    m.add_function(wrap_pyfunction!(stroke_join, m)?)?;
+
+    m.add("ROUND", 0u8)?;
+    m.add("SQUARE", 1u8)?;
+    m.add("PROJECT", 2u8)?;
+
+    m.add("MITER", 1u8)?;
+    m.add("BEVEL", 2u8)?;
+
     m.add_function(wrap_pyfunction!(rect, m)?)?;
     m.add_function(wrap_pyfunction!(image, m)?)?;
     m.add_function(wrap_pyfunction!(draw_geometry, m)?)?;
@@ -435,6 +445,18 @@ fn stroke_weight(module: &Bound<'_, PyModule>, weight: f32) -> PyResult<()> {
     graphics!(module).stroke_weight(weight)
 }
 
+#[pyfunction]
+#[pyo3(pass_module)]
+fn stroke_cap(module: &Bound<'_, PyModule>, cap: u8) -> PyResult<()> {
+    graphics!(module).stroke_cap(cap)
+}
+
+#[pyfunction]
+#[pyo3(pass_module)]
+fn stroke_join(module: &Bound<'_, PyModule>, join: u8) -> PyResult<()> {
+    graphics!(module).stroke_join(join)
+}
+
 #[pyfunction]
 #[pyo3(pass_module, signature = (x, y, w, h, tl=0.0, tr=0.0, br=0.0, bl=0.0))]
 fn rect(

crates/processing_pyo3/src/lib.rs

@@ -279,6 +279,7 @@ fn create_app(config: Config) -> App {
         LightPlugin,
         material::MaterialPlugin,
         MidiPlugin,
+        bevy::pbr::wireframe::WireframePlugin::default(),
         material::custom::CustomMaterialPlugin,
     ));
     app.add_systems(First, (clear_transient_meshes, activate_cameras))

crates/processing_render/src/lib.rs

@@ -1,5 +1,45 @@
 use bevy::prelude::*;
 
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
+#[repr(u8)]
+pub enum StrokeCapMode {
+    #[default]
+    Round = 0,
+    Square = 1,
+    Project = 2,
+}
+
+impl From<u8> for StrokeCapMode {
+    fn from(v: u8) -> Self {
+        match v {
+            0 => Self::Round,
+            1 => Self::Square,
+            2 => Self::Project,
+            _ => Self::default(),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
+#[repr(u8)]
+pub enum StrokeJoinMode {
+    #[default]
+    Round = 0,
+    Miter = 1,
+    Bevel = 2,
+}
+
+impl From<u8> for StrokeJoinMode {
+    fn from(v: u8) -> Self {
+        match v {
+            0 => Self::Round,
+            1 => Self::Miter,
+            2 => Self::Bevel,
+            _ => Self::default(),
+        }
+    }
+}
+
 #[derive(Debug, Clone)]
 pub enum DrawCommand {
     BackgroundColor(Color),
@@ -9,6 +49,8 @@ pub enum DrawCommand {
     StrokeColor(Color),
     NoStroke,
     StrokeWeight(f32),
+    StrokeCap(StrokeCapMode),
+    StrokeJoin(StrokeJoinMode),
     Roughness(f32),
     Metallic(f32),
     Emissive(Color),

crates/processing_render/src/render/command.rs

@@ -12,7 +12,7 @@ use bevy::{
 };
 use command::{CommandBuffer, DrawCommand};
 use material::MaterialKey;
-use primitive::{TessellationMode, box_mesh, empty_mesh, sphere_mesh};
+use primitive::{StrokeConfig, TessellationMode, box_mesh, empty_mesh, sphere_mesh};
 use transform::TransformStack;
 
