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multigpu: Less constraints around framebuffers #1816

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38ad389
multigpu: Remove left-over allocator generic
Drakulix Sep 3, 2025
0f68962
multigpu: Add a way to access target renderer
Drakulix Sep 3, 2025
30f6405
multigpu: Lift some unnecessary R-constraints
Drakulix Sep 3, 2025
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189 changes: 150 additions & 39 deletions src/backend/renderer/multigpu/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -356,13 +356,10 @@ impl<A: GraphicsApi> GpuManager<A> {
/// - `target_api` should be the [`GpuManager`] used for the `target_device`.
/// - `render_device` should referr to the gpu node rendering operations will take place upon.
/// - `target_device` should referr to the gpu node the composited buffer will end up upon
/// - `allocator` should referr to an `Allocator`, that works guaranteed with the `render_device`
/// to do offscreen composition on. Dma copies will be used, if buffers returned by the allocator
/// also work on the `target_device`.
/// - `copy_format` denotes the format buffers will be allocated in for offscreen rendering.
#[instrument(level = "trace", skip(render_api, target_api), follows_from = [&render_api.span, &target_api.span])]
#[profiling::function]
pub fn cross_renderer<'render, 'target, B: GraphicsApi, Alloc: Allocator>(
pub fn cross_renderer<'render, 'target, B: GraphicsApi>(
render_api: &'render mut Self,
target_api: &'target mut GpuManager<B>,
render_device: &DrmNode,
Expand Down Expand Up @@ -767,16 +764,51 @@ impl<R: GraphicsApi, T: GraphicsApi> AsMut<<R::Device as ApiDevice>::Renderer>
}
}

impl<'render, 'target, R: GraphicsApi, T: GraphicsApi> MultiRenderer<'render, 'target, R, T> {
/// Converts this renderer into a reference of the target-device's renderer,
/// if it diverges from the render-device.
pub fn target_as_ref(&self) -> Option<&<T::Device as ApiDevice>::Renderer> {
self.target.as_ref().map(|data| data.device.renderer())
}

/// Converts this renderer into a mutable reference of the target-device's renderer,
/// if it diverges from the render-device.
pub fn target_as_mut(&mut self) -> Option<&mut <T::Device as ApiDevice>::Renderer> {
self.target.as_mut().map(|data| data.device.renderer_mut())
}

/// Converts this `MultiRenderer` into a `single_renderer` for the provided target device.
///
/// Will return the current renderer, if it is already a single-device render.
pub fn into_target(self) -> MultiRenderer<'target, 'target, T, T> {
if let Some(target) = self.target {
MultiRenderer {
render: target.device,
target: None,
other_renderers: Vec::new(),
span: self.span,
}
} else {
// Safety: We know R == T and thus 'render == 'target, if target is `None`.
unsafe {
std::mem::transmute::<
MultiRenderer<'render, 'target, R, T>,
MultiRenderer<'target, 'target, T, T>,
>(self)
}
}
}
}

/// A Framebuffer of a [`MultiRenderer`].
pub struct MultiFramebuffer<'buffer, R: GraphicsApi, T: GraphicsApi>(MultiFramebufferInternal<'buffer, R, T>);
enum MultiFramebufferInternal<'buffer, R: GraphicsApi, T: GraphicsApi> {
Render(<<R::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'buffer>),
pub struct MultiFramebuffer<'buffer, T: GraphicsApi>(MultiFramebufferInternal<'buffer, T>);
enum MultiFramebufferInternal<'buffer, T: GraphicsApi> {
Render(<<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'buffer>),
Target(<<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'buffer>),
}

impl<'buffer, R: GraphicsApi, T: GraphicsApi> fmt::Debug for MultiFramebuffer<'buffer, R, T>
impl<'buffer, T: GraphicsApi> fmt::Debug for MultiFramebuffer<'buffer, T>
where
<<R::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'buffer>: fmt::Debug,
<<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'buffer>: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
Expand All @@ -787,7 +819,7 @@ where
}
}

impl<R: GraphicsApi, T: GraphicsApi> Texture for MultiFramebuffer<'_, R, T> {
impl<T: GraphicsApi> Texture for MultiFramebuffer<'_, T> {
fn size(&self) -> Size<i32, BufferCoords> {
match &self.0 {
MultiFramebufferInternal::Render(framebuffer) => framebuffer.size(),
Expand Down Expand Up @@ -817,6 +849,28 @@ impl<R: GraphicsApi, T: GraphicsApi> Texture for MultiFramebuffer<'_, R, T> {
}
}

impl<'a, T: GraphicsApi> AsRef<<<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'a>>
for MultiFramebuffer<'a, T>
{
fn as_ref(&self) -> &<<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'a> {
match &self.0 {
MultiFramebufferInternal::Render(fb) => fb,
MultiFramebufferInternal::Target(fb) => fb,
}
}
}

impl<'a, T: GraphicsApi> AsMut<<<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'a>>
for MultiFramebuffer<'a, T>
{
fn as_mut(&mut self) -> &mut <<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'a> {
match &mut self.0 {
MultiFramebufferInternal::Render(fb) => fb,
MultiFramebufferInternal::Target(fb) => fb,
}
}
}

