add proptest usage within ggx tests, along with some fixtures/prop_co…

…mpose invocations

Cargo.toml

@@ -71,8 +71,12 @@ tobj = "~4.0"
 toml = "~0.8"
 tracing = "~0.1"
 tracing-subscriber = "~0.3"
+# pinning to 0.8 because of crate version reasons
 ultraviolet = { version = "~0.8", optional = true }
 
+[dev-dependencies]
+proptest = "1.5.0"
+
 [target.'cfg(windows)'.dependencies]
 win32_notification = "~0.1"
 

proptest-regressions/materials/ggx.txt

@@ -0,0 +1,7 @@
+# Seeds for failure cases proptest has generated in the past. It is
+# automatically read and these particular cases re-run before any
+# novel cases are generated.
+#
+# It is recommended to check this file in to source control so that
+# everyone who runs the test benefits from these saved cases.
+cc 9c0ae291d4fb1b0b7461c99518df9126afd836caa7b93dadd6772b8c1f81fb26 # shrinks to roughness = 8.736748, wi = Vec3(0.54826164, 0.0, -0.83630687), lambda = 400.0, s = Sample2D { x: 0.0, y: 0.0 }

src/lib.rs

@@ -39,6 +39,9 @@ pub mod tonemap;
 pub mod vec2d;
 pub mod world;
 
+#[cfg(test)]
+pub mod props;
+
 // mauve. universal sign of danger
 pub const MAUVE: XYZColor = XYZColor::new(0.5199467, 51.48687, 1.0180528);
 

src/materials/ggx.rs

@@ -599,6 +599,8 @@ impl Material<f32, f32> for GGX {
 
 #[cfg(test)]
 mod test {
+    use proptest::prelude::*;
+    use crate::props::*;
 
     use math::spectral::BOUNDED_VISIBLE_RANGE;
     use rayon::iter::{IntoParallelIterator, ParallelIterator};
@@ -632,6 +634,127 @@ mod test {
         GGX::new(roughness, glass, flat_one, flat_zero, 0, 0)
     }
 
