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color_test.rs
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color_test.rs
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use std::collections::HashMap;
use egui::{color::*, widgets::color_picker::show_color, TextureOptions, *};
const GRADIENT_SIZE: Vec2 = vec2(256.0, 18.0);
const BLACK: Color32 = Color32::BLACK;
const GREEN: Color32 = Color32::GREEN;
const RED: Color32 = Color32::RED;
const TRANSPARENT: Color32 = Color32::TRANSPARENT;
const WHITE: Color32 = Color32::WHITE;
/// A test for sanity-checking and diagnosing egui rendering backends.
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
pub struct ColorTest {
#[cfg_attr(feature = "serde", serde(skip))]
tex_mngr: TextureManager,
vertex_gradients: bool,
texture_gradients: bool,
}
impl Default for ColorTest {
fn default() -> Self {
Self {
tex_mngr: Default::default(),
vertex_gradients: true,
texture_gradients: true,
}
}
}
impl ColorTest {
pub fn ui(&mut self, ui: &mut Ui) {
ui.set_max_width(680.0);
ui.vertical_centered(|ui| {
ui.add(crate::egui_github_link_file!());
});
ui.horizontal_wrapped(|ui|{
ui.label("This is made to test that the egui painter backend is set up correctly.");
ui.add(egui::Label::new("❓").sense(egui::Sense::click()))
.on_hover_text("The texture sampling should be sRGB-aware, and everyt other color operation should be done in gamma-space (sRGB). All colors should use pre-multiplied alpha");
});
ui.label("If the rendering is done right, all groups of gradients will look uniform.");
ui.horizontal(|ui| {
ui.checkbox(&mut self.vertex_gradients, "Vertex gradients");
ui.checkbox(&mut self.texture_gradients, "Texture gradients");
});
ui.heading("sRGB color test");
ui.label("Use a color picker to ensure this color is (255, 165, 0) / #ffa500");
ui.scope(|ui| {
ui.spacing_mut().item_spacing.y = 0.0; // No spacing between gradients
let g = Gradient::one_color(Color32::from_rgb(255, 165, 0));
self.vertex_gradient(ui, "orange rgb(255, 165, 0) - vertex", WHITE, &g);
self.tex_gradient(ui, "orange rgb(255, 165, 0) - texture", WHITE, &g);
});
ui.separator();
ui.label("Test that vertex color times texture color is done in gamma space:");
ui.scope(|ui| {
ui.spacing_mut().item_spacing.y = 0.0; // No spacing between gradients
let tex_color = Color32::from_rgb(64, 128, 255);
let vertex_color = Color32::from_rgb(128, 196, 196);
let ground_truth = mul_color_gamma(tex_color, vertex_color);
ui.horizontal(|ui| {
let color_size = ui.spacing().interact_size;
ui.label("texture");
show_color(ui, tex_color, color_size);
ui.label(" * ");
show_color(ui, vertex_color, color_size);
ui.label(" vertex color =");
});
{
let g = Gradient::one_color(ground_truth);
self.vertex_gradient(ui, "Ground truth (vertices)", WHITE, &g);
self.tex_gradient(ui, "Ground truth (texture)", WHITE, &g);
}
ui.horizontal(|ui| {
let g = Gradient::one_color(tex_color);
let tex = self.tex_mngr.get(ui.ctx(), &g);
let texel_offset = 0.5 / (g.0.len() as f32);
let uv = Rect::from_min_max(pos2(texel_offset, 0.0), pos2(1.0 - texel_offset, 1.0));
ui.add(Image::new(tex, GRADIENT_SIZE).tint(vertex_color).uv(uv))
.on_hover_text(format!("A texture that is {} texels wide", g.0.len()));
ui.label("GPU result");
});
});
ui.separator();
// TODO(emilk): test color multiplication (image tint),
// to make sure vertex and texture color multiplication is done in linear space.