/// [`Frame`] implementation of a [`MultiRenderer`].
///
/// Leaking the frame will potentially keep it from doing necessary copies
Expand Down Expand Up @@ -960,10 +1014,8 @@ where
impl<R: GraphicsApi, T: GraphicsApi, Target> Offscreen<Target> for MultiRenderer<'_, '_, R, T>
where
<T::Device as ApiDevice>::Renderer: Offscreen<Target>,
<R::Device as ApiDevice>::Renderer: Offscreen<Target>,
// We need these because the Bind-impl does and Offscreen requires Bind
<T::Device as ApiDevice>::Renderer: Bind<Target>,
<R::Device as ApiDevice>::Renderer: Bind<Target>,
// We need these because the Renderer-impl does and Offscreen requires Bind, which requires Unbind, which requires Renderer
R: 'static,
R::Error: 'static,
Expand All @@ -988,18 +1040,21 @@ where
.create_buffer(format, size)
.map_err(Error::Target)
} else {
self.render
.renderer_mut()
.create_buffer(format, size)
.map_err(Error::Render)
// SAFETY: We know this is safe, because `self.target` can only be `None` if R == T.
let renderer = unsafe {
std::mem::transmute::<
&mut <R::Device as ApiDevice>::Renderer,
&mut <T::Device as ApiDevice>::Renderer,
>(self.render.renderer_mut())
};
renderer.create_buffer(format, size).map_err(Error::Target)
}
}
}

impl<R: GraphicsApi, T: GraphicsApi, Target> Bind<Target> for MultiRenderer<'_, '_, R, T>
where
<T::Device as ApiDevice>::Renderer: Bind<Target>,
<R::Device as ApiDevice>::Renderer: Bind<Target>,
// We need this because the Renderer-impl does and Bind requires Unbind, which requires Renderer
R: 'static,
R::Error: 'static,
Expand All @@ -1025,20 +1080,32 @@ where
.map(MultiFramebuffer)
.map_err(Error::Target)
} else {
self.render
.renderer_mut()
// SAFETY: We know this is safe, because `self.target` can only be `None` if R == T.
let renderer = unsafe {
std::mem::transmute::<
&mut <R::Device as ApiDevice>::Renderer,
&mut <T::Device as ApiDevice>::Renderer,
>(self.render.renderer_mut())
};
renderer
.bind(bind)
.map(MultiFramebufferInternal::Render)
.map(MultiFramebuffer)
.map_err(Error::Render)
.map_err(Error::Target)
}
}

fn supported_formats(&self) -> Option<FormatSet> {
if let Some(target) = self.target.as_ref() {
Bind::<Target>::supported_formats(target.device.renderer())
} else {
Bind::<Target>::supported_formats(self.render.renderer())
// SAFETY: We know this is safe, because `self.target` can only be `None` if R == T.
let renderer = unsafe {
std::mem::transmute::<&<R::Device as ApiDevice>::Renderer, &<T::Device as ApiDevice>::Renderer>(
self.render.renderer(),
)
};
Bind::<Target>::supported_formats(renderer)
}
}
}
Expand All @@ -1058,7 +1125,7 @@ where
{
type Error = Error<R, T>;
type TextureId = MultiTexture;
type Framebuffer<'buffer> = MultiFramebuffer<'buffer, R, T>;
type Framebuffer<'buffer> = MultiFramebuffer<'buffer, T>;
type Frame<'frame, 'buffer>
= MultiFrame<'render, 'target, 'frame, 'buffer, R, T>
where
Expand Down Expand Up @@ -1195,11 +1262,19 @@ where
let mut target = None;
let mut new_framebuffer = None;
let frame = match &mut framebuffer.0 {
MultiFramebufferInternal::Render(framebuffer) => self
.render
.renderer_mut()
.render(framebuffer, size, dst_transform)
.map_err(Error::Render)?,
MultiFramebufferInternal::Render(framebuffer) => {
// SAFETY: We know this is fine, because target can only be `None` (and thus this framebuffer be of variant `Render`), if R == T.
let framebuffer = unsafe {
std::mem::transmute::<
&mut <<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'buffer>,
&mut <<R::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'buffer>,
>(framebuffer)
};
self.render
.renderer_mut()
.render(framebuffer, size, dst_transform)
.map_err(Error::Render)?
}
MultiFramebufferInternal::Target(target_framebuffer) => {
let (target_device, render_framebuffer, texture, format) = target_state.unwrap();
target = Some(TargetFrameData {
Expand Down Expand Up @@ -2759,7 +2834,7 @@ where
#[profiling::function]
fn copy_framebuffer(
&mut self,
framebuffer: &MultiFramebuffer<'_, R, T>,
framebuffer: &MultiFramebuffer<'_, T>,
region: Rectangle<i32, BufferCoords>,
format: Fourcc,
) -> Result<Self::TextureMapping, <Self as RendererSuper>::Error> {
Expand All @@ -2773,12 +2848,20 @@ where
.map(|mapping| MultiTextureMapping(TextureMappingInternal::Either(mapping)))
.map_err(Error::Target)
}
MultiFramebufferInternal::Render(fb) => self
.render
.renderer_mut()
.copy_framebuffer(fb, region, format)
.map(|mapping| MultiTextureMapping(TextureMappingInternal::Or(mapping)))
.map_err(Error::Render),
MultiFramebufferInternal::Render(fb) => {
// SAFETY: We know this is fine, because target can only be `None` (and thus this framebuffer be of variant `Render`), if R == T.
let fb = unsafe {
std::mem::transmute::<
&<<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'_>,
&<<R::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'_>,
>(fb)
};
self.render
.renderer_mut()
.copy_framebuffer(fb, region, format)
.map(|mapping| MultiTextureMapping(TextureMappingInternal::Or(mapping)))
.map_err(Error::Render)
}
}
}

