egui/emigui/src/mesher.rs
2020-04-24 18:47:14 +02:00

549 lines
17 KiB
Rust

#![allow(clippy::identity_op)]
/// Outputs render info in a format suitable for e.g. OpenGL.
use crate::{
color::{srgba, Color},
fonts::Fonts,
math::*,
types::PaintCmd,
Outline,
};
const WHITE_UV: (u16, u16) = (1, 1);
#[derive(Clone, Copy, Debug, Default, Serialize)]
pub struct Vertex {
/// Pixel coordinates
pub pos: Pos2,
/// Texel indices into the texture
pub uv: (u16, u16),
/// sRGBA
pub color: Color,
}
#[derive(Clone, Debug, Default, Serialize)]
pub struct Mesh {
/// Draw as triangles (i.e. the length is a multiple of three)
pub indices: Vec<u32>,
pub vertices: Vec<Vertex>,
}
/// Grouped by clip rectangles, in pixel coordinates
pub type PaintBatches = Vec<(Rect, Mesh)>;
// ----------------------------------------------------------------------------
impl Mesh {
pub fn append(&mut self, mesh: &Mesh) {
let index_offset = self.vertices.len() as u32;
for index in &mesh.indices {
self.indices.push(index_offset + index);
}
self.vertices.extend(mesh.vertices.iter());
}
fn triangle(&mut self, a: u32, b: u32, c: u32) {
self.indices.push(a);
self.indices.push(b);
self.indices.push(c);
}
/// Uniformly colored rectangle
pub fn add_rect(&mut self, top_left: Vertex, bottom_right: Vertex) {
debug_assert_eq!(top_left.color, bottom_right.color);
let idx = self.vertices.len() as u32;
self.triangle(idx + 0, idx + 1, idx + 2);
self.triangle(idx + 2, idx + 1, idx + 3);
let top_right = Vertex {
pos: pos2(bottom_right.pos.x, top_left.pos.y),
uv: (bottom_right.uv.0, top_left.uv.1),
color: top_left.color,
};
let botom_left = Vertex {
pos: pos2(top_left.pos.x, bottom_right.pos.y),
uv: (top_left.uv.0, bottom_right.uv.1),
color: top_left.color,
};
self.vertices.push(top_left);
self.vertices.push(top_right);
self.vertices.push(botom_left);
self.vertices.push(bottom_right);
}
/// Split a large mesh into many small.
/// All the returned meshes will have indices that fit into u16.
pub fn split_to_u16(self) -> Vec<Mesh> {
const MAX_SIZE: u32 = 1 << 16;
if self.vertices.len() < MAX_SIZE as usize {
return vec![self]; // Common-case optimization
}
let mut output = vec![];
let mut index_cursor = 0;
while index_cursor < self.indices.len() {
let span_start = index_cursor;
let mut min_vindex = self.indices[index_cursor];
let mut max_vindex = self.indices[index_cursor];
while index_cursor < self.indices.len() {
let (mut new_min, mut new_max) = (min_vindex, max_vindex);
for i in 0..3 {
let idx = self.indices[index_cursor + i];
new_min = new_min.min(idx);
new_max = new_max.max(idx);
}
if new_max - new_min < MAX_SIZE {
// Triangle fits
min_vindex = new_min;
max_vindex = new_max;
index_cursor += 3;
} else {
break;
}
}
assert!(
index_cursor > span_start,
"One triangle spanned more than {} vertices",
MAX_SIZE
);
output.push(Mesh {
indices: self.indices[span_start..index_cursor]
.iter()
.map(|vi| vi - min_vindex)
.collect(),
vertices: self.vertices[(min_vindex as usize)..=(max_vindex as usize)].to_vec(),
});
}
output
}
}
// ----------------------------------------------------------------------------
#[derive(Clone, Debug, Default)]
pub struct PathPoint {
pos: Pos2,
/// For filled paths the normal is used for antialiasing.
/// For outlines the normal is used for figuring out how to make the line wide
/// (i.e. in what direction to expand).
