fyrox_impl/renderer/

mod.rs

// Copyright (c) 2019-present Dmitry Stepanov and Fyrox Engine contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

//! Renderer is a "workhorse" of the engine, it draws scenes (both 3D and 2D), user interface,
//! debug geometry and can add user-defined render passes. Current renderer implementation is not
//! very flexible, but should cover 95% of use cases.

#![warn(missing_docs)]

pub mod framework;

pub mod bundle;
pub mod cache;
pub mod debug_renderer;
pub mod observer;
pub mod resources;
pub mod stats;
pub mod storage;
pub mod ui_renderer;
pub mod utils;
pub mod visibility;

mod bloom;
mod convolution;
mod fxaa;
mod gbuffer;
mod hdr;
mod light;
mod light_volume;
mod occlusion;
mod settings;
mod shadow;
mod ssao;

use crate::renderer::hdr::HdrRendererArgs;
use crate::{
    asset::{event::ResourceEvent, manager::ResourceManager},
    core::{
        algebra::{Matrix4, Vector2, Vector3},
        color::Color,
        info,
        log::{Log, MessageKind},
        math::Rect,
        pool::Handle,
        sstorage::ImmutableString,
    },
    engine::error::EngineError,
    graphics::{
        error::FrameworkError,
        framebuffer::{Attachment, DrawCallStatistics, GpuFrameBuffer},
        gpu_texture::{GpuTexture, GpuTextureDescriptor, GpuTextureKind, PixelKind},
        server::{GraphicsServer, SharedGraphicsServer},
        PolygonFace, PolygonFillMode,
    },
    material::shader::Shader,
    renderer::{
        bundle::{BundleRenderContext, RenderDataBundleStorage, RenderDataBundleStorageOptions},
        cache::texture::convert_pixel_kind,
        cache::{
            geometry::GeometryCache,
            shader::{
                binding, property, PropertyGroup, RenderMaterial, RenderPassContainer, ShaderCache,
            },
            texture::TextureCache,
            uniform::{UniformBufferCache, UniformMemoryAllocator},
        },
        convolution::{EnvironmentMapIrradianceConvolution, EnvironmentMapSpecularConvolution},
        debug_renderer::DebugRenderer,
        fxaa::FxaaRenderer,
        gbuffer::{GBuffer, GBufferRenderContext},
        hdr::HighDynamicRangeRenderer,
        light::{DeferredLightRenderer, DeferredRendererContext},
        ssao::ScreenSpaceAmbientOcclusionRenderer,
        ui_renderer::UiRenderInfo,
        ui_renderer::{UiRenderContext, UiRenderer},
        visibility::VisibilityCache,
    },
    resource::texture::{Texture, TextureKind, TextureResource},
    scene::{mesh::RenderPath, node::Node, Scene, SceneContainer},
};
use cache::DynamicSurfaceCache;
use fxhash::FxHashMap;
use fyrox_graph::SceneGraph;
use observer::{Observer, ObserversCollection};
use resources::RendererResources;
pub use settings::*;
pub use stats::*;
use std::sync::LazyLock;
use std::{
    any::{Any, TypeId},
    cell::RefCell,
    collections::hash_map::Entry,
    rc::Rc,
    sync::mpsc::Receiver,
};
use winit::window::Window;

static GBUFFER_PASS_NAME: LazyLock<ImmutableString> =
    LazyLock::new(|| ImmutableString::new("GBuffer"));

static DIRECTIONAL_SHADOW_PASS_NAME: LazyLock<ImmutableString> =
    LazyLock::new(|| ImmutableString::new("DirectionalShadow"));

static SPOT_SHADOW_PASS_NAME: LazyLock<ImmutableString> =
    LazyLock::new(|| ImmutableString::new("SpotShadow"));

static POINT_SHADOW_PASS_NAME: LazyLock<ImmutableString> =
    LazyLock::new(|| ImmutableString::new("PointShadow"));

/// Checks whether the provided render pass name is one of the names of built-in shadow render passes.
pub fn is_shadow_pass(render_pass_name: &str) -> bool {
    render_pass_name == &**DIRECTIONAL_SHADOW_PASS_NAME
        || render_pass_name == &**SPOT_SHADOW_PASS_NAME
        || render_pass_name == &**POINT_SHADOW_PASS_NAME
}