+    proptest! {
+        #![proptest_config(ProptestConfig::with_cases(1000))]
+        #[test]
+        fn test_ggx(roughness in valid_ggx_roughness(), wi in unit_vector(), lambda in 400.0..800.0f32, s in uniform_sample()) {
+            let ggx_glass = ggx_glass(roughness);
+            let fake_hit_record: HitRecord = HitRecord::new(
+                0.0,
+                Point3::ZERO,
+                UV(0.0f32, 0.0f32),
+                lambda,
+                Vec3::Z,
+                MaterialId::Material(0),
+                0,
+                None,
+            );
+
+            let maybe_wo = ggx_glass.generate(
+                fake_hit_record.lambda,
+                fake_hit_record.uv,
+                fake_hit_record.transport_mode,
+                s,
+                wi,
+            );
+            assert!(maybe_wo.is_some());
+
+            let wo = maybe_wo.unwrap();
+            let (orig_f, orig_pdf) = ggx_glass.bsdf(
+                fake_hit_record.lambda,
+                fake_hit_record.uv,
+                fake_hit_record.transport_mode,
+                wi,
+                wo,
+            );
+
+            // check swapping wi and wo
+            let (wi, wo) = (wo, wi);
+            let (sampled_f, sampled_pdf) = ggx_glass.bsdf(
+                fake_hit_record.lambda,
+                fake_hit_record.uv,
+                fake_hit_record.transport_mode,
+                wi,
+                wo,
+            );
+            assert!(sampled_f > 0.0, "original f: {:?}, pdf: {:?}, swapped f: {:?}, pdf: {:?}, swapped wi: {:?}, wo: {:?}", orig_f, orig_pdf, sampled_f, sampled_pdf, wi, wo);
+            assert!(*sampled_pdf >= 0.0, "original f: {:?}, pdf: {:?}, swapped f: {:?}, pdf: {:?}, swapped wi: {:?}, wo: {:?}",  orig_f, orig_pdf, sampled_f, sampled_pdf, wi, wo);
+            assert!(orig_f > 0.0, "original f: {:?}, pdf: {:?}, swapped f: {:?}, pdf: {:?}, swapped wi: {:?}, wo: {:?}", orig_f, orig_pdf, sampled_f, sampled_pdf, wi, wo);
+            assert!(*orig_pdf >= 0.0, "original f: {:?}, pdf: {:?}, swapped f: {:?}, pdf: {:?}, swapped wi: {:?}, wo: {:?}", orig_f, orig_pdf, sampled_f, sampled_pdf, wi, wo);
+
+        }
+
+        #[test]
+        fn test_ggx2(roughness in valid_ggx_roughness(), wi in unit_vector(), wo in unit_vector(), lambda in 400.0..800.0f32) {
+            let ggx_glass = ggx_glass(roughness);
+            let fake_hit_record: HitRecord = HitRecord::new(
+                0.0,
+                Point3::ZERO,
+                UV(0.0f32, 0.0f32),
+                lambda,
+                Vec3::Z,
+                MaterialId::Material(0),
+                0,
+                None,
+            );
+            let (orig_f, orig_pdf) = ggx_glass.bsdf(
+                fake_hit_record.lambda,
+                fake_hit_record.uv,
+                fake_hit_record.transport_mode,
+                wi,
+                wo,
+            );
+            let (wi, wo) = (wo, wi);
+            let (sampled_f, sampled_pdf) = ggx_glass.bsdf(
+                fake_hit_record.lambda,
+                fake_hit_record.uv,
+                fake_hit_record.transport_mode,
+                wi,
+                wo,
+            );
+            assert!(
+                sampled_f >= 0.0,
+                "original f: {:?}, pdf: {:?}, swapped f: {:?}, pdf: {:?}, swapped wi: {:?}, wo: {:?}",
+                orig_f,
+                orig_pdf,
+                sampled_f,
+                sampled_pdf,
+                wi,
+                wo
+            );
+            assert!(
+                *sampled_pdf >= 0.0,
+                "original f: {:?}, pdf: {:?}, swapped f: {:?}, pdf: {:?}, swapped wi: {:?}, wo: {:?}",
+                orig_f,
+                orig_pdf,
+                sampled_f,
+                sampled_pdf,
+                wi,
+                wo
+            );
+            assert!(
+                orig_f >= 0.0,
+                "original f: {:?}, pdf: {:?}, swapped f: {:?}, pdf: {:?}, swapped wi: {:?}, wo: {:?}",
+                orig_f,
+                orig_pdf,
+                sampled_f,
+                sampled_pdf,
+                wi,
+                wo
+            );
+            assert!(
+                *orig_pdf >= 0.0,
+                "original f: {:?}, pdf: {:?}, swapped f: {:?}, pdf: {:?}, swapped wi: {:?}, wo: {:?}",
+                orig_f,
+                orig_pdf,
+                sampled_f,
+                sampled_pdf,
+                wi,
+                wo
+            );
+        }
+    }
+
     #[test]
     fn test_ggx_functions() {
         let mut sampler: Box<dyn Sampler> = Box::new(StratifiedSampler::new(20, 20, 10));

src/props.rs

@@ -0,0 +1,20 @@
+use math::{random::random_on_unit_sphere, sample::Sample2D, vec::Vec3};
+use proptest::prelude::*;
+
+prop_compose! {
+    pub fn uniform_sample()(u in 0.0..1.0f32, v in 0.0..1.0f32) -> Sample2D {
+        Sample2D::new(u, v)
+    }
+}
+
+prop_compose! {
+    pub fn valid_ggx_roughness()(x in 0.0..1.0f32) -> f32 {
+        (-(x+f32::EPSILON).ln()).recip()
+    }
+}
+
+prop_compose! {
+    pub fn unit_vector()(s in uniform_sample()) -> Vec3 {
+        random_on_unit_sphere(s)
+    }
+}