92 lines
2.7 KiB
Rust
92 lines
2.7 KiB
Rust
// pathfinder/area-lut/src/main.rs
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extern crate clap;
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extern crate euclid;
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extern crate image;
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use clap::{App, Arg};
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use euclid::default::Point2D;
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use image::{ImageBuffer, Luma};
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use std::f32;
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use std::path::Path;
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const WIDTH: u32 = 256;
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const HEIGHT: u32 = 256;
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fn solve_line_y(p0: &Point2D<f32>, p1: &Point2D<f32>, y: f32) -> Point2D<f32> {
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let m = (p1.y - p0.y) / (p1.x - p0.x);
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Point2D::new(p0.x - (p0.y - y) / m, y)
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}
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fn area_tri(p0: Point2D<f32>, p1: Point2D<f32>) -> f32 {
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0.5 * (p1.x - p0.x) * (p0.y - p1.y)
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}
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fn area_rect(p0: Point2D<f32>, p1: Point2D<f32>) -> f32 {
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(p1.x - p0.x) * (p0.y - p1.y)
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}
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fn main() {
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let app = App::new("Pathfinder Area LUT Generator")
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.version("0.1")
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.author("The Pathfinder Project Developers")
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.about("Generates area lookup tables for use with Pathfinder")
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.arg(Arg::with_name("OUTPUT-PATH").help("The `.png` image to produce")
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.required(true)
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.index(1));
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let matches = app.get_matches();
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let image = ImageBuffer::from_fn(WIDTH, HEIGHT, |u, v| {
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if u == 0 {
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return Luma([255])
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}
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if u == WIDTH - 1 {
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return Luma([0])
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}
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let y = ((u as f32) - (WIDTH / 2) as f32) / 16.0;
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let dydx = -(v as f32) / 16.0;
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let (x_left, x_right) = (-0.5, 0.5);
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let (y_left, y_right) = (dydx * x_left + y, dydx * x_right + y);
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let (p0, p1) = (Point2D::new(x_left, y_left), Point2D::new(x_right, y_right));
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let p2 = solve_line_y(&p0, &p1, -0.5);
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let p3 = Point2D::new(p1.x, -0.5);
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let p4 = solve_line_y(&p0, &p1, 0.5);
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let p7 = Point2D::new(p1.x, 0.5);
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let alpha;
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if p0.y > 0.5 {
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if p1.y < -0.5 {
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// Case 0
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alpha = area_tri(p0, p1) - area_tri(p2, p1) - area_rect(p0, p7) + area_tri(p0, p4);
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} else if p1.y < 0.5 {
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// Case 6
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alpha = area_tri(p0, p1) - area_rect(p0, p7) + area_tri(p0, p4);
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} else {
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// Case 3
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alpha = 0.0;
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}
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} else if p0.y > -0.5 {
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if p1.y < -0.5 {
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// Case 1
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alpha = area_tri(p0, p1) - area_tri(p2, p1) - area_rect(p0, p7);
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} else {
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// Case 4
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alpha = area_tri(p0, p1) - area_rect(p0, p7);
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}
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} else {
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// Case 2
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alpha = -area_rect(p0, p7) + area_rect(p0, p3);
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}
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Luma([f32::round(alpha * 255.0) as u8])
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});
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let output_path = matches.value_of("OUTPUT-PATH").unwrap();
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let output_path = Path::new(output_path);
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image.save(&output_path).unwrap();
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}
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