/// The normal could be estimated by differences between successive points,
/// but that would be less accurate (and in some cases slower).
normal: Vec2,
}
#[derive(Clone, Debug, Default)]
pub struct Path(Vec<PathPoint>);
impl Path {
pub fn clear(&mut self) {
self.0.clear();
}
pub fn add_point(&mut self, pos: Pos2, normal: Vec2) {
self.0.push(PathPoint { pos, normal });
}
pub fn add_circle(&mut self, center: Pos2, radius: f32) {
let n = 32; // TODO: parameter
for i in 0..n {
let angle = remap(i as f32, 0.0, n as f32, 0.0, TAU);
let normal = vec2(angle.cos(), angle.sin());
self.add_point(center + radius * normal, normal);
}
}
pub fn add_line(&mut self, points: &[Pos2]) {
let n = points.len();
assert!(n >= 2);
self.add_point(points[0], (points[1] - points[0]).normalized().rot90());
for i in 1..n - 1 {
let n0 = (points[i] - points[i - 1]).normalized().rot90();
let n1 = (points[i + 1] - points[i]).normalized().rot90();
let v = (n0 + n1) / 2.0;
let normal = v / v.length_sq();
self.add_point(points[i], normal); // TODO: handle VERY sharp turns better
}
self.add_point(
points[n - 1],
(points[n - 1] - points[n - 2]).normalized().rot90(),
);
}
pub fn add_rectangle(&mut self, rect: &Rect) {
let min = rect.min();
let max = rect.max();
self.add_point(pos2(min.x, min.y), vec2(-1.0, -1.0));
self.add_point(pos2(max.x, min.y), vec2(1.0, -1.0));
self.add_point(pos2(max.x, max.y), vec2(1.0, 1.0));
self.add_point(pos2(min.x, max.y), vec2(-1.0, 1.0));
}
pub fn add_rounded_rectangle(&mut self, rect: &Rect, corner_radius: f32) {
let min = rect.min();
let max = rect.max();
let cr = corner_radius
.min(rect.width() * 0.5)
.min(rect.height() * 0.5);
if cr <= 0.0 {
self.add_rectangle(rect);
} else {
self.add_circle_quadrant(pos2(max.x - cr, max.y - cr), cr, 0.0);
self.add_circle_quadrant(pos2(min.x + cr, max.y - cr), cr, 1.0);
self.add_circle_quadrant(pos2(min.x + cr, min.y + cr), cr, 2.0);
self.add_circle_quadrant(pos2(max.x - cr, min.y + cr), cr, 3.0);
}
}
/// with x right, and y down (GUI coords) we have:
/// angle = dir
/// 0 * TAU / 4 = right
/// quadrant 0, right down
/// 1 * TAU / 4 = down
/// quadrant 1, down left
/// 2 * TAU / 4 = left
/// quadrant 2 left up
/// 3 * TAU / 4 = up
/// quadrant 3 up rigth
/// 4 * TAU / 4 = right
pub fn add_circle_quadrant(&mut self, center: Pos2, radius: f32, quadrant: f32) {
let n = 8;
const RIGHT_ANGLE: f32 = TAU / 4.0;
for i in 0..=n {
let angle = remap(
i as f32,
0.0,
n as f32,
quadrant * RIGHT_ANGLE,
(quadrant + 1.0) * RIGHT_ANGLE,
);
let normal = vec2(angle.cos(), angle.sin());
self.add_point(center + radius * normal, normal);
}
}
}
// ----------------------------------------------------------------------------
#[derive(Clone, Copy, PartialEq)]
pub enum PathType {
Open,
Closed,
}
use self::PathType::*;
pub struct MesherOptions {
pub anti_alias: bool,
pub aa_size: f32,
pub debug_paint_clip_rects: bool,
}
impl Default for MesherOptions {
fn default() -> Self {
Self {
anti_alias: true,
aa_size: 1.0,
debug_paint_clip_rects: false,
}
}
}
pub fn fill_closed_path(
mesh: &mut Mesh,
options: &MesherOptions,
path: &[PathPoint],
color: Color,
) {
