From 2f1285c526a33bafdf4956e1412417b25e1d45be Mon Sep 17 00:00:00 2001 From: Matthew Gordon Date: Mon, 7 Sep 2020 22:48:57 -0400 Subject: [PATCH] Add Spectrum::reflection_from_linear_rgb() --- src/camera.rs | 8 +- src/colour/spectrum.rs | 446 ++++++++++++++++++++++++++- src/main.rs | 14 +- src/materials/lambertian_material.rs | 2 +- 4 files changed, 455 insertions(+), 15 deletions(-) diff --git a/src/camera.rs b/src/camera.rs index 741c34b..5a146e2 100644 --- a/src/camera.rs +++ b/src/camera.rs @@ -106,25 +106,25 @@ pub fn partial_render_scene( let directional_intensity2 = 3.0; let directional_intensity3 = 2.0; let integrator = WhittedIntegrator { - ambient_light: Spectrum::from_linear_rgb( + ambient_light: Spectrum::reflection_from_linear_rgb( &(ColourRgbF::from_named(NamedColour::White) * ambient_intensity), ), lights: vec![ DirectionalLight { direction: Vec3::new(1.0, 1.0, -1.0).normalize(), - spectrum: Spectrum::from_linear_rgb( + spectrum: Spectrum::reflection_from_linear_rgb( &(ColourRgbF::from_named(NamedColour::White) * directional_intensity1), ), }, DirectionalLight { direction: Vec3::new(-0.5, 2.0, -0.5).normalize(), - spectrum: Spectrum::from_linear_rgb( + spectrum: Spectrum::reflection_from_linear_rgb( &(ColourRgbF::from_named(NamedColour::White) * directional_intensity2), ), }, DirectionalLight { direction: Vec3::new(-3.0, 0.1, -0.5).normalize(), - spectrum: Spectrum::from_linear_rgb( + spectrum: Spectrum::reflection_from_linear_rgb( &(ColourRgbF::from_named(NamedColour::White) * directional_intensity3), ), }, diff --git a/src/colour/spectrum.rs b/src/colour/spectrum.rs index 398f2c5..891610f 100644 --- a/src/colour/spectrum.rs +++ b/src/colour/spectrum.rs @@ -1,15 +1,138 @@ -use crate::colour::{ColourRgbF, Photon}; +use crate::colour::{ColourRgbF, Photon, LONGEST_VISIBLE_WAVELENGTH, SHORTEST_VISIBLE_WAVELENGTH}; + +use itertools::izip; #[derive(Debug)] -pub struct Spectrum {} +pub struct Spectrum { + shortest_wavelength: f64, + longest_wavelength: f64, + samples: Vec, +} impl Spectrum { - pub fn from_linear_rgb(colour: &ColourRgbF) -> Spectrum { - Spectrum {} + pub fn black() -> Spectrum { + Spectrum { + shortest_wavelength: SHORTEST_VISIBLE_WAVELENGTH, + longest_wavelength: LONGEST_VISIBLE_WAVELENGTH, + samples: vec![0.0, 0.0], + } + } + + fn wavelength_range(&self) -> f64 { + self.longest_wavelength - self.shortest_wavelength + } + + fn index_at_or_before_wavelength(&self, wavelength: f64) -> usize { + ((self.samples.len() - 1) as f64 + * ((wavelength - self.shortest_wavelength) / self.wavelength_range())) as usize + } + + fn wavelength_at_index(&self, index: usize) -> f64 { + (index as f64) / ((self.samples.len() - 1) as f64) * self.wavelength_range() + + self.shortest_wavelength } pub fn intensity_at_wavelength(&self, wavelength: f64) -> f64 { - 1.0 + if wavelength < self.shortest_wavelength || wavelength > self.longest_wavelength { + 0.0 + } else { + let index_before = self.index_at_or_before_wavelength(wavelength); + let wavelength_before = self.wavelength_at_index(index_before); + if index_before == self.samples.len() - 1 { + self.samples[index_before] + } else { + let wavelength_after = self.wavelength_at_index(index_before + 1); + let delta = wavelength_after - wavelength_before; + let ratio = (wavelength - wavelength_before) / delta; + self.samples[index_before] * (1.0 - ratio) + self.samples[index_before + 1] * ratio + } + } + } + + pub fn reflection_from_linear_rgb(colour: &ColourRgbF) -> Spectrum { + Spectrum { + shortest_wavelength: rgb_reference_spectrum::SHORTEST_WAVELENGTH, + longest_wavelength: rgb_reference_spectrum::LONGEST_WAVELENGTH, + samples: if colour.red() <= colour.green() && colour.red() <= colour.blue() { + if colour.green() <= colour.blue() { + izip![ + rgb_reference_spectrum::reflection::WHITE.iter(), + rgb_reference_spectrum::reflection::CYAN.iter(), + rgb_reference_spectrum::reflection::BLUE.iter() + ] + .map(|(white, cyan, blue)| { + colour.red() * white + + (colour.green() - colour.red()) * cyan + + (colour.blue() - colour.green()) * blue + }) + .collect() + } else { + izip![ + rgb_reference_spectrum::reflection::WHITE.iter(), + rgb_reference_spectrum::reflection::CYAN.iter(), + rgb_reference_spectrum::reflection::GREEN.iter() + ] + .map(|(white, cyan, green)| { + colour.red() * white + + (colour.blue() - colour.red()) * cyan + + (colour.green() - colour.blue()) * green + }) + .collect() + } + } else if colour.green() <= colour.red() && colour.green() < colour.blue() { + if colour.red() <= colour.blue() { + izip![ + rgb_reference_spectrum::reflection::WHITE.iter(), + rgb_reference_spectrum::reflection::MAGENTA.iter(), + rgb_reference_spectrum::reflection::BLUE.iter() + ] + .map(|(white, magenta, blue)| { + colour.green() * white + + (colour.red() - colour.green()) * magenta + + (colour.blue() - colour.red()) * blue + }) + .collect() + } else { + izip![ + rgb_reference_spectrum::reflection::WHITE.iter(), + rgb_reference_spectrum::reflection::MAGENTA.iter(), + rgb_reference_spectrum::reflection::RED.iter() + ] + .map(|(white, magenta, red)| { + colour.green() * white + + (colour.blue() - colour.green()) * magenta + + (colour.red() - colour.blue()) * red + }) + .collect() + } + } else { + if colour.red() <= colour.green() { + izip![ + rgb_reference_spectrum::reflection::WHITE.iter(), + rgb_reference_spectrum::reflection::YELLOW.iter(), + rgb_reference_spectrum::reflection::GREEN.iter() + ] + .map(|(white, yellow, green)| { + colour.blue() * white + + (colour.red() - colour.blue()) * yellow + + (colour.green() - colour.red()) * green + }) + .collect() + } else { + izip![ + rgb_reference_spectrum::reflection::WHITE.iter(), + rgb_reference_spectrum::reflection::YELLOW.iter(), + rgb_reference_spectrum::reflection::RED.iter() + ] + .map(|(white, yellow, red)| { + colour.blue() * white + + (colour.green() - colour.blue()) * yellow + + (colour.red() - colour.green()) * red + }) + .collect() + } + }, + } } pub fn scale_photon(&self, photon: &Photon) -> Photon { @@ -22,3 +145,316 @@ impl Spectrum { photon.set_intensity(self.intensity_at_wavelength(wavelength)) } } + +mod rgb_reference_spectrum { + pub const SHORTEST_WAVELENGTH: f64 = 380.0; + pub const LONGEST_WAVELENGTH: f64 = 720.0; + pub mod reflection { + pub const WHITE: [f64; 32] = [ + 1.0618958571272863e+00, + 1.0615019980348779e+00, + 1.0614335379927147e+00, + 1.0622711654692485e+00, + 1.0622036218416742e+00, + 1.0625059965187085e+00, + 1.0623938486985884e+00, + 1.0624706448043137e+00, + 1.0625048144827762e+00, + 1.0624366131308856e+00, + 