Rethink SurfaceInteraction regarding C++ mutable members
wahn opened this issue · 6 comments
In C++ the class SurfaceInteraction looks like this:
class SurfaceInteraction : public Interaction {
public:
...
mutable Vector3f dpdx, dpdy;
mutable Float dudx = 0, dvdx = 0, dudy = 0, dvdy = 0;
...
}; Most likely we should try to use Rust's interior mutability, e.g. RefCell. See C++ vs Rust and search for mutable keyword.
From the module cell documentation:
Consider using
RwLock<T>orMutex<T>if you need shared mutability in a multi-threaded situation.
I created a branch (issue_114) for this issue. Currently the Rust side looks like this:
pub struct SurfaceInteraction<'p, 's> {
// Interaction Public Data
pub p: Point3f,
pub time: Float,
pub p_error: Vector3f,
pub wo: Vector3f,
pub n: Normal3f,
pub medium_interface: Option<Arc<MediumInterface>>,
// SurfaceInteraction Public Data
pub uv: Point2f,
pub dpdu: Vector3f,
pub dpdv: Vector3f,
pub dndu: Normal3f,
pub dndv: Normal3f,
pub dpdx: RwLock<Vector3f>,
pub dpdy: RwLock<Vector3f>,
pub dudx: RwLock<Float>,
pub dvdx: RwLock<Float>,
pub dudy: RwLock<Float>,
pub dvdy: RwLock<Float>,
pub primitive: Option<&'p GeometricPrimitive>,
pub shading: Shading,
pub bsdf: Option<Arc<Bsdf>>,
pub bssrdf: Option<Arc<TabulatedBssrdf>>,
pub shape: Option<&'s dyn Shape>,
}I made the remaining files compile, but the mlt and bdpt algorithms had to be removed. I think I have to find a better solution for the pointers involved. On the C++ side they are part of a struct and a class:
struct Interaction {
...
MediumInterface mediumInterface;
};
...
class SurfaceInteraction : public Interaction {
...
const Shape *shape = nullptr;
...
const Primitive *primitive = nullptr;
BSDF *bsdf = nullptr;
BSSRDF *bssrdf = nullptr;
}; After commit 031de34 we got rid of the lifetimes:
pub struct SurfaceInteraction {
// Interaction Public Data
pub p: Point3f,
pub time: Float,
pub p_error: Vector3f,
pub wo: Vector3f,
pub n: Normal3f,
pub medium_interface: Option<Arc<MediumInterface>>,
// SurfaceInteraction Public Data
pub uv: Point2f,
pub dpdu: Vector3f,
pub dpdv: Vector3f,
pub dndu: Normal3f,
pub dndv: Normal3f,
pub dpdx: RwLock<Vector3f>,
pub dpdy: RwLock<Vector3f>,
pub dudx: RwLock<Float>,
pub dvdx: RwLock<Float>,
pub dudy: RwLock<Float>,
pub dvdy: RwLock<Float>,
pub primitive: Option<Arc<dyn Primitive + Send + Sync>>,
pub shading: Shading,
pub bsdf: Option<Arc<Bsdf>>,
pub bssrdf: Option<Arc<TabulatedBssrdf>>,
pub shape: Option<Arc<dyn Shape + Send + Sync>>,
} Let's see if we can make the mlt and bdpt algorithms work again ...
After commit e5ca87e bidirectional pathtracing works again:
> ./target/release/rs_pbrt -i assets/scenes/cafe_scene2.pbrt
...
Integrator "bdpt"
"integer maxdepth" [3]
...
Rendering with 8 thread(s) ...
1024 / 1024 [=======================================================================] 100.00 % 12.19/s
Writing image "pbrt.png" with bounds Bounds2 { p_min: Point2 { x: 0, y: 0 }, p_max: Point2 { x: 500, y: 500 } }
Now we just need mlt to work again before we can merge the branch back to the master branch.