let n = path.len() as u32;
let vert = |pos, color| Vertex {
pos,
uv: WHITE_UV,
color,
};
if options.anti_alias {
let color_outer = color.transparent();
let idx_inner = mesh.vertices.len() as u32;
let idx_outer = idx_inner + 1;
for i in 2..n {
mesh.triangle(idx_inner + 2 * (i - 1), idx_inner, idx_inner + 2 * i);
}
let mut i0 = n - 1;
for i1 in 0..n {
let p1 = &path[i1 as usize];
let dm = p1.normal * options.aa_size * 0.5;
mesh.vertices.push(vert(p1.pos - dm, color));
mesh.vertices.push(vert(p1.pos + dm, color_outer));
mesh.triangle(idx_inner + i1 * 2, idx_inner + i0 * 2, idx_outer + 2 * i0);
mesh.triangle(idx_outer + i0 * 2, idx_outer + i1 * 2, idx_inner + 2 * i1);
i0 = i1;
}
} else {
let idx = mesh.vertices.len() as u32;
mesh.vertices
.extend(path.iter().map(|p| vert(p.pos, color)));
for i in 2..n {
mesh.triangle(idx, idx + i - 1, idx + i);
}
}
}
pub fn paint_path(
mesh: &mut Mesh,
options: &MesherOptions,
path_type: PathType,
path: &[PathPoint],
color: Color,
width: f32,
) {
let n = path.len() as u32;
let hw = width / 2.0;
let idx = mesh.vertices.len() as u32;
let vert = |pos, color| Vertex {
pos,
uv: WHITE_UV,
color,
};
if options.anti_alias {
let color_outer = color.transparent();
let thin_line = width <= 1.0;
let mut color_inner = color;
if thin_line {
// Fade out as it gets thinner:
color_inner.a = (f32::from(color_inner.a) * width).round() as u8;
}
// TODO: line caps ?
let mut i0 = n - 1;
for i1 in 0..n {
let connect_with_previous = path_type == PathType::Closed || i1 > 0;
if thin_line {
let p1 = &path[i1 as usize];
let p = p1.pos;
let n = p1.normal;
mesh.vertices
.push(vert(p + n * options.aa_size, color_outer));
mesh.vertices.push(vert(p, color_inner));
mesh.vertices
.push(vert(p - n * options.aa_size, color_outer));
if connect_with_previous {
mesh.triangle(idx + 3 * i0 + 0, idx + 3 * i0 + 1, idx + 3 * i1 + 0);
mesh.triangle(idx + 3 * i0 + 1, idx + 3 * i1 + 0, idx + 3 * i1 + 1);
mesh.triangle(idx + 3 * i0 + 1, idx + 3 * i0 + 2, idx + 3 * i1 + 1);
mesh.triangle(idx + 3 * i0 + 2, idx + 3 * i1 + 1, idx + 3 * i1 + 2);
}
} else {
let hw = (width - options.aa_size) * 0.5;
let p1 = &path[i1 as usize];
let p = p1.pos;
let n = p1.normal;
mesh.vertices
.push(vert(p + n * (hw + options.aa_size), color_outer));
mesh.vertices.push(vert(p + n * (hw + 0.0), color_inner));
mesh.vertices.push(vert(p - n * (hw + 0.0), color_inner));
mesh.vertices
.push(vert(p - n * (hw + options.aa_size), color_outer));
if connect_with_previous {
mesh.triangle(idx + 4 * i0 + 0, idx + 4 * i0 + 1, idx + 4 * i1 + 0);
mesh.triangle(idx + 4 * i0 + 1, idx + 4 * i1 + 0, idx + 4 * i1 + 1);
mesh.triangle(idx + 4 * i0 + 1, idx + 4 * i0 + 2, idx + 4 * i1 + 1);
mesh.triangle(idx + 4 * i0 + 2, idx + 4 * i1 + 1, idx + 4 * i1 + 2);
mesh.triangle(idx + 4 * i0 + 2, idx + 4 * i0 + 3, idx + 4 * i1 + 2);
mesh.triangle(idx + 4 * i0 + 3, idx + 4 * i1 + 2, idx + 4 * i1 + 3);
}
}
i0 = i1;
}
} else {
let last_index = if path_type == Closed { n } else { n - 1 };
for i in 0..last_index {
mesh.triangle(
idx + (2 * i + 0) % (2 * n),
idx + (2 * i + 1) % (2 * n),
idx + (2 * i + 2) % (2 * n),
);
mesh.triangle(
idx + (2 * i + 2) % (2 * n),