/// A set of frame buffers, renderers, that contains scene-specific data.
pub struct SceneRenderData {
    /// A set of render data containers associated with cameras.
    pub camera_data: FxHashMap<Handle<Node>, RenderDataContainer>,
    /// Scene-specific render data.
    pub scene_data: RenderDataContainer,
}

impl SceneRenderData {
    /// Creates new scene-specific render data.
    pub fn new(
        server: &dyn GraphicsServer,
        frame_size: Vector2<f32>,
        final_frame_texture: FrameTextureKind,
    ) -> Result<Self, FrameworkError> {
        Ok(Self {
            camera_data: Default::default(),
            scene_data: RenderDataContainer::new(server, frame_size, final_frame_texture)?,
        })
    }

    /// Sets the new quality settings.
    pub fn set_quality_settings(&mut self, settings: &QualitySettings) {
        for camera_data in self.camera_data.values_mut() {
            camera_data.set_quality_settings(settings);
        }
        self.scene_data.set_quality_settings(settings);
    }
}

fn recreate_render_data_if_needed<T: Any>(
    parent: Handle<T>,
    server: &dyn GraphicsServer,
    data: &mut RenderDataContainer,
    frame_size: Vector2<f32>,
    final_frame_texture: FrameTextureKind,
) -> Result<(), FrameworkError> {
    if data.gbuffer.width != frame_size.x as i32 || data.gbuffer.height != frame_size.y as i32 {
        Log::info(format!(
            "Associated scene rendering data was re-created for {} ({}), because render \
                 frame size was changed. Old is {}x{}, new {}x{}!",
            parent,
            std::any::type_name::<T>(),
            data.gbuffer.width,
            data.gbuffer.height,
            frame_size.x,
            frame_size.y
        ));

        *data = RenderDataContainer::new(server, frame_size, final_frame_texture)?;
    }

    Ok(())
}

/// A set of frame buffers and renderers that can be used to render to.
pub struct RenderDataContainer {
    /// Prefiltered environment map that contains a specular component of the environment map with
    /// roughness encoded in mip levels.
    pub environment_map_specular_convolution: Option<EnvironmentMapSpecularConvolution>,

    /// Irradiance cube map. Contains computed the irradiance computed from the environment map.
    pub environment_map_irradiance_convolution: EnvironmentMapIrradianceConvolution,

    /// A flag that defines whether the renderer must recalculate specular/irradiance convolution
    /// for environment maps.
    pub need_recalculate_convolution: bool,

    /// Screen space ambient occlusion renderer.
    pub ssao_renderer: ScreenSpaceAmbientOcclusionRenderer,

    /// G-Buffer of the container.
    pub gbuffer: GBuffer,

    /// Intermediate high dynamic range frame buffer.
    pub hdr_scene_framebuffer: GpuFrameBuffer,

    /// Final frame of the container. Tone mapped + gamma corrected.
    pub ldr_scene_framebuffer: GpuFrameBuffer,

    /// Additional frame buffer for post-processing.
    pub ldr_temp_framebuffer: [GpuFrameBuffer; 2],

    /// HDR renderer has to be created per container, because it contains
    /// scene luminance.
    pub hdr_renderer: HighDynamicRangeRenderer,

    /// Rendering statistics for a container.
    pub statistics: SceneStatistics,
}

/// Texture kind that will be used to store final frame image.
#[derive(Default)]
pub enum FrameTextureKind {
    /// Rectangular texture.
    #[default]
    Rectangle,
    /// Cube texture (six square textures). Used primarily for reflection probes.
    Cube,
}

impl RenderDataContainer {
    /// Creates a new container.
    pub fn new(
        server: &dyn GraphicsServer,
        frame_size: Vector2<f32>,
        final_frame_texture: FrameTextureKind,
    ) -> Result<Self, FrameworkError> {
        let width = frame_size.x as usize;
        let height = frame_size.y as usize;

        if matches!(final_frame_texture, FrameTextureKind::Cube) {
            assert_eq!(width, height);
        }

        let depth_stencil = server.create_2d_render_target(
            "ObserverDepthStencil",
            PixelKind::D24S8,
            width,
            height,
        )?;
        // Intermediate scene frame will be rendered in HDR render target.
        let hdr_frame_texture = server.create_2d_render_target(
            "ObserverHdrFrame",
            PixelKind::RGBA16F,
            width,
            height,
        )?;

        let hdr_scene_framebuffer = server.create_frame_buffer(
            Some(Attachment::depth_stencil(depth_stencil.clone())),
            vec![Attachment::color(hdr_frame_texture)],
        )?;

        let ldr_frame_texture = server.create_texture(GpuTextureDescriptor {
            name: "LdrFrameTexture",
            kind: match final_frame_texture {
                FrameTextureKind::Rectangle => GpuTextureKind::Rectangle { width, height },
                FrameTextureKind::Cube => GpuTextureKind::Cube { size: width },
            },
            // Final scene frame is in standard sRGB space.
            pixel_kind: PixelKind::RGBA8,
            ..Default::default()
        })?;

