re_viewer 0.2.0-alpha.3

use glam::{Vec2, Vec4};

/// Converts float from 0.0..=1.0 into a color using Turbo.
///
/// The Turbo color map described [here](https://ai.googleblog.com/2019/08/turbo-improved-rainbow-colormap-for.html)
///
/// Turbo color map is originally a lookup table!
/// I.e. for any value not captured we'd need to interpolate.
///
/// Instead, we use this polynomial approximation.
/// [see here](https://gist.github.com/mikhailov-work/0d177465a8151eb6ede1768d51d476c7)
#[allow(clippy::excessive_precision)]
pub fn turbo_color_map(x: f32) -> egui::Color32 {
    const RED_VEC4: Vec4 = Vec4::new(0.13572138, 4.61539260, -42.66032258, 132.13108234);
    const GREEN_VEC4: Vec4 = Vec4::new(0.09140261, 2.19418839, 4.84296658, -14.18503333);
    const BLUE_VEC4: Vec4 = Vec4::new(0.10667330, 12.64194608, -60.58204836, 110.36276771);
    const RED_VEC2: Vec2 = Vec2::new(-152.94239396, 59.28637943);
    const GREEN_VEC2: Vec2 = Vec2::new(4.27729857, 2.82956604);
    const BLURE_VEC2: Vec2 = Vec2::new(-89.90310912, 27.34824973);

    let v4 = glam::vec4(1.0, x, x * x, x * x * x);
    let v2 = glam::vec2(v4.z, v4.w) * v4.z;

    // Above sources are not explicit about it but this color is seemingly already in sRGB gamma space.
    egui::Color32::from_rgb(
        ((v4.dot(RED_VEC4) + v2.dot(RED_VEC2)) * 255.0) as u8,
        ((v4.dot(GREEN_VEC4) + v2.dot(GREEN_VEC2)) * 255.0) as u8,
        ((v4.dot(BLUE_VEC4) + v2.dot(BLURE_VEC2)) * 255.0) as u8,
    )
}

