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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));
}
}

21
egui_demo_lib/src/apps/fractal_clock.rs
View file

@ -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 {

19
egui_demo_lib/src/frame_history.rs
View file

@ -58,7 +58,6 @@ impl FrameHistory {
fn graph(&mut self, ui: &mut egui::Ui) -> egui::Response {
use egui::*;
let graph_top_cpu_usage = 0.010;
ui.label("egui CPU usage history");
let history = &self.frame_times;
@ -69,12 +68,17 @@ impl FrameHistory {
let (rect, response) = ui.allocate_at_least(size, Sense::hover());
let style = ui.style().noninteractive();
let mut shapes = vec![Shape::Rect {
let graph_top_cpu_usage = 0.010;
let graph_rect = Rect::from_x_y_ranges(history.max_age()..=0.0, graph_top_cpu_usage..=0.0);
let to_screen = emath::RectTransform::from_to(graph_rect, rect);
let mut shapes = Vec::with_capacity(3 + 2 * history.len());
shapes.push(Shape::Rect {
rect,
corner_radius: style.corner_radius,
fill: ui.visuals().extreme_bg_color,
stroke: ui.style().noninteractive().bg_stroke,
}];
});
let rect = rect.shrink(4.0);
let color = ui.visuals().text_color();
@ -87,7 +91,7 @@ impl FrameHistory {
[pos2(rect.left(), y), pos2(rect.right(), y)],
line_stroke,
));
let cpu_usage = remap(y, rect.bottom_up_range(), 0.0..=graph_top_cpu_usage);
let cpu_usage = to_screen.inverse().transform_pos(pointer_pos).y;
let text = format!("{:.1} ms", 1e3 * cpu_usage);
shapes.push(Shape::text(
ui.fonts(),
@ -106,16 +110,15 @@ impl FrameHistory {
for (time, cpu_usage) in history.iter() {
let age = (right_side_time - time) as f32;
let x = remap(age, history.max_age()..=0.0, rect.x_range());
let y = remap_clamp(cpu_usage, 0.0..=graph_top_cpu_usage, rect.bottom_up_range());
let pos = to_screen.transform_pos_clamped(Pos2::new(age, cpu_usage));
shapes.push(Shape::line_segment(
[pos2(x, rect.bottom()), pos2(x, y)],
[pos2(pos.x, rect.bottom()), pos],
line_stroke,
));
if cpu_usage < graph_top_cpu_usage {
shapes.push(Shape::circle_filled(pos2(x, y), radius, circle_color));
shapes.push(Shape::circle_filled(pos, radius, circle_color));
}
}

2
emath/src/lib.rs
View file

@ -60,6 +60,7 @@ use std::ops::{Add, Div, Mul, RangeInclusive, Sub};
pub mod align;
mod pos2;
mod rect;
mod rect_transform;
mod rot2;
pub mod smart_aim;
mod vec2;
@ -68,6 +69,7 @@ pub use {
align::{Align, Align2},
pos2::*,
rect::*,
rect_transform::*,
rot2::*,
vec2::*,
};

23
emath/src/rect.rs
View file

@ -202,6 +202,29 @@ impl Rect {
pub fn height(&self) -> f32 {
self.max.y - self.min.y
}
/// Width / height
///
/// * `aspect_ratio < 1`: portrait / high
/// * `aspect_ratio = 1`: square
/// * `aspect_ratio > 1`: landscape / wide
pub fn aspect_ratio(&self) -> f32 {
self.width() / self.height()
}
/// `[2, 1]` for wide screen, and `[1, 2]` for portrait, etc.
/// At least one dimension = 1, the other >= 1
/// Returns the proportions required to letter-box a square view area.
pub fn square_proportions(&self) -> Vec2 {
let w = self.width();
let h = self.height();
if w > h {
vec2(w / h, 1.0)
} else {
vec2(1.0, h / w)
}
}
pub fn area(&self) -> f32 {
self.width() * self.height()
}

73
emath/src/rect_transform.rs Normal file
View file

@ -0,0 +1,73 @@
use crate::*;
/// Linearly transforms positions from one [`Rect`] to another.
///
/// `RectTransform` stores the rectangles, and therefore supports clamping and culling.
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct RectTransform {
from: Rect,
to: Rect,
}
impl RectTransform {
pub fn identity(from_and_to: Rect) -> Self {
Self::from_to(from_and_to, from_and_to)
}
pub fn from_to(from: Rect, to: Rect) -> Self {
Self { from, to }
}
pub fn from(&self) -> &Rect {
&self.from
}
pub fn to(&self) -> &Rect {
&self.to
}
pub fn inverse(&self) -> RectTransform {
Self::from_to(self.to, self.from)
}
/// Transforms the given coordinate in the `from` space to the `to` space.
pub fn transform_pos(&self, pos: Pos2) -> Pos2 {
pos2(
remap(pos.x, self.from.x_range(), self.to.x_range()),
remap(pos.y, self.from.y_range(), self.to.y_range()),
)
}
/// Transforms the given rectangle in the `in`-space to a rectangle in the `out`-space.
pub fn transform_rect(&self, rect: Rect) -> Rect {
Rect {
min: self.transform_pos(rect.min),
max: self.transform_pos(rect.max),
}
}
/// Transforms the given coordinate in the `from` space to the `to` space,
/// clamping if necessary.
pub fn transform_pos_clamped(&self, pos: Pos2) -> Pos2 {
pos2(
remap_clamp(pos.x, self.from.x_range(), self.to.x_range()),
remap_clamp(pos.y, self.from.y_range(), self.to.y_range()),
)
}
}
/// Transforms the position.
impl std::ops::Mul<Pos2> for RectTransform {
type Output = Pos2;
fn mul(self, pos: Pos2) -> Pos2 {
self.transform_pos(pos)
}
}
/// Transforms the position.
impl std::ops::Mul<Pos2> for &RectTransform {
type Output = Pos2;
fn mul(self, pos: Pos2) -> Pos2 {
self.transform_pos(pos)
}
}

6
emath/src/rot2.rs
View file

@ -8,7 +8,9 @@ use super::Vec2;
// `vec2(c,s)` represents where the X axis will end up after rotation.
//
/// Represents a rotation in the 2D plane.
//
/// A rotation of 𝞃/4 = 90° rotates the X axis to the Y axis.
//
/// Normally a `Rot2` is normalized (unit-length).
/// If not, it will also scale vectors.
#[derive(Clone, Copy, PartialEq)]
@ -104,6 +106,7 @@ impl std::ops::Mul<Rot2> for Rot2 {
}
}
/// Rotates (and maybe scales) the vector.
impl std::ops::Mul<Vec2> for Rot2 {
type Output = Vec2;
fn mul(self, v: Vec2) -> Vec2 {
@ -114,6 +117,7 @@ impl std::ops::Mul<Vec2> for Rot2 {
}
}
/// Scales the rotor.
impl std::ops::Mul<Rot2> for f32 {
type Output = Rot2;
fn mul(self, r: Rot2) -> Rot2 {
@ -124,6 +128,7 @@ impl std::ops::Mul<Rot2> for f32 {
}
}
/// Scales the rotor.
impl std::ops::Mul<f32> for Rot2 {
type Output = Rot2;
fn mul(self, r: f32) -> Rot2 {
@ -134,6 +139,7 @@ impl std::ops::Mul<f32> for Rot2 {
}
}
/// Scales the rotor.
impl std::ops::Div<f32> for Rot2 {
type Output = Rot2;
fn div(self, r: f32) -> Rot2 {