1.0620694238892607e+00, + 1.0613167586932164e+00, + 1.0610334029377020e+00, + 1.0613868564828413e+00, + 1.0614215366116762e+00, + 1.0620336151299086e+00, + 1.0625497454805051e+00, + 1.0624317487992085e+00, + 1.0625249140554480e+00, + 1.0624277664486914e+00, + 1.0624749854090769e+00, + 1.0625538581025402e+00, + 1.0625326910104864e+00, + 1.0623922312225325e+00, + 1.0623650980354129e+00, + 1.0625256476715284e+00, + 1.0612277619533155e+00, + 1.0594262608698046e+00, + 1.0599810758292072e+00, + 1.0602547314449409e+00, + 1.0601263046243634e+00, + 1.0606565756823634e+00, + ]; + pub const CYAN: [f64; 32] = [ + 1.0414628021426751e+00, + 1.0328661533771188e+00, + 1.0126146228964314e+00, + 1.0350460524836209e+00, + 1.0078661447098567e+00, + 1.0422280385081280e+00, + 1.0442596738499825e+00, + 1.0535238290294409e+00, + 1.0180776226938120e+00, + 1.0442729908727713e+00, + 1.0529362541920750e+00, + 1.0537034271160244e+00, + 1.0533901869215969e+00, + 1.0537782700979574e+00, + 1.0527093770467102e+00, + 1.0530449040446797e+00, + 1.0550554640191208e+00, + 1.0553673610724821e+00, + 1.0454306634683976e+00, + 6.2348950639230805e-01, + 1.8038071613188977e-01, + -7.6303759201984539e-03, + -1.5217847035781367e-04, + -7.5102257347258311e-03, + -2.1708639328491472e-03, + 6.5919466602369636e-04, + 1.2278815318539780e-02, + -4.4669775637208031e-03, + 1.7119799082865147e-02, + 4.9211089759759801e-03, + 5.8762925143334985e-03, + 2.5259399415550079e-02, + ]; + pub const MAGENTA: [f64; 32] = [ + 9.9422138151236850e-01, + 9.8986937122975682e-01, + 9.8293658286116958e-01, + 9.9627868399859310e-01, + 1.0198955019000133e+00, + 1.0166395501210359e+00, + 1.0220913178757398e+00, + 9.9651666040682441e-01, + 1.0097766178917882e+00, + 1.0215422470827016e+00, + 6.4031953387790963e-01, + 2.5012379477078184e-03, + 6.5339939555769944e-03, + 2.8334080462675826e-03, + -5.1209675389074505e-11, + -9.0592291646646381e-03, + 3.3936718323331200e-03, + -3.0638741121828406e-03, + 2.2203936168286292e-01, + 6.3141140024811970e-01, + 9.7480985576500956e-01, + 9.7209562333590571e-01, + 1.0173770302868150e+00, + 9.9875194322734129e-01, + 9.4701725739602238e-01, + 8.5258623154354796e-01, + 9.4897798581660842e-01, + 9.4751876096521492e-01, + 9.9598944191059791e-01, + 8.6301351503809076e-01, + 8.9150987853523145e-01, + 8.4866492652845082e-01, + ]; + pub const YELLOW: [f64; 32] = [ + 5.5740622924920873e-03, + -4.7982831631446787e-03, + -5.2536564298613798e-03, + -6.4571480044499710e-03, + -5.9693514658007013e-03, + -2.1836716037686721e-03, + 1.6781120601055327e-02, + 9.6096355429062641e-02, + 2.1217357081986446e-01, + 3.6169133290685068e-01, + 5.3961011543232529e-01, + 7.4408810492171507e-01, + 9.2209571148394054e-01, + 1.0460304298411225e+00, + 1.0513824989063714e+00, + 1.0511991822135085e+00, + 1.0510530911991052e+00, + 1.0517397230360510e+00, + 1.0516043086790485e+00, + 1.0511944032061460e+00, + 1.0511590325868068e+00, + 1.0516612465483031e+00, + 1.0514038526836869e+00, + 1.0515941029228475e+00, + 1.0511460436960840e+00, + 1.0515123758830476e+00, + 1.0508871369510702e+00, + 1.0508923708102380e+00, + 1.0477492815668303e+00, + 1.0493272144017338e+00, + 1.0435963333422726e+00, + 1.0392280772051465e+00, + ]; + pub const RED: [f64; 32] = [ + 1.6575604867086180e-01, + 