Expand Down Expand Up @@ -2834,7 +2917,7 @@ where
}
}

impl<'frame, 'buffer, R: GraphicsApi, T: GraphicsApi> BlitFrame<MultiFramebuffer<'buffer, R, T>>
impl<'frame, 'buffer, R: GraphicsApi, T: GraphicsApi> BlitFrame<MultiFramebuffer<'buffer, T>>
for MultiFrame<'_, '_, 'frame, 'buffer, R, T>
where
<<R::Device as ApiDevice>::Renderer as RendererSuper>::Frame<'frame, 'buffer>:
Expand All @@ -2853,7 +2936,7 @@ where
#[profiling::function]
fn blit_to(
&mut self,
to: &mut MultiFramebuffer<'buffer, R, T>,
to: &mut MultiFramebuffer<'buffer, T>,
src: Rectangle<i32, Physical>,
dst: Rectangle<i32, Physical>,
filter: TextureFilter,
Expand All @@ -2874,6 +2957,13 @@ where
let MultiFramebufferInternal::Render(ref mut to_fb) = &mut to.0 else {
unreachable!()
};
// SAFETY: We know this is fine, because target can only be `None` (and thus this framebuffer be of variant `Render`), if R == T.
let to_fb = unsafe {
std::mem::transmute::<
&mut <<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'_>,
&mut <<R::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'_>,
>(to_fb)
};
self.frame
.as_mut()
.unwrap()
Expand All @@ -2886,7 +2976,7 @@ where
#[profiling::function]
fn blit_from(
&mut self,
from: &MultiFramebuffer<'buffer, R, T>,
from: &MultiFramebuffer<'buffer, T>,
src: Rectangle<i32, Physical>,
dst: Rectangle<i32, Physical>,
filter: TextureFilter,
Expand All @@ -2907,6 +2997,13 @@ where
let MultiFramebufferInternal::Render(ref from_fb) = &from.0 else {
unreachable!()
};
// SAFETY: We know this is fine, because target can only be `None` (and thus this framebuffer be of variant `Render`), if R == T.
let from_fb = unsafe {
std::mem::transmute::<
&<<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'_>,
&<<R::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'_>,
>(from_fb)
};
self.frame
.as_mut()
.unwrap()
Expand Down Expand Up @@ -2934,8 +3031,8 @@ where
#[profiling::function]
fn blit(
&mut self,
from: &MultiFramebuffer<'_, R, T>,
to: &mut MultiFramebuffer<'_, R, T>,
from: &MultiFramebuffer<'_, T>,
to: &mut MultiFramebuffer<'_, T>,
src: Rectangle<i32, Physical>,
dst: Rectangle<i32, Physical>,
filter: TextureFilter,
Expand All @@ -2959,6 +3056,20 @@ where
let MultiFramebufferInternal::Render(ref mut to_fb) = &mut to.0 else {
unreachable!()
};
// SAFETY: We know this is fine, because target can only be `None` (and thus this framebuffer be of variant `Render`), if R == T.
let from_fb = unsafe {
std::mem::transmute::<
&<<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'_>,
&<<R::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'_>,
>(from_fb)
};
// SAFETY: We know this is fine, because target can only be `None` (and thus this framebuffer be of variant `Render`), if R == T.
let to_fb = unsafe {
std::mem::transmute::<
&mut <<T::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'_>,
&mut <<R::Device as ApiDevice>::Renderer as RendererSuper>::Framebuffer<'_>,
>(to_fb)
};
self.render
.renderer_mut()
.blit(from_fb, to_fb, src, dst, filter)
Expand Down
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