Struct MTKSubmesh

Source

#[repr(C)]
pub struct MTKSubmesh { /* private fields */ }

Available on crate feature MTKModel only.

Expand description

A segment of a mesh and properties to render the segement.

Container for data that can be rendered in a single draw call. 1:1 mapping to MDLSubmesh. Each submesh contains an index Buffer with which the parents mesh data can be rendered. Actual vertex data resides in the submesh’s parent MTKMesh object.

Implementations§

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impl MTKSubmesh

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

Applicatiohs must not explicity allocate or initialize. Must initialize as part of MTKMesh object.

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pub unsafe fn primitiveType(&self) -> MTLPrimitiveType

Metal primitive type with which to draw this object.

Value to use for primitiveType parameter in a [MTLRenderCommandEncoder drawIndexedPrimitives] call.

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pub unsafe fn indexType(&self) -> MTLIndexType

Metal index type of data in indexBuffer.

Value to use for indexType parameter in a [MTLRenderCommandEncoder drawIndexedPrimitives] call.

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pub unsafe fn indexBuffer(&self) -> Retained<MTKMeshBuffer>

IndexBuffer (including indexCount) to render the object.

The MTLBuffer to use for indexBuffer parameter in a [MTLRenderCommandEncoder drawIndexedPrimitives] call.

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pub unsafe fn indexCount(&self) -> NSUInteger

Number of indicies in indexBuffer.

Value to use for indexCount parameter in a [MTLRenderCommandEncoder drawIndexedPrimitives] call.

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pub unsafe fn mesh(&self) -> Option<Retained<MTKMesh>>

Parent MTKMesh object containing vertex data of this object.

The buffer of this parent mesh should be set in the encoder before a drawIndexedPrimitives call is made.

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pub unsafe fn name(&self) -> Retained<NSString>

Name from the original MDLSubmesh object.

Although not directly used by this object, the application may use this to identify the submesh in the renderer/scene/world.

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pub unsafe fn setName(&self, name: &NSString)

Setter for name.

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impl MTKSubmesh

Methods declared on superclass NSObject.

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pub unsafe 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.

§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`
    }
}