ui.separator();
ui.label("Gamma interpolation:");
self.show_gradients(ui, WHITE, (RED, GREEN), Interpolation::Gamma);
ui.separator();
self.show_gradients(ui, RED, (TRANSPARENT, GREEN), Interpolation::Gamma);
ui.separator();
self.show_gradients(ui, WHITE, (TRANSPARENT, GREEN), Interpolation::Gamma);
ui.separator();
self.show_gradients(ui, BLACK, (BLACK, WHITE), Interpolation::Gamma);
ui.separator();
self.show_gradients(ui, WHITE, (BLACK, TRANSPARENT), Interpolation::Gamma);
ui.separator();
self.show_gradients(ui, BLACK, (TRANSPARENT, WHITE), Interpolation::Gamma);
ui.separator();
ui.label("Additive blending: add more and more blue to the red background:");
self.show_gradients(
ui,
RED,
(TRANSPARENT, Color32::from_rgb_additive(0, 0, 255)),
Interpolation::Gamma,
);
ui.separator();
ui.label("Linear interpolation (texture sampling):");
self.show_gradients(ui, WHITE, (RED, GREEN), Interpolation::Linear);
ui.separator();
pixel_test(ui);
ui.separator();
ui.label("Testing text rendering:");
text_on_bg(ui, Color32::from_gray(200), Color32::from_gray(230)); // gray on gray
text_on_bg(ui, Color32::from_gray(140), Color32::from_gray(28)); // dark mode normal text
// Matches Mac Font book (useful for testing):
text_on_bg(ui, Color32::from_gray(39), Color32::from_gray(255));
text_on_bg(ui, Color32::from_gray(220), Color32::from_gray(30));
ui.separator();
blending_and_feathering_test(ui);
}
fn show_gradients(
&mut self,
ui: &mut Ui,
bg_fill: Color32,
(left, right): (Color32, Color32),
interpolation: Interpolation,
) {
let is_opaque = left.is_opaque() && right.is_opaque();
ui.horizontal(|ui| {
let color_size = ui.spacing().interact_size;
if !is_opaque {
ui.label("Background:");
show_color(ui, bg_fill, color_size);
}
ui.label("gradient");
show_color(ui, left, color_size);
ui.label("-");
show_color(ui, right, color_size);
});
ui.scope(|ui| {
ui.spacing_mut().item_spacing.y = 0.0; // No spacing between gradients
if is_opaque {
let g = Gradient::ground_truth_gradient(left, right, interpolation);
self.vertex_gradient(ui, "Ground Truth (CPU gradient) - vertices", bg_fill, &g);
self.tex_gradient(ui, "Ground Truth (CPU gradient) - texture", bg_fill, &g);
} else {
let g = Gradient::ground_truth_gradient(left, right, interpolation)
.with_bg_fill(bg_fill);
self.vertex_gradient(
ui,
"Ground Truth (CPU gradient, CPU blending) - vertices",
bg_fill,
&g,
);
self.tex_gradient(
ui,
"Ground Truth (CPU gradient, CPU blending) - texture",
bg_fill,
&g,
);
let g = Gradient::ground_truth_gradient(left, right, interpolation);
self.vertex_gradient(ui, "CPU gradient, GPU blending - vertices", bg_fill, &g);
self.tex_gradient(ui, "CPU gradient, GPU blending - texture", bg_fill, &g);
}
let g = Gradient::endpoints(left, right);
match interpolation {
Interpolation::Linear => {
// texture sampler is sRGBA aware, and should therefore be linear
self.tex_gradient(ui, "Texture of width 2 (test texture sampler)", bg_fill, &g);
}
Interpolation::Gamma => {
// vertex shader uses gamma
self.vertex_gradient(
ui,
"Triangle mesh of width 2 (test vertex decode and interpolation)",
bg_fill,
&g,
);
}
}
});
}
fn tex_gradient(&mut self, ui: &mut Ui, label: &str, bg_fill: Color32, gradient: &Gradient) {
if !self.texture_gradients {
return;
}
ui.horizontal(|ui| {
let tex = self.tex_mngr.get(ui.ctx(), gradient);
let texel_offset = 0.5 / (gradient.0.len() as f32);
let uv = Rect::from_min_max(pos2(texel_offset, 0.0), pos2(1.0 - texel_offset, 1.0));
ui.add(Image::new(tex, GRADIENT_SIZE).bg_fill(bg_fill).uv(uv))
.on_hover_text(format!(
"A texture that is {} texels wide",
gradient.0.len()
));
ui.label(label);
});
}
fn vertex_gradient(&mut self, ui: &mut Ui, label: &str, bg_fill: Color32, gradient: &Gradient) {
if !self.vertex_gradients {
return;
}
ui.horizontal(|ui| {
vertex_gradient(ui, bg_fill, gradient).on_hover_text(format!(
"A triangle mesh that is {} vertices wide",
gradient.0.len()
));
ui.label(label);
});
}
}
fn vertex_gradient(ui: &mut Ui, bg_fill: Color32, gradient: &Gradient) -> Response {
use egui::epaint::*;
let (rect, response) = ui.allocate_at_least(GRADIENT_SIZE, Sense::hover());
if bg_fill != Default::default() {
let mut mesh = Mesh::default();
mesh.add_colored_rect(rect, bg_fill);
ui.painter().add(Shape::mesh(mesh));
}
{
let n = gradient.0.len();
assert!(n >= 2);