        let ldr_scene_framebuffer = server.create_frame_buffer(
            Some(Attachment::depth_stencil(depth_stencil.clone())),
            vec![Attachment::color(ldr_frame_texture)],
        )?;

        fn make_ldr_temp_frame_buffer(
            server: &dyn GraphicsServer,
            width: usize,
            height: usize,
            depth_stencil: GpuTexture,
        ) -> Result<GpuFrameBuffer, FrameworkError> {
            let ldr_temp_texture = server.create_texture(GpuTextureDescriptor {
                name: "LdrTempTexture",
                kind: GpuTextureKind::Rectangle { width, height },
                // Final scene frame is in standard sRGB space.
                pixel_kind: PixelKind::RGBA8,
                ..Default::default()
            })?;

            server.create_frame_buffer(
                Some(Attachment::depth_stencil(depth_stencil)),
                vec![Attachment::color(ldr_temp_texture)],
            )
        }

        Ok(Self {
            need_recalculate_convolution: true,
            environment_map_specular_convolution: Default::default(),
            environment_map_irradiance_convolution: EnvironmentMapIrradianceConvolution::new(
                server, 32,
            )?,
            ssao_renderer: ScreenSpaceAmbientOcclusionRenderer::new(server, width, height)?,
            gbuffer: GBuffer::new(server, width, height)?,
            hdr_renderer: HighDynamicRangeRenderer::new(width, height, server)?,
            hdr_scene_framebuffer,
            ldr_scene_framebuffer,
            ldr_temp_framebuffer: [
                make_ldr_temp_frame_buffer(server, width, height, depth_stencil.clone())?,
                make_ldr_temp_frame_buffer(server, width, height, depth_stencil.clone())?,
            ],
            statistics: Default::default(),
        })
    }

    fn copy_depth_stencil_to_scene_framebuffer(&mut self) {
        self.gbuffer.framebuffer().blit_to(
            &self.hdr_scene_framebuffer,
            0,
            0,
            self.gbuffer.width,
            self.gbuffer.height,
            0,
            0,
            self.gbuffer.width,
            self.gbuffer.height,
            false,
            true,
            true,
        );
    }

    /// Returns high-dynamic range frame buffer texture.
    pub fn hdr_scene_frame_texture(&self) -> &GpuTexture {
        &self.hdr_scene_framebuffer.color_attachments()[0].texture
    }

    /// Returns low-dynamic range frame buffer texture (final frame).
    pub fn ldr_scene_frame_texture(&self) -> &GpuTexture {
        &self.ldr_scene_framebuffer.color_attachments()[0].texture
    }

    /// Returns low-dynamic range frame buffer texture (accumulation frame).
    pub fn ldr_temp_frame_texture(&self, i: usize) -> &GpuTexture {
        &self.ldr_temp_framebuffer[i].color_attachments()[0].texture
    }

    /// Sets the new quality settings.
    pub fn set_quality_settings(&mut self, settings: &QualitySettings) {
        self.ssao_renderer.set_radius(settings.ssao_radius);
    }
}

/// Creates a view-projection matrix that projects unit quad a screen with the specified viewport.
pub fn make_viewport_matrix(viewport: Rect<i32>) -> Matrix4<f32> {
    Matrix4::new_orthographic(
        0.0,
        viewport.w() as f32,
        viewport.h() as f32,
        0.0,
        -1.0,
        1.0,
    ) * Matrix4::new_nonuniform_scaling(&Vector3::new(
        viewport.w() as f32,
        viewport.h() as f32,
        0.0,
    ))
}