/// LUT as defined [here](https://github.com/sjmgarnier/viridisLite/blob/ffc7061/R/zzz.R)
///
/// Converted to bytes using this python snippet:
/// ```python
/// for (r, g, b, asdf) in zip(R, G, B, opt):
//      if asdf == 'D':
//          print("[{}, {}, {}],".format(int(r * 255.0 + 0.5), int(g * 255.0 + 0.5), int(b * 255.0 + 0.5)))
/// ```
const VIRIDIS_SRGB_BYTES: [[u8; 3]; 256] = [
    [68, 1, 84],
    [68, 2, 86],
    [69, 4, 87],
    [69, 5, 89],
    [70, 7, 90],
    [70, 8, 92],
    [70, 10, 93],
    [70, 11, 94],
    [71, 13, 96],
    [71, 14, 97],
    [71, 16, 99],
    [71, 17, 100],
    [71, 19, 101],
    [72, 20, 103],
    [72, 22, 104],
    [72, 23, 105],
    [72, 24, 106],
    [72, 26, 108],
    [72, 27, 109],
    [72, 28, 110],
    [72, 29, 111],
    [72, 31, 112],
    [72, 32, 113],
    [72, 33, 115],
    [72, 35, 116],
    [72, 36, 117],
    [72, 37, 118],
    [72, 38, 119],
    [72, 40, 120],
    [72, 41, 121],
    [71, 42, 122],
    [71, 44, 122],
    [71, 45, 123],
    [71, 46, 124],
    [71, 47, 125],
    [70, 48, 126],
    [70, 50, 126],
    [70, 51, 127],
    [70, 52, 128],
    [69, 53, 129],
    [69, 55, 129],
    [69, 56, 130],
    [68, 57, 131],
    [68, 58, 131],
    [68, 59, 132],
    [67, 61, 132],
    [67, 62, 133],
    [66, 63, 133],
    [66, 64, 134],
    [66, 65, 134],
    [65, 66, 135],
    [65, 68, 135],
    [64, 69, 136],
    [64, 70, 136],
    [63, 71, 136],
    [63, 72, 137],
    [62, 73, 137],
    [62, 74, 137],
    [62, 76, 138],
    [61, 77, 138],
    [61, 78, 138],
    [60, 79, 138],
    [60, 80, 139],
    [59, 81, 139],
    [59, 82, 139],
    [58, 83, 139],
    [58, 84, 140],
    [57, 85, 140],
    [57, 86, 140],
    [56, 88, 140],
    [56, 89, 140],
    [55, 90, 140],
    [55, 91, 141],
    [54, 92, 141],
    [54, 93, 141],
    [53, 94, 141],
    [53, 95, 141],
    [52, 96, 141],
    [52, 97, 141],
    [51, 98, 141],
    [51, 99, 141],
    [50, 100, 142],
    [50, 101, 142],
    [49, 102, 142],
    [49, 103, 142],
    [49, 104, 142],
    [48, 105, 142],
    [48, 106, 142],
    [47, 107, 142],
    [47, 108, 142],
    [46, 109, 142],
    [46, 110, 142],
    [46, 111, 142],
    [45, 112, 142],
    [45, 113, 142],
    [44, 113, 142],
    [44, 114, 142],
    [44, 115, 142],
    [43, 116, 142],
    [43, 117, 142],
    [42, 118, 142],
    [42, 119, 142],
    [42, 120, 142],
    [41, 121, 142],
    [41, 122, 142],
    [41, 123, 142],
    [40, 124, 142],
    [40, 125, 142],
    [39, 126, 142],
    [39, 127, 142],
    [39, 128, 142],
    [38, 129, 142],
    [38, 130, 142],
    [38, 130, 142],
    [37, 131, 142],
    [37, 132, 142],
    [37, 133, 142],
    [36, 134, 142],
    [36, 135, 142],
    [35, 136, 142],
    [35, 137, 142],
    [35, 138, 141],
    [34, 139, 141],
    [34, 140, 141],
    [34, 141, 141],
    [33, 142, 141],
    [33, 143, 141],
    [33, 144, 141],
    [33, 145, 140],
    [32, 146, 140],
    [32, 146, 140],
    [32, 147, 140],
    [31, 148, 140],
    [31, 149, 139],
    [31, 150, 139],
    [31, 151, 139],
    [31, 152, 139],
    [31, 153, 138],
    [31, 154, 138],
    [30, 155, 138],
    [30, 156, 137],
    [30, 157, 137],
    [31, 158, 137],
    [31, 159, 136],
    [31, 160, 136],
    [31, 161, 136],
    [31, 161, 135],
    [31, 162, 135],
    [32, 163, 134],
    [32, 164, 134],
    [33, 165, 133],
    [33, 166, 133],
    [34, 167, 133],
    [34, 168, 132],
    [35, 169, 131],
    [36, 170, 131],
    [37, 171, 130],
    [37, 172, 130],
    [38, 173, 129],
    [39, 173, 129],
    [40, 174, 128],
    [41, 175, 127],
    [42, 176, 127],
    [44, 177, 126],
    [45, 178, 125],
    [46, 179, 124],
    [47, 180, 124],
    [49, 181, 123],
    [50, 182, 122],
    [52, 182, 121],
    [53, 183, 121],
    [55, 184, 120],
    [56, 185, 119],
    [58, 186, 118],
    [59, 187, 117],
    [61, 188, 116],
    [63, 188, 115],
    [64, 189, 114],
    [66, 190, 113],
    [68, 191, 112],
    [70, 192, 111],
    [72, 193, 110],
    [74, 193, 109],
    [76, 194, 108],
    [78, 195, 107],
    [80, 196, 106],
    [82, 197, 105],
    [84, 197, 104],
    [86, 198, 103],
    [88, 199, 101],
    [90, 200, 100],
    [92, 200, 99],
    [94, 201, 98],
    [96, 202, 96],
    [99, 203, 95],
    [101, 203, 94],
    [103, 204, 92],
    [105, 205, 91],
    [108, 205, 90],
    [110, 206, 88],
    [112, 207, 87],
    [115, 208, 86],
    [117, 208, 84],
    [119, 209, 83],
    [122, 209, 81],
    [124, 210, 80],
    [127, 211, 78],
    [129, 211, 77],
    [132, 212, 75],
    [134, 213, 73],
    [137, 213, 72],
    [139, 214, 70],
    [142, 214, 69],
    [144, 215, 67],
    [147, 215, 65],
    [149, 216, 64],
    [152, 216, 62],
    [155, 217, 60],
    [157, 217, 59],
    [160, 218, 57],
    [162, 218, 55],
    [165, 219, 54],
    [168, 219, 52],
    [170, 220, 50],
    [173, 220, 48],
    [176, 221, 47],
    [178, 221, 45],
    [181, 222, 43],
    [184, 222, 41],
    [186, 222, 40],
    [189, 223, 38],
    [192, 223, 37],
    [194, 223, 35],
    [197, 224, 33],
    [200, 224, 32],
    [202, 225, 31],
    [205, 225, 29],
    [208, 225, 28],
    [210, 226, 27],
    [213, 226, 26],
    [216, 226, 25],
    [218, 227, 25],
    [221, 227, 24],
    [223, 227, 24],
    [226, 228, 24],
    [229, 228, 25],
    [231, 228, 25],
    [234, 229, 26],
    [236, 229, 27],
    [239, 229, 28],
    [241, 229, 29],
    [244, 230, 30],
    [246, 230, 32],
    [248, 230, 33],
    [251, 231, 35],
    [253, 231, 37],
];

/// Given a value in [0, 1], output `sRGB` in Viridis color map.
#[inline]
pub fn viridis_color_map(t: f32) -> [u8; 3] {
    // TODO(andreas): interpolate
    let index = (t * 255.0 + 0.5) as usize;
    VIRIDIS_SRGB_BYTES[index.min(255)]
}