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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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21
egui_demo_lib/src/apps/fractal_clock.rs
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@@ -100,8 +100,6 @@ impl FractalClock {
}
fn paint(&mut self, painter: &Painter) {
let rect = painter.clip_rect();
struct Hand {
length: f32,
angle: f32,
@@ -130,14 +128,18 @@ impl FractalClock {
Hand::from_length_angle(0.5, angle_from_period(12.0 * 60.0 * 60.0)),
];
let scale = self.zoom * rect.width().min(rect.height());
let mut shapes: Vec<Shape> = Vec::new();
let mut paint_line = |points: [Pos2; 2], color: Color32, width: f32| {
let line = [
rect.center() + scale * points[0].to_vec2(),
rect.center() + scale * points[1].to_vec2(),
];
let rect = painter.clip_rect();
let to_screen = emath::RectTransform::from_to(
Rect::from_center_size(Pos2::ZERO, rect.square_proportions() / self.zoom),
rect,
);
let mut paint_line = |points: [Pos2; 2], color: Color32, width: f32| {
let line = [to_screen * points[0], to_screen * points[1]];
// culling
if rect.intersects(Rect::from_two_pos(line[0], line[1])) {
shapes.push(Shape::line_segment(line, (width, color)));
}
@@ -186,6 +188,9 @@ impl FractalClock {
width *= self.width_factor;
let luminance_u8 = (255.0 * luminance).round() as u8;
if luminance_u8 == 0 {
break;
}
for &rotor in &hand_rotors {
for a in &nodes {