/// See module docs.
pub struct Renderer {
    backbuffer: GpuFrameBuffer,
    scene_render_passes: Vec<Rc<RefCell<dyn SceneRenderPass>>>,
    deferred_light_renderer: DeferredLightRenderer,
    /// A set of textures of certain kinds that could be used as a stub in cases when you don't have
    /// your own texture of this kind.
    pub renderer_resources: RendererResources,
    /// User interface renderer.
    pub ui_renderer: UiRenderer,
    statistics: Statistics,
    frame_size: (u32, u32),
    quality_settings: QualitySettings,
    /// Debug renderer instance can be used for debugging purposes
    pub debug_renderer: DebugRenderer,
    /// Screen space debug renderer instance can be used for debugging purposes to draw lines directly
    /// on screen. It is useful to debug some rendering algorithms.
    pub screen_space_debug_renderer: DebugRenderer,
    /// A set of associated data for each scene that was rendered.
    pub scene_data_map: FxHashMap<Handle<Scene>, SceneRenderData>,
    backbuffer_clear_color: Color,
    /// Texture cache with GPU textures.
    pub texture_cache: TextureCache,
    /// Uniform buffer cache.
    pub uniform_buffer_cache: UniformBufferCache,
    shader_cache: ShaderCache,
    geometry_cache: GeometryCache,
    fxaa_renderer: FxaaRenderer,
    texture_event_receiver: Receiver<ResourceEvent>,
    shader_event_receiver: Receiver<ResourceEvent>,
    /// TextureId -> FrameBuffer mapping. This mapping is used for temporal frame buffers
    /// like ones used to render UI instances.
    pub ui_frame_buffers: FxHashMap<u64, GpuFrameBuffer>,
    uniform_memory_allocator: UniformMemoryAllocator,
    /// Dynamic surface cache. See [`DynamicSurfaceCache`] docs for more info.
    pub dynamic_surface_cache: DynamicSurfaceCache,
    /// Visibility cache based on occlusion query.
    pub visibility_cache: VisibilityCache,
    /// Graphics server.
    pub server: SharedGraphicsServer,
}

fn make_ui_frame_buffer(
    frame_size: Vector2<f32>,
    server: &dyn GraphicsServer,
    pixel_kind: PixelKind,
) -> Result<GpuFrameBuffer, FrameworkError> {
    let color_texture = server.create_texture(GpuTextureDescriptor {
        name: "UiFbTexture",
        kind: GpuTextureKind::Rectangle {
            width: frame_size.x as usize,
            height: frame_size.y as usize,
        },
        pixel_kind,
        ..Default::default()
    })?;

    let depth_stencil = server.create_2d_render_target(
        "UiDepthStencil",
        PixelKind::D24S8,
        frame_size.x as usize,
        frame_size.y as usize,
    )?;

    server.create_frame_buffer(
        Some(Attachment::depth_stencil(depth_stencil)),
        vec![Attachment::color(color_texture)],
    )
}

/// A context for custom scene render passes.
pub struct SceneRenderPassContext<'a, 'b> {
    /// Amount of time (in seconds) that passed from creation of the engine. Keep in mind, that
    /// this value is **not** guaranteed to match real time. A user can change delta time with
    /// which the engine "ticks" and this delta time affects elapsed time.
    pub elapsed_time: f32,
    /// A graphics server that is used as a wrapper to underlying graphics API.
    pub server: &'a dyn GraphicsServer,

    /// A texture cache that uploads engine's `Texture` as internal `GpuTexture` to GPU.
    /// Use this to get a corresponding GPU texture by an instance of a `Texture`.
    pub texture_cache: &'a mut TextureCache,

    /// A geometry cache that uploads engine's `SurfaceData` as internal `GeometryBuffer` to GPU.
    /// Use this to get a corresponding GPU geometry buffer (essentially it is just a VAO) by an
    /// instance of a `SurfaceData`.
    pub geometry_cache: &'a mut GeometryCache,

    /// A cache that stores all native shaders associated with a shader resource. You can use it
    /// to get a ready-to-use set of shaders for your shader resource, which could be obtained
    /// from a material.
    pub shader_cache: &'a mut ShaderCache,

    /// A storage that contains "pre-compiled" groups of render data (batches).
    pub bundle_storage: &'a RenderDataBundleStorage,

    /// Current quality settings of the renderer.
    pub quality_settings: &'a QualitySettings,

    /// Current framebuffer to which scene is being rendered to.
    pub framebuffer: &'a GpuFrameBuffer,

    /// A scene being rendered.
    pub scene: &'b Scene,

    /// A camera from the scene that is used as "eyes".
    pub observer: &'b Observer,

    /// A handle of the scene being rendered.
    pub scene_handle: Handle<Scene>,

    /// A set of textures of certain kinds that could be used as a stub in cases when you don't have
    /// your own texture of this kind.
    pub renderer_resources: &'a RendererResources,

    /// A texture with depth values from G-Buffer.
    ///
    /// # Important notes
    ///
    /// Keep in mind that G-Buffer cannot be modified in custom render passes, so you don't
    /// have an ability to write to this texture. However, you can still write to depth of
    /// the frame buffer as you'd normally do.
    pub depth_texture: &'a GpuTexture,

    /// A texture with world-space normals from G-Buffer.
    ///
    /// # Important notes
    ///
    /// Keep in mind that G-Buffer cannot be modified in custom render passes, so you don't
    /// have an ability to write to this texture.
    pub normal_texture: &'a GpuTexture,