1.1846442802747797e-01, + 1.2408293329637447e-01, + 1.1371272058349924e-01, + 7.8992434518899132e-02, + 3.2205603593106549e-02, + -1.0798365407877875e-02, + 1.8051975516730392e-02, + 5.3407196598730527e-03, + 1.3654918729501336e-02, + -5.9564213545642841e-03, + -1.8444365067353252e-03, + -1.0571884361529504e-02, + -2.9375521078000011e-03, + -1.0790476271835936e-02, + -8.0224306697503633e-03, + -2.2669167702495940e-03, + 7.0200240494706634e-03, + -8.1528469000299308e-03, + 6.0772866969252792e-01, + 9.8831560865432400e-01, + 9.9391691044078823e-01, + 1.0039338994753197e+00, + 9.9234499861167125e-01, + 9.9926530858855522e-01, + 1.0084621557617270e+00, + 9.8358296827441216e-01, + 1.0085023660099048e+00, + 9.7451138326568698e-01, + 9.8543269570059944e-01, + 9.3495763980962043e-01, + 9.8713907792319400e-01, + ]; + pub const GREEN: [f64; 32] = [ + 2.6494153587602255e-03, + -5.0175013429732242e-03, + -1.2547236272489583e-02, + -9.4554964308388671e-03, + -1.2526086181600525e-02, + -7.9170697760437767e-03, + -7.9955735204175690e-03, + -9.3559433444469070e-03, + 6.5468611982999303e-02, + 3.9572875517634137e-01, + 7.5244022299886659e-01, + 9.6376478690218559e-01, + 9.9854433855162328e-01, + 9.9992977025287921e-01, + 9.9939086751140449e-01, + 9.9994372267071396e-01, + 9.9939121813418674e-01, + 9.9911237310424483e-01, + 9.6019584878271580e-01, + 6.3186279338432438e-01, + 2.5797401028763473e-01, + 9.4014888527335638e-03, + -3.0798345608649747e-03, + -4.5230367033685034e-03, + -6.8933410388274038e-03, + -9.0352195539015398e-03, + -8.5913667165340209e-03, + -8.3690869120289398e-03, + -7.8685832338754313e-03, + -8.3657578711085132e-06, + 5.4301225442817177e-03, + -2.7745589759259194e-03, + ]; + pub const BLUE: [f64; 32] = [ + 9.9209771469720676e-01, + 9.8876426059369127e-01, + 9.9539040744505636e-01, + 9.9529317353008218e-01, + 9.9181447411633950e-01, + 1.0002584039673432e+00, + 9.9968478437342512e-01, + 9.9988120766657174e-01, + 9.8504012146370434e-01, + 7.9029849053031276e-01, + 5.6082198617463974e-01, + 3.3133458513996528e-01, + 1.3692410840839175e-01, + 1.8914906559664151e-02, + -5.1129770932550889e-06, + -4.2395493167891873e-04, + -4.1934593101534273e-04, + 1.7473028136486615e-03, + 3.7999160177631316e-03, + -5.5101474906588642e-04, + -4.3716662898480967e-05, + 7.5874501748732798e-03, + 2.5795650780554021e-02, + 3.8168376532500548e-02, + 4.9489586408030833e-02, + 4.9595992290102905e-02, + 4.9814819505812249e-02, + 3.9840911064978023e-02, + 3.0501024937233868e-02, + 2.1243054765241080e-02, + 6.9596532104356399e-03, + 4.1733649330980525e-03, + ]; + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn intensity_at_wavelength_returns_expected_value_at_minimum_wavelength() { + let target = Spectrum { + shortest_wavelength: 400.5, + longest_wavelength: 700.25, + samples: vec![0.5, 1.0, 0.75, 1.5], + }; + assert!(target.intensity_at_wavelength(400.5) == 0.5) + } + + #[test] + fn intensity_at_wavelength_returns_expected_value_at_max_wavelength() { + let target = Spectrum { + shortest_wavelength: 400.5, + longest_wavelength: 700.25, + samples: vec![0.5, 1.0, 0.75, 1.5], + }; + assert!(target.intensity_at_wavelength(700.25) == 1.5) + } + + #[test] + fn intensity_at_wavelength_returns_expected_value_at_interior_sample_wavelength() { + let target = Spectrum { + shortest_wavelength: 400.0, + longest_wavelength: 700.0, + samples: vec![0.5, 1.0, 0.75, 1.5], + }; + assert!