use super::CodePiece;
use crate::impl_code_piece;
use glsl::syntax::ShaderStage;
use glsl::syntax::TranslationUnit;
use glsl::transpiler::glsl::show_translation_unit;
use glsl_quasiquote::glsl;

pub struct Mercator(pub ShaderStage);

impl Mercator {
    pub fn new() -> Self {
        let raw = glsl! {

            uniform float R;

            vec2 mercatorProject(vec2 loc) {
                // 将经纬度从度转换为弧度
                float lonRad = radians(loc.x);
                float latRad = radians(loc.y);

                // X轴投影 (线性映射经度)
                float x = R * lonRad;

                // Y轴投影 (非线性映射纬度)
                float y = R * log(tan(latRad / 2.0 + radians(45.0)));

                return vec2(x, y);
            }

            vec2 mercatorInverse(vec2 loc) {
                // 计算经度 (lon)，线性反映射
                float lon = degrees(loc.x / R);  // 将弧度转换为度数

                // 计算纬度 (lat)，非线性反映射
                float lat = degrees(2.0 * atan(exp(loc.y / R)) - radians(90.0));

                return vec2(lon, lat);  // 返回经纬度 (lon, lat)
            }
        };

        Self(raw)
    }
}

impl_code_piece!(Mercator, 0);