    /// A texture with ambient lighting values from G-Buffer.
    ///
    /// # Important notes
    ///
    /// Keep in mind that G-Buffer cannot be modified in custom render passes, so you don't
    /// have an ability to write to this texture.
    pub ambient_texture: &'a GpuTexture,

    /// User interface renderer.
    pub ui_renderer: &'a mut UiRenderer,

    /// A cache of uniform buffers.
    pub uniform_buffer_cache: &'a mut UniformBufferCache,

    /// Memory allocator for uniform buffers that tries to pack uniforms densely into large uniform
    /// buffers, giving you offsets to the data.
    pub uniform_memory_allocator: &'a mut UniformMemoryAllocator,

    /// Dynamic surface cache. See [`DynamicSurfaceCache`] docs for more info.
    pub dynamic_surface_cache: &'a mut DynamicSurfaceCache,

    /// A reference to the resource manager.
    pub resource_manager: &'a ResourceManager,
}

/// A trait for custom scene rendering pass. It could be used to add your own rendering techniques.
pub trait SceneRenderPass {
    /// Renders scene into high dynamic range target. It will be called for **each** scene
    /// registered in the engine, but you are able to filter out scene by its handle.
    fn on_hdr_render(
        &mut self,
        _ctx: SceneRenderPassContext,
    ) -> Result<RenderPassStatistics, FrameworkError> {
        Ok(RenderPassStatistics::default())
    }

    /// Renders scene into low dynamic range target. It will be called for **each** scene
    /// registered in the engine, but you are able to filter out scene by its handle.
    fn on_ldr_render(
        &mut self,
        _ctx: SceneRenderPassContext,
    ) -> Result<RenderPassStatistics, FrameworkError> {
        Ok(RenderPassStatistics::default())
    }

    /// Should return type id of a plugin, that holds this render pass. **WARNING:** Setting incorrect
    /// (anything else, than a real plugin's type id) value here will result in hard crash with happy
    /// debugging times.
    fn source_type_id(&self) -> TypeId;
}

fn blit_pixels(
    uniform_buffer_cache: &mut UniformBufferCache,
    framebuffer: &GpuFrameBuffer,
    texture: &GpuTexture,
    blit_shader: &RenderPassContainer,
    viewport: Rect<i32>,
    renderer_resources: &RendererResources,
) -> Result<DrawCallStatistics, FrameworkError> {
    let wvp = make_viewport_matrix(viewport);
    let properties = PropertyGroup::from([property("worldViewProjection", &wvp)]);
    let material = RenderMaterial::from([
        binding(
            "diffuseTexture",
            (texture, &renderer_resources.linear_clamp_sampler),
        ),
        binding("properties", &properties),
    ]);
    blit_shader.run_pass(
        1,
        &ImmutableString::new("Primary"),
        framebuffer,
        &renderer_resources.quad,
        viewport,
        &material,
        uniform_buffer_cache,
        Default::default(),
        None,
    )
}

fn render_target_size(
    render_target: &TextureResource,
) -> Result<(Vector2<f32>, FrameTextureKind), FrameworkError> {
    render_target
        .data_ref()
        .as_loaded_ref()
        .and_then(|rt| match rt.kind() {
            TextureKind::Rectangle { width, height } => Some((
                Vector2::new(width as f32, height as f32),
                FrameTextureKind::Rectangle,
            )),
            TextureKind::Cube { size } => Some((
                Vector2::new(size as f32, size as f32),
                FrameTextureKind::Cube,
            )),
            _ => None,
        })
        .ok_or_else(|| {
            FrameworkError::Custom(
                "Render target must be a valid rectangle or cube texture!".to_string(),
            )
        })
}

impl Renderer {
    /// Creates a new renderer with the given graphics server.
    pub fn new(
        server: Rc<dyn GraphicsServer>,
        frame_size: (u32, u32),
        resource_manager: &ResourceManager,
    ) -> Result<Self, EngineError> {
        let settings = QualitySettings::default();

        let (texture_event_sender, texture_event_receiver) = std::sync::mpsc::channel();

        resource_manager
            .state()
            .event_broadcaster
            .add(texture_event_sender);

        let (shader_event_sender, shader_event_receiver) = std::sync::mpsc::channel();

        resource_manager
            .state()
            .event_broadcaster
            .add(shader_event_sender);

        let caps = server.capabilities();
        Log::info(format!("Graphics Server Capabilities\n{caps:?}",));

        let shader_cache = ShaderCache::default();

        let one_megabyte = 1024 * 1024;
        let uniform_memory_allocator = UniformMemoryAllocator::new(
            // Clamp max uniform block size from the upper bound, to prevent allocating huge
            // uniform buffers when GPU supports it. Some AMD GPUs are able to allocate ~500 Mb
            // uniform buffers, which will lead to ridiculous VRAM consumption.
            caps.max_uniform_block_size.min(one_megabyte),
            caps.uniform_buffer_offset_alignment,
        );

