Struct MTL4AccelerationStructureGeometryDescriptor

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pub struct MTL4AccelerationStructureGeometryDescriptor { /* private fields */ }

Available on crate feature MTL4AccelerationStructure only.

Expand description

Base class for all Metal 4 acceleration structure geometry descriptors.

Don’t use this class directly. Use one of the derived classes instead.

Implementations§

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impl MTL4AccelerationStructureGeometryDescriptor

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pub fn intersectionFunctionTableOffset(&self) -> NSUInteger

Sets the offset that this geometry contributes to determining the intersection function to invoke when a ray intersects it.

When you perform a ray tracing operation in the Metal Shading Language, and provide the ray intersector object with an instance of MTLIntersectionFunctionTable, Metal adds this offset to the instance offset from structs such as:

MTLAccelerationStructureInstanceDescriptor
MTLAccelerationStructureUserIDInstanceDescriptor
MTLAccelerationStructureMotionInstanceDescriptor
MTLIndirectAccelerationStructureInstanceDescriptor
MTLIndirectAccelerationStructureMotionInstanceDescriptor

The sum of these offsets provides an index into the intersection function table that the ray tracing system uses to retrieve and invoke the function at this index, allowing you to customize the intersection evaluation process.

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pub unsafe fn setIntersectionFunctionTableOffset( &self, intersection_function_table_offset: NSUInteger, )

Setter for intersectionFunctionTableOffset.

§Safety

This might not be bounds-checked.

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pub fn opaque(&self) -> bool

Provides a hint to Metal that this geometry is opaque, potentially accelerating the ray/primitive intersection process.

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pub fn setOpaque(&self, opaque: bool)

Setter for opaque.

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pub fn allowDuplicateIntersectionFunctionInvocation(&self) -> bool

A boolean value that indicates whether the ray-tracing system in Metal allows the invocation of intersection functions more than once per ray-primitive intersection.

The property’s default value is <doc ://com.apple.documentation/documentation/swift/true>.

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pub fn setAllowDuplicateIntersectionFunctionInvocation( &self, allow_duplicate_intersection_function_invocation: bool, )

Setter for allowDuplicateIntersectionFunctionInvocation.

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pub fn label(&self) -> Option<Retained<NSString>>

Assigns an optional label you can assign to this geometry for debugging purposes.

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pub fn setLabel(&self, label: Option<&NSString>)

Setter for label.

This is copied when set.

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pub fn primitiveDataBuffer(&self) -> MTL4BufferRange

Available on crate features MTL4BufferRange and MTLGPUAddress only.

Assigns optional buffer containing data to associate with each primitive in this geometry.

You can use zero as the buffer address in this buffer range.

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pub unsafe fn setPrimitiveDataBuffer( &self, primitive_data_buffer: MTL4BufferRange, )

Available on crate features MTL4BufferRange and MTLGPUAddress only.

Setter for primitiveDataBuffer.

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pub fn primitiveDataStride(&self) -> NSUInteger

Defines the stride, in bytes, between each primitive’s data in the primitive data buffer primitiveDataBuffer references.

You are responsible for ensuring the stride is at least primitiveDataElementSize in size and a multiple of 4 bytes.

This property defaults to 0 bytes, which indicates the stride is equal to primitiveDataElementSize.

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pub unsafe fn setPrimitiveDataStride(&self, primitive_data_stride: NSUInteger)

Setter for primitiveDataStride.

§Safety

This might not be bounds-checked.

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pub fn primitiveDataElementSize(&self) -> NSUInteger

Sets the size, in bytes, of the data for each primitive in the primitive data buffer primitiveDataBuffer references.

This size needs to be at most primitiveDataStride in size and a multiple of 4 bytes.

This property defaults to 0 bytes.

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pub unsafe fn setPrimitiveDataElementSize( &self, primitive_data_element_size: NSUInteger, )

Setter for primitiveDataElementSize.

§Safety

This might not be bounds-checked.

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impl MTL4AccelerationStructureGeometryDescriptor

Methods declared on superclass NSObject.

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pub fn init(this: Allocated<Self>) -> Retained<Self>

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pub fn new() -> Retained<Self>

Methods from Deref<Target = NSObject>§

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pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

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pub fn class(&self) -> &'static AnyClass

Dynamically find the class of this object.

§Panics

May panic if the object is invalid (which may be the case for objects returned from unavailable init/new methods).

§Example

Check that an instance of NSObject has the precise class NSObject.

use objc2::ClassType;
use objc2::runtime::NSObject;

let obj = NSObject::new();
assert_eq!(obj.class(), NSObject::class());

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pub unsafe fn get_ivar<T>(&self, name: &str) -> &T
where T: Encode,

👎Deprecated: this is difficult to use correctly, use Ivar::load instead.

Use Ivar::load instead.

§Safety

The object must have an instance variable with the given name, and it must be of type T.

See Ivar::load_ptr for details surrounding this.

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pub fn downcast_ref<T>(&self) -> Option<&T>
where T: DowncastTarget,

Attempt to downcast the object to a class of type T.

This is the reference-variant. Use Retained::downcast if you want to convert a retained object to another type.

§Mutable classes

Some classes have immutable and mutable variants, such as NSString and NSMutableString.

When some Objective-C API signature says it gives you an immutable class, it generally expects you to not mutate that, even though it may technically be mutable “under the hood”.

So using this method to convert a NSString to a NSMutableString, while not unsound, is generally frowned upon unless you created the string yourself, or the API explicitly documents the string to be mutable.

See Apple’s documentation on mutability and on isKindOfClass: for more details.

§Generic classes

Objective-C generics are called “lightweight generics”, and that’s because they aren’t exposed in the runtime. This makes it impossible to safely downcast to generic collections, so this is disallowed by this method.

You can, however, safely downcast to generic collections where all the type-parameters are AnyObject.

§Panics

This works internally by calling isKindOfClass:. That means that the object must have the instance method of that name, and an exception will be thrown (if CoreFoundation is linked) or the process will abort if that is not the case. In the vast majority of cases, you don’t need to worry about this, since both root objects NSObject and NSProxy implement this method.

§Examples

Cast an NSString back and forth from NSObject.

use objc2::rc::Retained;
use objc2_foundation::{NSObject, NSString};

let obj: Retained<NSObject> = NSString::new().into_super();
let string = obj.downcast_ref::<NSString>().unwrap();
// Or with `downcast`, if we do not need the object afterwards
let string = obj.downcast::<NSString>().unwrap();

Try (and fail) to cast an NSObject to an NSString.

use objc2_foundation::{NSObject, NSString};

let obj = NSObject::new();
assert!(obj.downcast_ref::<NSString>().is_none());

Try to cast to an array of strings.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);
// This is invalid and doesn't type check.
let arr = arr.downcast_ref::<NSArray<NSString>>();

This fails to compile, since it would require enumerating over the array to ensure that each element is of the desired type, which is a performance pitfall.

Downcast when processing each element instead.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);

for elem in arr {
    if let Some(data) = elem.downcast_ref::<NSString>() {
        // handle `data`
    }
}