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[emath] RectTransform: transforms Pos2 from one Rect to another

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Very useful for transforming coordinate systems, e.g. for painting
This commit is contained in:
Emil Ernerfeldt
2021-02-14 10:33:44 +01:00
parent dbc6a620cd
commit c376d0bb7e
8 changed files with 142 additions and 24 deletions
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9
egui_demo_lib/src/apps/demo/dancing_strings.rs
View File

@@ -34,6 +34,9 @@ impl super::View for DancingStrings {
let desired_size = ui.available_width() * vec2(1.0, 0.35);
let (_id, rect) = ui.allocate_space(desired_size);
let to_screen =
math::RectTransform::from_to(Rect::from_x_y_ranges(0.0..=1.0, -1.0..=1.0), rect);
let mut shapes = vec![];
for &mode in &[2, 3, 5] {
@@ -46,11 +49,7 @@ impl super::View for DancingStrings {
let t = i as f32 / (n as f32);
let amp = (time as f32 * speed * mode).sin() / mode;
let y = amp * (t * std::f32::consts::TAU / 2.0 * mode).sin();
pos2(
lerp(rect.x_range(), t),
remap(y, -1.0..=1.0, rect.y_range()),
)
to_screen * pos2(t, y)
})
.collect();

13
egui_demo_lib/src/apps/demo/painting.rs
View File

@@ -3,7 +3,8 @@ use egui::*;
#[cfg_attr(feature = "persistence", derive(serde::Deserialize, serde::Serialize))]
#[cfg_attr(feature = "persistence", serde(default))]
pub struct Painting {
lines: Vec<Vec<Vec2>>,
/// in 0-1 normalized coordinates
lines: Vec<Vec<Pos2>>,
stroke: Stroke,
}
@@ -32,6 +33,12 @@ impl Painting {
ui.allocate_painter(ui.available_size_before_wrap_finite(), Sense::drag());
let rect = response.rect;
let to_screen = emath::RectTransform::from_to(
Rect::from_min_size(Pos2::ZERO, rect.square_proportions()),
rect,
);
let from_screen = to_screen.inverse();
if self.lines.is_empty() {
self.lines.push(vec![]);
}
@@ -39,7 +46,7 @@ impl Painting {
let current_line = self.lines.last_mut().unwrap();
if let Some(pointer_pos) = response.interact_pointer_pos() {
let canvas_pos = pointer_pos - rect.min;
let canvas_pos = from_screen * pointer_pos;
if current_line.last() != Some(&canvas_pos) {
current_line.push(canvas_pos);
}
@@ -49,7 +56,7 @@ impl Painting {
for line in &self.lines {
if line.len() >= 2 {
let points: Vec<Pos2> = line.iter().map(|p| rect.min + *p).collect();
let points: Vec<Pos2> = line.iter().map(|p| to_screen * *p).collect();
painter.add(Shape::line(points, self.stroke));
}
}