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mkalte666mkalte666
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Add logarithmic plot axes
This commit is an initial implementation for adding logarithmic plotting axis. This very much needs more testing! The basic idea is, that everything stays the same, but PlotTransform does the much needed coordinate transformation for us. That is, unfortunatley not all of the story. * In a lot of places, we need estimates of "how many pixels does 1 plot space unit take" and the likes, either for overdraw reduction, or generally to size things. PlotTransform has been modifed for that for now, so this should work. * While the normal grid spacer renders just fine, it will also casually try to generate 100s of thousands of lines for a bigger range log plot. So GridInput has been made aware if there is a log axis present. The default spacer has also been modified to work initially. * All of the PlotBound transformations within PlotTransform need to be aware and handle the log scaling properly. This is done and works well, but its a bit.. icky, for lack of a better word. If someone has a better idea how to handle this, be my guest :D * PlotPoint generation from generator functions has to become aware of logarithmic plotting, otherwise the resolution of the plotted points will suffer. Especially the spacer generation is still kinda WIP; it is messy at best right now. Especially for zooming in, it currently only adds lines on the lower bound due to the way the generator function works right now. I will address this in a follow up commit/--amend (or someone else will).
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-111
lines changed

9 files changed

+493
-111
lines changed

‎demo/src/plot_demo.rs‎

Lines changed: 78 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,8 +7,8 @@ use egui::{
77

88
use egui_plot::{
99
Arrows, AxisHints, Bar, BarChart, BoxElem, BoxPlot, BoxSpread, CoordinatesFormatter, Corner,
10-
GridInput, GridMark, HLine, Legend, Line, LineStyle, MarkerShape, Plot, PlotImage, PlotPoint,
11-
PlotPoints, PlotResponse, Points, Polygon, Text, VLine,
10+
GridInput, GridMark, HLine, Legend, Line, LineStyle, MarkerShape, Plot, PlotBounds, PlotImage,
11+
PlotPoint, PlotPoints, PlotResponse, Points, Polygon, Text, VLine,
1212
};
1313

1414
// ----------------------------------------------------------------------------
@@ -23,6 +23,7 @@ enum Panel {
2323
Interaction,
2424
CustomAxes,
2525
LinkedAxes,
26+
LogAxes,
2627
}
2728

2829
impl Default for Panel {
@@ -43,6 +44,7 @@ pub struct PlotDemo {
4344
interaction_demo: InteractionDemo,
4445
custom_axes_demo: CustomAxesDemo,
4546
linked_axes_demo: LinkedAxesDemo,
47+
log_axes_demo: LogAxesDemo,
4648
open_panel: Panel,
4749
}
4850

@@ -74,6 +76,7 @@ impl PlotDemo {
7476
ui.selectable_value(&mut self.open_panel, Panel::Interaction, "Interaction");
7577
ui.selectable_value(&mut self.open_panel, Panel::CustomAxes, "Custom Axes");
7678
ui.selectable_value(&mut self.open_panel, Panel::LinkedAxes, "Linked Axes");
79+
ui.selectable_value(&mut self.open_panel, Panel::LogAxes, "Log Axes");
7780
});
7881
ui.separator();
7982

@@ -102,6 +105,9 @@ impl PlotDemo {
102105
Panel::LinkedAxes => {
103106
self.linked_axes_demo.ui(ui);
104107
}
108+
Panel::LogAxes => {
109+
self.log_axes_demo.ui(ui);
110+
}
105111
}
106112
}
107113
}
@@ -691,6 +697,76 @@ impl LinkedAxesDemo {
691697
}
692698
}
693699

700+
// ----------------------------------------------------------------------------
701+
#[derive(PartialEq, serde::Deserialize, serde::Serialize)]
702+
struct LogAxesDemo {
703+
log_axes: Vec2b,
704+
}
705+
706+
impl Default for LogAxesDemo {
707+
fn default() -> Self {
708+
Self {
709+
log_axes: Vec2b::new(false, true),
710+
}
711+
}
712+
}
713+
714+
impl LogAxesDemo {
715+
fn line_exp() -> Line {
716+
Line::new(PlotPoints::from_explicit_callback(
717+
move |x| 10.0_f64.powf(x / 200.0),
718+
0.1..=1000.0,
719+
1000,
720+
))
721+
.name("y = 10^(x/200)")
722+
.color(Color32::RED)
723+
}
724+
725+
fn line_lin() -> Line {
726+
Line::new(PlotPoints::from_explicit_callback(
727+
move |x| -5.0 + x,
728+
0.1..=1000.0,
729+
1000,
730+
))
731+
.name("y = -5 + x")
732+
.color(Color32::GREEN)
733+
}
734+
735+
fn line_log() -> Line {
736+
Line::new(PlotPoints::from_explicit_callback(
737+
move |x| x.log10(),
738+
0.1..=1000.0,
739+
1000,
740+
))
741+
.name("y = log10(x)")
742+
.color(Color32::BLUE)
743+
}
744+
745+
fn ui(&mut self, ui: &mut egui::Ui) -> Response {
746+
let just_changed = ui.checkbox(&mut self.log_axes.x, "Log X-Axis").clicked();
747+
ui.checkbox(&mut self.log_axes.y, "Log Y-Axis");
748+
Plot::new("log_demo")
749+
.log_axes(self.log_axes)
750+
.x_axis_label("x")
751+
.y_axis_label("y")
752+
.show_axes(Vec2b::new(true, true))
753+
.legend(Legend::default())
754+
.show(ui, |ui| {
755+
if just_changed {
756+
if self.log_axes.x {
757+
ui.set_plot_bounds(PlotBounds::from_min_max([0.1, 0.1], [1e3, 1e4]));
758+
} else {
759+
ui.set_plot_bounds(PlotBounds::from_min_max([0.0, 0.0], [3.0, 1000.0]));
760+
}
761+
}
762+
ui.line(Self::line_exp());
763+
ui.line(Self::line_lin());
764+
ui.line(Self::line_log());
765+
})
766+
.response
767+
}
768+
}
769+
694770
// ----------------------------------------------------------------------------
695771