        Ok(Self {
            backbuffer: server.back_buffer(),
            frame_size,
            deferred_light_renderer: DeferredLightRenderer::new(&*server, &settings)?,
            renderer_resources: RendererResources::new(&*server)?,
            ui_renderer: UiRenderer::new(&*server)?,
            quality_settings: settings,
            debug_renderer: DebugRenderer::new(&*server)?,
            screen_space_debug_renderer: DebugRenderer::new(&*server)?,
            scene_data_map: Default::default(),
            backbuffer_clear_color: Color::BLACK,
            texture_cache: Default::default(),
            geometry_cache: Default::default(),
            ui_frame_buffers: Default::default(),
            fxaa_renderer: FxaaRenderer::default(),
            statistics: Statistics::default(),
            shader_event_receiver,
            texture_event_receiver,
            shader_cache,
            scene_render_passes: Default::default(),
            uniform_buffer_cache: UniformBufferCache::new(server.clone()),
            server,
            visibility_cache: Default::default(),
            uniform_memory_allocator,
            dynamic_surface_cache: DynamicSurfaceCache::new(),
        })
    }

    /// Adds a custom render pass.
    pub fn add_render_pass(&mut self, pass: Rc<RefCell<dyn SceneRenderPass>>) {
        self.scene_render_passes.push(pass);
    }

    /// Removes specified render pass.
    pub fn remove_render_pass(&mut self, pass: Rc<RefCell<dyn SceneRenderPass>>) {
        if let Some(index) = self
            .scene_render_passes
            .iter()
            .position(|p| Rc::ptr_eq(p, &pass))
        {
            self.scene_render_passes.remove(index);
        }
    }

    /// Returns a slice with every registered render passes.
    pub fn render_passes(&self) -> &[Rc<RefCell<dyn SceneRenderPass>>] {
        &self.scene_render_passes
    }

    /// Removes all render passes from the renderer.
    pub fn clear_render_passes(&mut self) {
        self.scene_render_passes.clear()
    }

    /// Returns statistics for last frame.
    pub fn get_statistics(&self) -> Statistics {
        self.statistics
    }

    /// Unloads texture from GPU memory.
    pub fn unload_texture(&mut self, texture: &TextureResource) {
        self.texture_cache.unload(texture)
    }

    /// Sets color which will be used to fill screen when there is nothing to render.
    pub fn set_backbuffer_clear_color(&mut self, color: Color) {
        self.backbuffer_clear_color = color;
    }

    /// Returns a reference to current graphics server.
    pub fn graphics_server(&self) -> &dyn GraphicsServer {
        &*self.server
    }

    /// Sets new frame size. You should call the same method on [`crate::engine::Engine`]
    /// instead, which will update the size for the user interface and rendering context
    /// as well as this one.
    ///
    /// # Notes
    ///
    /// Input values will be set to 1 pixel if new size is 0. Rendering cannot
    /// be performed into 0x0 texture.
    pub(crate) fn set_frame_size(&mut self, new_size: (u32, u32)) -> Result<(), FrameworkError> {
        self.frame_size.0 = new_size.0.max(1);
        self.frame_size.1 = new_size.1.max(1);

        self.graphics_server().set_frame_size(new_size);

        Ok(())
    }

    /// Returns current (width, height) pair of back buffer size.
    pub fn get_frame_size(&self) -> (u32, u32) {
        self.frame_size
    }

    /// Returns current bounds of back buffer.
    pub fn get_frame_bounds(&self) -> Vector2<f32> {
        Vector2::new(self.frame_size.0 as f32, self.frame_size.1 as f32)
    }

    /// Sets new quality settings for renderer. Never call this method in a loop, otherwise
    /// you may get **significant** lags. Always check if current quality setting differs
    /// from new!
    pub fn set_quality_settings(
        &mut self,
        settings: &QualitySettings,
    ) -> Result<(), FrameworkError> {
        self.quality_settings = *settings;
        for data in self.scene_data_map.values_mut() {
            data.set_quality_settings(settings);
        }
        self.deferred_light_renderer
            .set_quality_settings(&*self.server, settings)
    }

    /// Returns current quality settings.
    pub fn get_quality_settings(&self) -> QualitySettings {
        self.quality_settings
    }

