sao-ui-rs/src/draw.rs

use crate::abi::UiPanel;
use crate::{Color, Vec2};

pub struct DrawContext {
    panel: UiPanel,
    offset: Vec2,
}

impl DrawContext {
    pub fn new(panel: UiPanel) -> Self {
        Self {
            panel,
            offset: Vec2::ZERO,
        }
    }

    pub fn draw_triangle(&self, v1: Vec2, v2: Vec2, v3: Vec2, color: Color) {
        let v1 = v1 + self.offset;
        let v2 = v2 + self.offset;
        let v3 = v3 + self.offset;
        self.panel.draw_triangle(v1, v2, v3, color);
    }

    pub fn draw_circle(&self, center: Vec2, radius: f32, color: Color) {
        use std::f32::consts::PI;

        let delta = PI / 16.0;
        let limit = PI * 2.0 + delta;

        let mut last_spoke = Vec2::new(radius + center.x, center.y);
        let mut theta = delta;
        while theta < limit {
            let new_spoke = Vec2::from_angle(theta) * radius + center;
            self.draw_triangle(center, last_spoke, new_spoke, color);
            last_spoke = new_spoke;
            theta += delta;
        }
    }

    pub fn draw_ring(&self, center: Vec2, radius: f32, thickness: f32, color: Color) {
        use std::f32::consts::PI;

        let delta = PI / 64.0;
        let limit = PI * 2.0 + delta;

        let mut last_spoke = glam::Vec2::new(radius + center.x, center.y);
        let mut last_theta = 0.0;
        let mut theta = delta;
        while theta < limit {
            let angle = Vec2::from_angle(theta);
            let new_spoke = angle * radius + center;
            let new_spoke2 = angle * (radius + thickness) + center;
            let last_spoke2 = Vec2::from_angle(last_theta) * (radius + thickness) + center;

            self.draw_triangle(new_spoke2, last_spoke, new_spoke, color);
            self.draw_triangle(new_spoke2, last_spoke2, last_spoke, color);

            last_spoke = new_spoke;
            last_theta = theta;
            theta += delta;
        }
    }

    pub fn draw_rect(&self, xy: &Vec2, size: &Vec2, color: Color) {
        let v1 = *xy;
        let v2 = v1 + Vec2::new(size.x, 0.0);
        let v3 = v1 + Vec2::new(0.0, size.y);
        let v4 = v1 + *size;

        self.draw_triangle(v1, v2, v3, color);
        self.draw_triangle(v2, v3, v4, color);
    }

    pub fn with_offset(&self, offset: Vec2) -> Self {
        Self {
            panel: self.panel,
            offset: self.offset + offset,
        }
    }
}