696772
#[derive(Default, PartialEq, serde::Deserialize, serde::Serialize)]

‎egui_plot/src/axis.rs‎

Lines changed: 5 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -339,8 +339,11 @@ impl<'a> AxisWidget<'a> {
339339
for step in self.steps.iter() {
340340
let text = (self.hints.formatter)(*step, &self.range);
341341
if !text.is_empty() {
342-
let spacing_in_points =
343-
(transform.dpos_dvalue()[usize::from(axis)] * step.step_size).abs() as f32;
342+
let spacing_in_points = transform.points_at_pos_range(
343+
[step.value, step.value],
344+
[step.step_size, step.step_size],
345+
)[usize::from(axis)]
346+
.abs();
344347

345348
if spacing_in_points <= label_spacing.min {
346349
// Labels are too close together - don't paint them.

‎egui_plot/src/items/bar.rs‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -186,7 +186,7 @@ impl RectElement for Bar {
186186
}
187187

188188
fn default_values_format(&self, transform: &PlotTransform) -> String {
189-
let scale = transform.dvalue_dpos();
189+
let scale = transform.smallest_distance_per_point();
190190
let scale = match self.orientation {
191191
Orientation::Horizontal => scale[0],
192192
Orientation::Vertical => scale[1],

‎egui_plot/src/items/box_elem.rs‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -271,7 +271,7 @@ impl RectElement for BoxElem {
271271
}
272272

273273
fn default_values_format(&self, transform: &PlotTransform) -> String {
274-
let scale = transform.dvalue_dpos();
274+
let scale = transform.smallest_distance_per_point();
275275
let scale = match self.orientation {
276276
Orientation::Horizontal => scale[0],
277277
Orientation::Vertical => scale[1],

‎egui_plot/src/items/mod.rs‎

Lines changed: 18 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -41,7 +41,7 @@ pub trait PlotItem {
4141
fn shapes(&self, ui: &Ui, transform: &PlotTransform, shapes: &mut Vec<Shape>);
4242

4343
/// For plot-items which are generated based on x values (plotting functions).
44-
fn initialize(&mut self, x_range: RangeInclusive<f64>);
44+
fn initialize(&mut self, x_range: RangeInclusive<f64>, log_base: Option<f64>);
4545

4646
fn name(&self) -> &str;
4747

@@ -233,7 +233,7 @@ impl PlotItem for HLine {
233233
style.style_line(points, *stroke, *highlight, shapes);
234234
}
235235

236-
fn initialize(&mut self, _x_range: RangeInclusive<f64>) {}
236+
fn initialize(&mut self, _x_range: RangeInclusive<f64>, _log_base: Option<f64>) {}
237237

238238
fn name(&self) -> &str {
239239
&self.name
@@ -381,7 +381,7 @@ impl PlotItem for VLine {
381381
style.style_line(points, *stroke, *highlight, shapes);
382382
}
383383

384-
fn initialize(&mut self, _x_range: RangeInclusive<f64>) {}
384+
fn initialize(&mut self, _x_range: RangeInclusive<f64>, _log_base: Option<f64>) {}
385385

386386
fn name(&self) -> &str {
387387
&self.name
@@ -591,8 +591,8 @@ impl PlotItem for Line {
591591
style.style_line(values_tf, *stroke, *highlight, shapes);
592592
}
593593

594-
fn initialize(&mut self, x_range: RangeInclusive<f64>) {
595-
self.series.generate_points(x_range);
594+
fn initialize(&mut self, x_range: RangeInclusive<f64>, log_base: Option<f64>) {
595+
self.series.generate_points(x_range, log_base);
596596
}
597597

598598
fn name(&self) -> &str {
@@ -747,8 +747,8 @@ impl PlotItem for Polygon {
747747
style.style_line(values_tf, *stroke, *highlight, shapes);
748748
}
749749