let mut mesh = Mesh::default();
for (i, &color) in gradient.0.iter().enumerate() {
let t = i as f32 / (n as f32 - 1.0);
let x = lerp(rect.x_range(), t);
mesh.colored_vertex(pos2(x, rect.top()), color);
mesh.colored_vertex(pos2(x, rect.bottom()), color);
if i < n - 1 {
let i = i as u32;
mesh.add_triangle(2 * i, 2 * i + 1, 2 * i + 2);
mesh.add_triangle(2 * i + 1, 2 * i + 2, 2 * i + 3);
}
}
ui.painter().add(Shape::mesh(mesh));
}
response
}
#[derive(Clone, Copy)]
enum Interpolation {
Linear,
Gamma,
}
#[derive(Clone, Hash, PartialEq, Eq)]
struct Gradient(pub Vec<Color32>);
impl Gradient {
pub fn one_color(srgba: Color32) -> Self {
Self(vec![srgba, srgba])
}
pub fn endpoints(left: Color32, right: Color32) -> Self {
Self(vec![left, right])
}
pub fn ground_truth_gradient(
left: Color32,
right: Color32,
interpolation: Interpolation,
) -> Self {
match interpolation {
Interpolation::Linear => Self::ground_truth_linear_gradient(left, right),
Interpolation::Gamma => Self::ground_truth_gamma_gradient(left, right),
}
}
pub fn ground_truth_linear_gradient(left: Color32, right: Color32) -> Self {
let left = Rgba::from(left);
let right = Rgba::from(right);
let n = 255;
Self(
(0..=n)
.map(|i| {
let t = i as f32 / n as f32;
Color32::from(lerp(left..=right, t))
})
.collect(),
)
}
pub fn ground_truth_gamma_gradient(left: Color32, right: Color32) -> Self {
let n = 255;
Self(
(0..=n)
.map(|i| {
let t = i as f32 / n as f32;
lerp_color_gamma(left, right, t)
})
.collect(),
)
}
/// Do premultiplied alpha-aware blending of the gradient on top of the fill color
/// in gamma-space.
pub fn with_bg_fill(self, bg: Color32) -> Self {
Self(
self.0
.into_iter()
.map(|fg| {
let a = fg.a() as f32 / 255.0;
Color32::from_rgba_premultiplied(
(bg[0] as f32 * (1.0 - a) + fg[0] as f32).round() as u8,
(bg[1] as f32 * (1.0 - a) + fg[1] as f32).round() as u8,
(bg[2] as f32 * (1.0 - a) + fg[2] as f32).round() as u8,
(bg[3] as f32 * (1.0 - a) + fg[3] as f32).round() as u8,
)
})
.collect(),
)
}
pub fn to_pixel_row(&self) -> Vec<Color32> {
self.0.clone()
}
}
#[derive(Default)]
struct TextureManager(HashMap<Gradient, TextureHandle>);
impl TextureManager {
fn get(&mut self, ctx: &egui::Context, gradient: &Gradient) -> &TextureHandle {
self.0.entry(gradient.clone()).or_insert_with(|| {
let pixels = gradient.to_pixel_row();
let width = pixels.len();
let height = 1;
ctx.load_texture(
"color_test_gradient",
epaint::ColorImage {
size: [width, height],
pixels,
},
TextureOptions::LINEAR,
)
})
}
}
fn pixel_test(ui: &mut Ui) {
ui.label("Each subsequent square should be one physical pixel larger than the previous. They should be exactly one physical pixel apart. They should be perfectly aligned to the pixel grid.");
let color = if ui.style().visuals.dark_mode {
egui::Color32::WHITE
} else {
egui::Color32::BLACK
};
let pixels_per_point = ui.ctx().pixels_per_point();
let num_squares: u32 = 8;
let size_pixels = vec2(
((num_squares + 1) * (num_squares + 2) / 2) as f32,
num_squares as f32,
);
let size_points = size_pixels / pixels_per_point + Vec2::splat(2.0);
let (response, painter) = ui.allocate_painter(size_points, Sense::hover());
let mut cursor_pixel = Pos2::new(
response.rect.min.x * pixels_per_point,
response.rect.min.y * pixels_per_point,
)
.ceil();
for size in 1..=num_squares {
let rect_points = Rect::from_min_size(
Pos2::new(
cursor_pixel.x / pixels_per_point,
cursor_pixel.y / pixels_per_point,
),
Vec2::splat(size as f32) / pixels_per_point,
);
painter.rect_filled(rect_points, 0.0, color);
cursor_pixel.x += (1 + size) as f32;
}
}
fn blending_and_feathering_test(ui: &mut Ui) {
let size = vec2(512.0, 512.0);
let (response, painter) = ui.allocate_painter(size, Sense::hover());
let rect = response.rect;
let mut top_half = rect;
top_half.set_bottom(top_half.center().y);
painter.rect_filled(top_half, 0.0, Color32::BLACK);
paint_fine_lines_and_text(&painter, top_half, Color32::WHITE);
let mut bottom_half = rect;
bottom_half.set_top(bottom_half.center().y);
painter.rect_filled(bottom_half, 0.0, Color32::WHITE);
paint_fine_lines_and_text(&painter, bottom_half, Color32::BLACK);
}
fn text_on_bg(ui: &mut egui::Ui, fg: Color32, bg: Color32) {
assert!(fg.is_opaque());
assert!(bg.is_opaque());
ui.horizontal(|ui| {
ui.label(
RichText::from("▣ The quick brown fox jumps over the lazy dog and runs away.")