    /// Removes all cached GPU data, forces renderer to re-upload data to GPU.
    /// Do not call this method until you absolutely need! It may cause **significant**
    /// performance lag!
    pub fn flush(&mut self) {
        self.texture_cache.clear();
        self.geometry_cache.clear();
    }

    /// Renders the given UI into specified render target. This method is especially useful if you need
    /// to have off-screen UIs. This method will render the specified UI to the given render target.
    /// If the render target is not specified (set to [`None`]), the UI will be rendered directly on
    /// screen. Keep in mind that ideally, the resolution of the render target should match the screen
    /// size of the UI. Otherwise, the rendered image will have some sort of aliasing issues.
    pub fn render_ui(&mut self, render_info: UiRenderInfo) -> Result<(), FrameworkError> {
        let _debug_scope = self.server.begin_scope(&format!("UI {:p}", render_info.ui));

        let (frame_buffer, rt_size) = if let Some(render_target) =
            render_info.render_target.as_ref()
        {
            let (rt_size, rt_pixel_kind) = render_target
                .data_ref()
                .as_loaded_ref()
                .and_then(|rt| {
                    rt.kind()
                        .rectangle_size()
                        .map(|s| (s.cast::<f32>(), convert_pixel_kind(rt.pixel_kind())))
                })
                .ok_or_else(|| FrameworkError::Custom("invalid render target state".to_string()))?;

            // Create or reuse existing frame buffer.
            let frame_buffer = match self.ui_frame_buffers.entry(render_target.key()) {
                Entry::Occupied(entry) => {
                    let frame_buffer = entry.into_mut();
                    let frame = frame_buffer.color_attachments().first().unwrap();
                    let color_texture_kind = frame.texture.kind();
                    if let GpuTextureKind::Rectangle { width, height } = color_texture_kind {
                        if width != rt_size.x as usize
                            || height != rt_size.y as usize
                            || frame.texture.pixel_kind() != rt_pixel_kind
                        {
                            *frame_buffer =
                                make_ui_frame_buffer(rt_size, &*self.server, rt_pixel_kind)?;
                        }
                    } else {
                        return Err(FrameworkError::Custom(
                            "ui can be rendered only in rectangle texture!".to_string(),
                        ));
                    }
                    frame_buffer
                }
                Entry::Vacant(entry) => {
                    entry.insert(make_ui_frame_buffer(rt_size, &*self.server, rt_pixel_kind)?)
                }
            };

            let viewport = Rect::new(0, 0, rt_size.x as i32, rt_size.y as i32);
            frame_buffer.clear(viewport, Some(render_info.clear_color), Some(0.0), Some(0));

            (frame_buffer, rt_size)
        } else {
            (
                &mut self.backbuffer,
                Vector2::new(self.frame_size.0 as f32, self.frame_size.1 as f32),
            )
        };

        self.statistics += self.ui_renderer.render(UiRenderContext {
            server: &*self.server,
            viewport: Rect::new(0, 0, rt_size.x as i32, rt_size.y as i32),
            frame_buffer,
            frame_width: rt_size.x,
            frame_height: rt_size.y,
            drawing_context: &render_info.ui.drawing_context,
            renderer_resources: &self.renderer_resources,
            texture_cache: &mut self.texture_cache,
            uniform_buffer_cache: &mut self.uniform_buffer_cache,
            render_pass_cache: &mut self.shader_cache,
            uniform_memory_allocator: &mut self.uniform_memory_allocator,
            resource_manager: render_info.resource_manager,
        })?;

        if let Some(render_target) = render_info.render_target.as_ref() {
            // Finally, register texture in the cache so it will become available as texture in
            // deferred/forward renderer.
            self.texture_cache.try_register(
                &*self.server,
                render_target,
                frame_buffer
                    .color_attachments()
                    .first()
                    .unwrap()
                    .texture
                    .clone(),
            )?;
        }

        Ok(())
    }

    fn update_texture_cache(&mut self, resource_manager: &ResourceManager, dt: f32) {
        // Maximum amount of textures uploaded to GPU per frame. This defines throughput **only** for
        // requests from resource manager. This is needed to prevent huge lag when there are tons of
        // requests, so this is some kind of work load balancer.
        const THROUGHPUT: usize = 5;

        let mut uploaded = 0;
        while let Ok(event) = self.texture_event_receiver.try_recv() {
            if let ResourceEvent::Loaded(resource) | ResourceEvent::Reloaded(resource) = event {
                if let Some(texture) = resource.try_cast::<Texture>() {
                    match self
                        .texture_cache
                        .upload(&*self.server, resource_manager, &texture)
                    {
                        Ok(_) => {
                            uploaded += 1;
                            if uploaded >= THROUGHPUT {
                                break;
                            }
                        }
                        Err(e) => {
                            Log::writeln(
                                MessageKind::Error,
                                format!("Failed to upload texture to GPU. Reason: {e:?}"),
                            );
                        }
                    }
                }
            }
        }