750-
fn initialize(&mut self, x_range: RangeInclusive<f64>) {
751-
self.series.generate_points(x_range);
750+
fn initialize(&mut self, x_range: RangeInclusive<f64>, log_base: Option<f64>) {
751+
self.series.generate_points(x_range, log_base);
752752
}
753753

754754
fn name(&self) -> &str {
@@ -889,7 +889,7 @@ impl PlotItem for Text {
889889
}
890890
}
891891

892-
fn initialize(&mut self, _x_range: RangeInclusive<f64>) {}
892+
fn initialize(&mut self, _x_range: RangeInclusive<f64>, _log_base: Option<f64>) {}
893893

894894
fn name(&self) -> &str {
895895
self.name.as_str()
@@ -1167,8 +1167,8 @@ impl PlotItem for Points {
11671167
});
11681168
}
11691169

1170-
fn initialize(&mut self, x_range: RangeInclusive<f64>) {
1171-
self.series.generate_points(x_range);
1170+
fn initialize(&mut self, x_range: RangeInclusive<f64>, log_base: Option<f64>) {
1171+
self.series.generate_points(x_range, log_base);
11721172
}
11731173

11741174
fn name(&self) -> &str {
@@ -1322,10 +1322,11 @@ impl PlotItem for Arrows {
13221322
});
13231323
}
13241324

1325-
fn initialize(&mut self, _x_range: RangeInclusive<f64>) {
1325+
fn initialize(&mut self, _x_range: RangeInclusive<f64>, log_base: Option<f64>) {
13261326
self.origins
1327-
.generate_points(f64::NEG_INFINITY..=f64::INFINITY);
1328-
self.tips.generate_points(f64::NEG_INFINITY..=f64::INFINITY);
1327+
.generate_points(f64::NEG_INFINITY..=f64::INFINITY, log_base);
1328+
self.tips
1329+
.generate_points(f64::NEG_INFINITY..=f64::INFINITY, log_base);
13291330
}
13301331

13311332
fn name(&self) -> &str {
@@ -1514,7 +1515,7 @@ impl PlotItem for PlotImage {
15141515
}
15151516
}
15161517

1517-
fn initialize(&mut self, _x_range: RangeInclusive<f64>) {}
1518+
fn initialize(&mut self, _x_range: RangeInclusive<f64>, _log_base: Option<f64>) {}
15181519

15191520
fn name(&self) -> &str {
15201521
self.name.as_str()
@@ -1709,7 +1710,7 @@ impl PlotItem for BarChart {
17091710
}
17101711
}
17111712

1712-
fn initialize(&mut self, _x_range: RangeInclusive<f64>) {
1713+
fn initialize(&mut self, _x_range: RangeInclusive<f64>, _log_base: Option<f64>) {
17131714
// nothing to do
17141715
}
17151716

@@ -1883,7 +1884,7 @@ impl PlotItem for BoxPlot {
18831884
}
18841885
}
18851886

1886-
fn initialize(&mut self, _x_range: RangeInclusive<f64>) {
1887+
fn initialize(&mut self, _x_range: RangeInclusive<f64>, _log_base: Option<f64>) {
18871888
// nothing to do
18881889
}
18891890

@@ -2069,7 +2070,7 @@ pub(super) fn rulers_at_value(
20692070
};
20702071

20712072
let text = {
2072-
let scale = plot.transform.dvalue_dpos();
2073+
let scale = plot.transform.smallest_distance_per_point();
20732074
let x_decimals = ((-scale[0].abs().log10()).ceil().at_least(0.0) as usize).clamp(1, 6);
20742075
let y_decimals = ((-scale[1].abs().log10()).ceil().at_least(0.0) as usize).clamp(1, 6);
20752076
if let Some(custom_label) = label_formatter {

‎egui_plot/src/items/values.rs‎

Lines changed: 17 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -276,15 +276,28 @@ impl PlotPoints {
276276

277277
/// If initialized with a generator function, this will generate `n` evenly spaced points in the
278278
/// given range.
279-
pub(super) fn generate_points(&mut self, x_range: RangeInclusive<f64>) {
279+
pub(super) fn generate_points(&mut self, x_range: RangeInclusive<f64>, log_base: Option<f64>) {
280280
if let Self::Generator(generator) = self {
281281
*self = Self::range_intersection(&x_range, &generator.x_range)
282282
.map(|intersection| {
283-
let increment =
284-
(intersection.end() - intersection.start()) / (generator.points - 1) as f64;
283+
let increment = match log_base {
284+
Some(base) => {
285+
(intersection.end().log(base) - intersection.start().log(base))
286+
/ (generator.points - 1) as f64
287+
}
288+
None => {
289+
(intersection.end() - intersection.start())
290+
/ (generator.points - 1) as f64
291+
}
292+
};
285293
(0..generator.points)
286294
.map(|i| {
287-
let x = intersection.start() + i as f64 * increment;
295+
let x = match log_base {
296+
Some(base) => {
297+
base.powf(intersection.start().log(base) + i as f64 * increment)
298+
}
299+
None => intersection.start() + i as f64 * increment,
300+
};
288301
let y = (generator.function)(x);
289302
[x, y]
290303
})

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