overflow: hidden/scroll scissor support, remove depth

wgui/src/drawing.rs

@@ -8,7 +8,7 @@ use crate::{
 	drawing,
 	layout::Widget,
 	renderer_vk::text::custom_glyph::CustomGlyph,
-	transform_stack::{self, TransformStack},
+	stack::{self, ScissorStack, TransformStack},
 	widget::{self},
 };
 
@@ -37,6 +37,22 @@ impl Boundary {
 			size: Vec2::new(transform.dim.x, transform.dim.y),
 		}
 	}
+
+	pub const fn top(&self) -> f32 {
+		self.pos.y
+	}
+
+	pub const fn bottom(&self) -> f32 {
+		self.pos.y + self.size.y
+	}
+
+	pub const fn left(&self) -> f32 {
+		self.pos.x
+	}
+
+	pub const fn right(&self) -> f32 {
+		self.pos.x + self.size.x
+	}
 }
 
 #[derive(Debug, Copy, Clone)]
@@ -115,7 +131,6 @@ pub struct Rectangle {
 pub struct PrimitiveExtent {
 	pub(super) boundary: Boundary,
 	pub(super) transform: Mat4,
-	pub(super) depth: f32, // FIXME: remove this
 }
 
 pub enum RenderPrimitive {
@@ -126,15 +141,39 @@ pub enum RenderPrimitive {
 	ScissorDisable,
 }
 
+pub struct DrawParams<'a> {
+	pub layout: &'a Layout,
+	pub debug_draw: bool,
+}
+
+fn has_overflow_clip(style: &taffy::Style) -> bool {
+	style.overflow.x != taffy::Overflow::Visible || style.overflow.y != taffy::Overflow::Visible
+}
+
+fn primitive_debug_rect(boundary: &Boundary, transform: &Mat4, color: drawing::Color) -> drawing::RenderPrimitive {
+	drawing::RenderPrimitive::Rectangle(
+		PrimitiveExtent {
+			boundary: *boundary,
+			transform: *transform,
+		},
+		Rectangle {
+			border: 1.0,
+			border_color: color,
+			color: Color::new(0.0, 0.0, 0.0, 0.0),
+			..Default::default()
+		},
+	)
+}
+
 fn draw_widget(
-	layout: &Layout,
+	params: &DrawParams,
 	state: &mut DrawState,
 	node_id: taffy::NodeId,
 	style: &taffy::Style,
 	widget: &Widget,
 	parent_transform: &glam::Mat4,
 ) {
-	let Ok(l) = layout.state.tree.layout(node_id) else {
+	let Ok(l) = params.layout.state.tree.layout(node_id) else {
 		debug_assert!(false);
 		return;
 	};
@@ -148,16 +187,34 @@ fn draw_widget(
 		None => (Vec2::default(), None),
 	};
 
-	state.transform_stack.push(transform_stack::Transform {
+	state.transform_stack.push(stack::Transform {
 		pos: Vec2::new(l.location.x, l.location.y) - shift,
 		transform,
 		dim: Vec2::new(l.size.width, l.size.height),
 	});
 
-	// FIXME: this is temporary
-	// FIXME: implement scissor stack (do not allow growing!)
-	if info.is_some() {
+	if params.debug_draw {
 		let boundary = drawing::Boundary::construct(state.transform_stack);
+		state.primitives.push(primitive_debug_rect(
+			&boundary,
+			&transform,
+			Color::new(0.0, 1.0, 1.0, 0.5),
+		));
+	}
+
+	let scissor_pushed = info.is_some() && has_overflow_clip(style);
+
+	if scissor_pushed {
+		let boundary = drawing::Boundary::construct(state.transform_stack);
+		state.scissor_stack.push(boundary);
+		if params.debug_draw {
+			state.primitives.push(primitive_debug_rect(
+				&boundary,
+				&transform,
+				Color::new(1.0, 0.0, 1.0, 1.0),
+			));
+		}
+
 		state.primitives.push(drawing::RenderPrimitive::ScissorEnable(boundary));
 	}
 
@@ -169,10 +226,11 @@ fn draw_widget(
 
 	widget_state.draw_all(state, &draw_params);
 
-	draw_children(layout, state, node_id, &transform);
+	draw_children(params, state, node_id, &transform);
 
-	if info.is_some() {
+	if scissor_pushed {
 		state.primitives.push(drawing::RenderPrimitive::ScissorDisable);
+		state.scissor_stack.pop();
 	}
 
 	state.transform_stack.pop();
@@ -182,7 +240,9 @@ fn draw_widget(
 	}
 }
 
-fn draw_children(layout: &Layout, state: &mut DrawState, parent_node_id: taffy::NodeId, model: &glam::Mat4) {
+fn draw_children(params: &DrawParams, state: &mut DrawState, parent_node_id: taffy::NodeId, model: &glam::Mat4) {
+	let layout = &params.layout;
+
 	for node_id in layout.state.tree.child_ids(parent_node_id) {
 		let Some(widget_id) = layout.state.tree.get_node_context(node_id).copied() else {
 			debug_assert!(false);
@@ -199,33 +259,37 @@ fn draw_children(layout: &Layout, state: &mut DrawState, parent_node_id: taffy::
 			continue;
 		};
 
-		state.depth += 0.01;
-		draw_widget(layout, state, node_id, style, widget, model);
-		state.depth -= 0.01;
+		draw_widget(params, state, node_id, style, widget, model);
 	}
 }
 
-pub fn draw(layout: &Layout) -> anyhow::Result<Vec<RenderPrimitive>> {
+pub fn draw(params: &DrawParams) -> anyhow::Result<Vec<RenderPrimitive>> {
 	let mut primitives = Vec::<RenderPrimitive>::new();
 	let mut transform_stack = TransformStack::new();
+	let mut scissor_stack = ScissorStack::new();
 	let model = glam::Mat4::IDENTITY;
 
-	let Some(root_widget) = layout.state.widgets.get(layout.root_widget) else {
+	let Some(root_widget) = params.layout.state.widgets.get(params.layout.root_widget) else {
 		panic!();
 	};
 
-	let Ok(style) = layout.state.tree.style(layout.root_node) else {
+	let Ok(style) = params.layout.state.tree.style(params.layout.root_node) else {
 		panic!();
 	};
 
-	let mut params = DrawState {
+	scissor_stack.push(Boundary {
+		pos: Default::default(),
+		size: Vec2::splat(1.0e12),
+	});
+
+	let mut state = DrawState {
 		primitives: &mut primitives,
 		transform_stack: &mut transform_stack,
-		layout,
-		depth: 0.0,
+		scissor_stack: &mut scissor_stack,
+		layout: params.layout,
 	};
 
-	draw_widget(layout, &mut params, layout.root_node, style, root_widget, &model);
+	draw_widget(params, &mut state, params.layout.root_node, style, root_widget, &model);
 
 	Ok(primitives)
 }