.background_color(bg)
.color(fg),
);
ui.label(format!(
"({} {} {}) on ({} {} {})",
fg.r(),
fg.g(),
fg.b(),
bg.r(),
bg.g(),
bg.b(),
));
});
}
fn paint_fine_lines_and_text(painter: &egui::Painter, mut rect: Rect, color: Color32) {
{
let mut y = 0.0;
for opacity in [1.00, 0.50, 0.25, 0.10, 0.05, 0.02, 0.01, 0.00] {
painter.text(
rect.center_top() + vec2(0.0, y),
Align2::LEFT_TOP,
format!("{:.0}% white", 100.0 * opacity),
FontId::proportional(14.0),
Color32::WHITE.linear_multiply(opacity),
);
painter.text(
rect.center_top() + vec2(80.0, y),
Align2::LEFT_TOP,
format!("{:.0}% gray", 100.0 * opacity),
FontId::proportional(14.0),
Color32::GRAY.linear_multiply(opacity),
);
painter.text(
rect.center_top() + vec2(160.0, y),
Align2::LEFT_TOP,
format!("{:.0}% black", 100.0 * opacity),
FontId::proportional(14.0),
Color32::BLACK.linear_multiply(opacity),
);
y += 20.0;
}
for font_size in [6.0, 7.0, 8.0, 9.0, 10.0, 12.0, 14.0] {
painter.text(
rect.center_top() + vec2(0.0, y),
Align2::LEFT_TOP,
format!(
"{font_size}px - The quick brown fox jumps over the lazy dog and runs away."
),
FontId::proportional(font_size),
color,
);
y += font_size + 1.0;
}
}
rect.max.x = rect.center().x;
rect = rect.shrink(12.0);
for width in [0.5, 1.0, 2.0] {
painter.text(
rect.left_top(),
Align2::CENTER_CENTER,
width.to_string(),
FontId::monospace(12.0),
color,
);
painter.add(egui::epaint::CubicBezierShape::from_points_stroke(
[
rect.left_top() + vec2(16.0, 0.0),
rect.right_top(),
rect.right_center(),
rect.right_bottom(),
],
false,
Color32::TRANSPARENT,
Stroke::new(width, color),
));
rect.min.y += 32.0;
rect.max.x -= 32.0;
}
rect.min.y += 16.0;
painter.text(
rect.left_top(),
Align2::LEFT_CENTER,
"transparent --> opaque",
FontId::monospace(10.0),
color,
);
rect.min.y += 12.0;
let mut mesh = Mesh::default();
mesh.colored_vertex(rect.left_bottom(), Color32::TRANSPARENT);
mesh.colored_vertex(rect.left_top(), Color32::TRANSPARENT);
mesh.colored_vertex(rect.right_bottom(), color);
mesh.colored_vertex(rect.right_top(), color);
mesh.add_triangle(0, 1, 2);
mesh.add_triangle(1, 2, 3);
painter.add(mesh);
}
fn mul_color_gamma(left: Color32, right: Color32) -> Color32 {
Color32::from_rgba_premultiplied(
(left.r() as f32 * right.r() as f32 / 255.0).round() as u8,
(left.g() as f32 * right.g() as f32 / 255.0).round() as u8,
(left.b() as f32 * right.b() as f32 / 255.0).round() as u8,
(left.a() as f32 * right.a() as f32 / 255.0).round() as u8,
)
}
fn lerp_color_gamma(left: Color32, right: Color32, t: f32) -> Color32 {
Color32::from_rgba_premultiplied(
lerp((left[0] as f32)..=(right[0] as f32), t).round() as u8,
lerp((left[1] as f32)..=(right[1] as f32), t).round() as u8,
lerp((left[2] as f32)..=(right[2] as f32), t).round() as u8,
lerp((left[3] as f32)..=(right[3] as f32), t).round() as u8,
)
}