 use crate::{
@@ -65,6 +65,7 @@ pub struct RenderState {
     pub fill_color: Option<Color>,
     pub stroke_color: Option<Color>,
     pub stroke_weight: f32,
+    pub stroke_config: StrokeConfig,
     pub material_key: MaterialKey,
     pub transform: TransformStack,
 }
@@ -75,6 +76,7 @@ impl RenderState {
             fill_color: Some(Color::WHITE),
             stroke_color: Some(Color::BLACK),
             stroke_weight: 1.0,
+            stroke_config: StrokeConfig::default(),
             material_key: MaterialKey::Color {
                 transparent: false,
                 background_image: None,
@@ -87,6 +89,7 @@ impl RenderState {
         self.fill_color = Some(Color::WHITE);
         self.stroke_color = Some(Color::BLACK);
         self.stroke_weight = 1.0;
+        self.stroke_config = StrokeConfig::default();
         self.material_key = MaterialKey::Color {
             transparent: false,
             background_image: None,
@@ -152,6 +155,12 @@ pub fn flush_draw_commands(
                 DrawCommand::StrokeWeight(weight) => {
                     state.stroke_weight = weight;
                 }
+                DrawCommand::StrokeCap(cap) => {
+                    state.stroke_config.line_cap = cap;
+                }
+                DrawCommand::StrokeJoin(join) => {
+                    state.stroke_config.line_join = join;
+                }
                 DrawCommand::Roughness(r) => {
                     state.material_key = match state.material_key {
                         MaterialKey::Pbr {
@@ -223,11 +232,24 @@ pub fn flush_draw_commands(
                     };
                 }
                 DrawCommand::Rect { x, y, w, h, radii } => {
+                    let stroke_config = state.stroke_config;
                     add_fill(
                         &mut res,
                         &mut batch,
                         &state,
-                        |mesh, color| rect(mesh, x, y, w, h, radii, color, TessellationMode::Fill),
+                        |mesh, color| {
+                            rect(
+                                mesh,
+                                x,
+                                y,
+                                w,
+                                h,
+                                radii,
+                                color,
+                                TessellationMode::Fill,
+                                &stroke_config,
+                            )
+                        },
                         &p_material_handles,
                     );
 
@@ -245,6 +267,7 @@ pub fn flush_draw_commands(
                                 radii,
                                 color,
                                 TessellationMode::Stroke(weight),
+                                &stroke_config,
                             )
                         },
                         &p_material_handles,
@@ -556,34 +579,68 @@ fn add_shape3d(
     mesh: Mesh,
     material_handles: &Query<&UntypedMaterial>,
 ) {
+    use bevy::pbr::wireframe::{Wireframe, WireframeColor, WireframeLineWidth, WireframeTopology};
+
     flush_batch(res, batch, material_handles);
 
     let mesh_handle = res.meshes.add(mesh);
-    let material_key = material_key_with_fill(state);
-
-    let material_handle = match &material_key {
+    let fill_color = state.fill_color.unwrap_or(Color::WHITE);
+    let material_handle = match &state.material_key {
         MaterialKey::Custom(entity) => match material_handles.get(*entity) {
             Ok(handle) => handle.0.clone(),
             Err(_) => {
                 warn!("Custom material entity {:?} not found", entity);
                 return;
             }
         },
-        _ => material_key.to_material(&mut res.materials),
+        // TODO: in 2d, we use vertex colors. `to_material` becomes complicated if we also encode
+        // a base color in the material, so for simplicity we just create a new material here
+        // that is unlit and uses the fill color as the base color
+        MaterialKey::Color { transparent, .. } => {
+            let mat = StandardMaterial {
+                base_color: fill_color,
+                unlit: true,
+                cull_mode: None,
+                alpha_mode: if *transparent {
+                    AlphaMode::Blend
+                } else {
+                    AlphaMode::Opaque
+                },
+                ..default()
+            };
+            res.materials.add(mat).untyped()
+        }
+        _ => {
+            let key = material_key_with_fill(state);
+            key.to_material(&mut res.materials)
+        }
     };
 
     let z_offset = -(batch.draw_index as f32 * 0.001);
     let mut transform = state.transform.to_bevy_transform();
     transform.translation.z += z_offset;
 
-    res.commands.spawn((
+    let mut entity = res.commands.spawn((
         Mesh3d(mesh_handle),
         UntypedMaterial(material_handle),
         BelongsToGraphics(batch.graphics_entity),
         transform,
         batch.render_layers.clone(),
     ));
 
+    if let Some(stroke_color) = state.stroke_color {
+        entity.insert((
+            Wireframe,
+            WireframeColor {
+                color: stroke_color,
+            },
+            WireframeLineWidth {
+                width: state.stroke_weight,
+            },
+            WireframeTopology::Quads,
+        ));
+    }
+
     batch.draw_index += 1;
 }