idx + (2 * i + 1) % (2 * n),
idx + (2 * i + 3) % (2 * n),
);
}
for p in path {
mesh.vertices.push(vert(p.pos + hw * p.normal, color));
mesh.vertices.push(vert(p.pos - hw * p.normal, color));
}
}
}
// ----------------------------------------------------------------------------
pub fn mesh_command(
options: &MesherOptions,
fonts: &Fonts,
command: PaintCmd,
out_mesh: &mut Mesh,
) {
match command {
PaintCmd::Circle {
center,
fill_color,
outline,
radius,
} => {
let mut path = Path::default();
path.add_circle(center, radius);
if let Some(color) = fill_color {
fill_closed_path(out_mesh, options, &path.0, color);
}
if let Some(outline) = outline {
paint_path(
out_mesh,
options,
Closed,
&path.0,
outline.color,
outline.width,
);
}
}
PaintCmd::Mesh(mesh) => {
out_mesh.append(&mesh);
}
PaintCmd::Line {
points,
color,
width,
} => {
let n = points.len();
if n >= 2 {
let mut path = Path::default();
path.add_line(&points);
paint_path(out_mesh, options, Open, &path.0, color, width);
}
}
PaintCmd::Path {
path,
closed,
fill_color,
outline,
} => {
if let Some(fill_color) = fill_color {
debug_assert!(
closed,
"You asked to fill a path that is not closed. That makes no sense."
);
fill_closed_path(out_mesh, options, &path.0, fill_color);
}
if let Some(outline) = outline {
let typ = if closed { Closed } else { Open };
paint_path(
out_mesh,
options,
typ,
&path.0,
outline.color,
outline.width,
);
}
}
PaintCmd::Rect {
corner_radius,
fill_color,
outline,
rect,
} => {
let mut path = Path::default();
path.add_rounded_rectangle(&rect, corner_radius);
if let Some(fill_color) = fill_color {
fill_closed_path(out_mesh, options, &path.0, fill_color);
}
if let Some(outline) = outline {
paint_path(
out_mesh,
options,
Closed,
&path.0,
outline.color,
outline.width,
);
}
}
PaintCmd::Text {
color,
pos,
text,
text_style,
x_offsets,
} => {
let font = &fonts[text_style];
for (c, x_offset) in text.chars().zip(x_offsets.iter()) {
if let Some(glyph) = font.uv_rect(c) {
let mut top_left = Vertex {
pos: pos + glyph.offset + vec2(*x_offset, 0.0),
uv: glyph.min,
color,
};
top_left.pos.x = font.round_to_pixel(top_left.pos.x); // Pixel-perfection.
top_left.pos.y = font.round_to_pixel(top_left.pos.y); // Pixel-perfection.
let bottom_right = Vertex {
pos: top_left.pos + glyph.size,
uv: glyph.max,
color,
};
out_mesh.add_rect(top_left, bottom_right);
}
}
}
}
}
pub fn mesh_paint_commands(
options: &MesherOptions,
fonts: &Fonts,
commands: Vec<(Rect, PaintCmd)>,
) -> Vec<(Rect, Mesh)> {
let mut batches = PaintBatches::default();
for (clip_rect, cmd) in commands {
// TODO: cull(clip_rect, cmd)
if batches.is_empty() || batches.last().unwrap().0 != clip_rect {
batches.push((clip_rect, Mesh::default()));
if options.debug_paint_clip_rects && !clip_rect.is_empty() {
let out_mesh = &mut batches.last_mut().unwrap().1;
mesh_command(
options,
fonts,
PaintCmd::Rect {
rect: clip_rect,
corner_radius: 0.0,
fill_color: Some(srgba(50, 100, 200, 64)),
outline: Some(Outline::new(1.0, srgba(200, 200, 200, 255))),
},
out_mesh,
)
}
}
let out_mesh = &mut batches.last_mut().unwrap().1;
mesh_command(options, fonts, cmd, out_mesh);
}
batches
}