overflow: hidden/scroll scissor support, remove depth

wgui/src/stack.rs

@@ -0,0 +1,108 @@
+use glam::Vec2;
+
+use crate::drawing;
+
+pub trait Pushable<T> {
+	fn push(&mut self, item: &T);
+}
+
+pub struct GenericStack<T, const STACK_MAX: usize> {
+	pub stack: [T; STACK_MAX],
+	top: u8,
+}
+
+pub trait StackItem<T>: Default + Clone + Copy + Pushable<T> {}
+
+impl<T: StackItem<T>, const STACK_MAX: usize> GenericStack<T, STACK_MAX> {
+	pub fn new() -> Self {
+		Self {
+			stack: [Default::default(); STACK_MAX],
+			top: 1,
+		}
+	}
+
+	pub fn push(&mut self, mut item: T) {
+		assert!(self.top < STACK_MAX as u8);
+		let idx = (self.top - 1) as usize;
+		let upper_item = &self.stack[idx];
+		item.push(upper_item);
+		self.stack[self.top as usize] = item;
+		self.top += 1;
+	}
+
+	pub fn pop(&mut self) {
+		assert!(self.top > 0);
+		self.top -= 1;
+	}
+
+	pub const fn get(&self) -> &T {
+		&self.stack[(self.top - 1) as usize]
+	}
+}
+
+impl<T: StackItem<T>, const STACK_MAX: usize> Default for GenericStack<T, STACK_MAX> {
+	fn default() -> Self {
+		Self::new()
+	}
+}
+
+// ########################################
+// Transform stack
+// ########################################
+
+#[derive(Default, Copy, Clone)]
+pub struct Transform {
+	pub pos: Vec2,
+	pub transform: glam::Mat4,
+	pub dim: Vec2, // for convenience
+}
+
+impl<T> StackItem<T> for Transform where Transform: Pushable<T> {}
+
+impl Pushable<Transform> for Transform {
+	fn push(&mut self, upper: &Transform) {
+		self.pos += upper.pos;
+	}
+}
+
+pub type TransformStack = GenericStack<Transform, 64>;
+
+// ########################################
+// Scissor stack
+// ########################################
+
+impl<T> StackItem<T> for drawing::Boundary where drawing::Boundary: Pushable<T> {}
+
+impl Pushable<drawing::Boundary> for drawing::Boundary {
+	fn push(&mut self, upper: &drawing::Boundary) {
+		let mut display_pos = self.pos;
+		let mut display_size = self.size;
+
+		// limit in x-coord
+		if display_pos.x < upper.left() {
+			display_size.x -= upper.left() - display_pos.x;
+			display_pos.x = upper.left();
+		}
+
+		// limit in y-coord
+		if display_pos.y < upper.top() {
+			display_size.y -= upper.top() - display_pos.y;
+			display_pos.y = upper.top();
+		}
+
+		// limit in width
+		if display_pos.x + display_size.x > upper.right() {
+			display_size.x = upper.right() - display_pos.x;
+		}
+
+		// limit in height
+		if display_pos.y + display_size.y > upper.bottom() {
+			display_size.y = upper.bottom() - display_pos.y;
+		}
+
+		self.pos = display_pos;
+		self.size = display_size;
+	}
+}
+
+pub type ScissorStack = GenericStack<drawing::Boundary, 64>;