(target.intensity_at_wavelength(500.0) == 1.0); + assert!(target.intensity_at_wavelength(600.0) == 0.75); + } + + #[test] + fn intensity_at_wavelength_returns_expected_value_at_halfway_between_sample_wavelength() { + let target = Spectrum { + shortest_wavelength: 400.0, + longest_wavelength: 700.0, + samples: vec![0.5, 1.0, 0.75, 1.5], + }; + assert!(target.intensity_at_wavelength(450.0) == 0.75); + assert!(target.intensity_at_wavelength(550.0) == 0.875); + assert!(target.intensity_at_wavelength(650.0) == 1.125); + } + + #[test] + fn intensity_below_minimum_wavelength_is_zero() { + let target = Spectrum { + shortest_wavelength: 400.0, + longest_wavelength: 700.0, + samples: vec![0.5, 1.0, 0.75, 1.5], + }; + assert!(target.intensity_at_wavelength(399.9999) == 0.0); + } + + #[test] + fn intensity_above_maximum_wavelength_is_zero() { + let target = Spectrum { + shortest_wavelength: 400.0, + longest_wavelength: 700.0, + samples: vec![0.5, 1.0, 0.75, 1.5], + }; + assert!(target.intensity_at_wavelength(700.0001) == 0.0); + } +} diff --git a/src/main.rs b/src/main.rs index 4be0ee5..b3495b9 100644 --- a/src/main.rs +++ b/src/main.rs @@ -123,7 +123,9 @@ pub fn main() -> Result<(), Box> { let mut model_object = load_obj( &model_file_path, Arc::new(ReflectiveMaterial { - colour: Spectrum::from_linear_rgb(&ColourRgbF::from_named(NamedColour::Yellow)), + colour: Spectrum::reflection_from_linear_rgb(&ColourRgbF::from_named( + NamedColour::Yellow, + )), diffuse_strength: 0.05, reflection_strength: 0.9, }), @@ -141,7 +143,9 @@ pub fn main() -> Result<(), Box> { Vec3::new(0.0, 1.0, 0.0), -2.0, Arc::new(LambertianMaterial { - colour: Spectrum::from_linear_rgb(&ColourRgbF::new(0.55, 0.27, 0.04)), + colour: Spectrum::reflection_from_linear_rgb(&ColourRgbF::new( + 0.55, 0.27, 0.04, + )), diffuse_strength: 0.1, }), )) as Box, @@ -149,7 +153,7 @@ pub fn main() -> Result<(), Box> { Vec3::new(-6.25, -0.5, 1.0), 1.0, Arc::new(LambertianMaterial { - colour: Spectrum::from_linear_rgb(&ColourRgbF::from_named( + colour: Spectrum::reflection_from_linear_rgb(&ColourRgbF::from_named( NamedColour::Green, )), diffuse_strength: 0.1, @@ -159,7 +163,7 @@ pub fn main() -> Result<(), Box> { Vec3::new(-4.25, -0.5, 2.0), 1.0, Arc::new(ReflectiveMaterial { - colour: Spectrum::from_linear_rgb(&ColourRgbF::from_named( + colour: Spectrum::reflection_from_linear_rgb(&ColourRgbF::from_named( NamedColour::Blue, )), diffuse_strength: 0.01, @@ -170,7 +174,7 @@ pub fn main() -> Result<(), Box> { Vec3::new(-5.0, 1.5, 1.0), 1.0, Arc::new(PhongMaterial { - colour: Spectrum::from_linear_rgb(&ColourRgbF::from_named( + colour: Spectrum::reflection_from_linear_rgb(&ColourRgbF::from_named( NamedColour::Red, )), diffuse_strength: 0.05, diff --git a/src/materials/lambertian_material.rs b/src/materials/lambertian_material.rs index bed4d00..341f553 100644 --- a/src/materials/lambertian_material.rs +++ b/src/materials/lambertian_material.rs @@ -14,7 +14,7 @@ pub struct LambertianMaterial { impl LambertianMaterial { pub fn new_dummy() -> LambertianMaterial { LambertianMaterial { - colour: Spectrum {}, + colour: Spectrum::black(), diffuse_strength: 1.0, } }