        self.texture_cache.update(dt);
    }

    fn update_shader_cache(&mut self, dt: f32) {
        while let Ok(event) = self.shader_event_receiver.try_recv() {
            if let ResourceEvent::Loaded(resource) | ResourceEvent::Reloaded(resource) = event {
                if let Some(shader) = resource.try_cast::<Shader>() {
                    // Remove and immediately "touch" the shader cache to force upload shader.
                    self.shader_cache.remove(&shader);
                    let _ = self.shader_cache.get(&*self.server, &shader);
                }
            }
        }

        self.shader_cache.update(dt)
    }

    /// Update caches - this will remove timed out resources.
    ///
    /// Normally, this is called from `Engine::update()`.
    /// You should only call this manually if you don't use that method.
    pub fn update_caches(&mut self, resource_manager: &ResourceManager, dt: f32) {
        self.update_texture_cache(resource_manager, dt);
        self.update_shader_cache(dt);
        self.geometry_cache.update(dt);
    }

    fn render_scene_observer(
        &mut self,
        observer: &Observer,
        scene_handle: Handle<Scene>,
        scene: &Scene,
        elapsed_time: f32,
        dt: f32,
        resource_manager: &ResourceManager,
        need_recalculate_convolution: bool,
    ) -> Result<&mut RenderDataContainer, FrameworkError> {
        let server = &*self.server;

        let scene_render_data = self.scene_data_map.get_mut(&scene_handle).ok_or_else(|| {
            FrameworkError::Custom(format!(
                "No associated render data for {scene_handle} scene!"
            ))
        })?;
        let render_data = if let Some(render_target) = observer.render_target.as_ref() {
            let (rt_size, final_frame_texture) = render_target_size(render_target)?;
            let observer_render_data = match scene_render_data.camera_data.entry(observer.handle) {
                Entry::Occupied(entry) => {
                    let observer_render_data = entry.into_mut();
                    recreate_render_data_if_needed(
                        scene_handle,
                        server,
                        observer_render_data,
                        rt_size,
                        final_frame_texture,
                    )?;
                    observer_render_data
                }
                Entry::Vacant(entry) => {
                    let render_data = entry.insert(RenderDataContainer::new(
                        server,
                        rt_size,
                        final_frame_texture,
                    )?);
                    info!(
                        "A new associated scene rendering data was created for observer {}!",
                        observer.handle
                    );
                    render_data
                }
            };

            if let Some(probe_data) = observer.reflection_probe_data.as_ref() {
                observer_render_data.ldr_scene_framebuffer.set_cubemap_face(
                    0,
                    probe_data.cube_map_face,
                    0,
                );
            }

            self.texture_cache.try_register(
                server,
                render_target,
                observer_render_data.ldr_scene_frame_texture().clone(),
            )?;

            observer_render_data
        } else {
            &mut scene_render_data.scene_data
        };

        render_data.need_recalculate_convolution |= need_recalculate_convolution;

        let visibility_cache = self
            .visibility_cache
            .get_or_register(&scene.graph, observer.handle);

        let mut bundle_storage = RenderDataBundleStorage::from_graph(
            &scene.graph,
            observer.render_mask,
            elapsed_time,
            &observer.position,
            GBUFFER_PASS_NAME.clone(),
            RenderDataBundleStorageOptions {
                collect_lights: true,
            },
            &mut self.dynamic_surface_cache,
        );
        if observer.reflection_probe_data.is_some() {
            bundle_storage.environment_map = None;
        }

        server.set_polygon_fill_mode(
            PolygonFace::FrontAndBack,
            scene.rendering_options.polygon_rasterization_mode,
        );

        render_data.statistics += render_data.gbuffer.fill(GBufferRenderContext {
            server,
            observer,
            geom_cache: &mut self.geometry_cache,
            bundle_storage: &bundle_storage,
            texture_cache: &mut self.texture_cache,
            shader_cache: &mut self.shader_cache,
            quality_settings: &self.quality_settings,
            renderer_resources: &self.renderer_resources,
            graph: &scene.graph,
            uniform_buffer_cache: &mut self.uniform_buffer_cache,
            uniform_memory_allocator: &mut self.uniform_memory_allocator,
            screen_space_debug_renderer: &mut self.screen_space_debug_renderer,
            resource_manager,
        })?;

        server.set_polygon_fill_mode(PolygonFace::FrontAndBack, PolygonFillMode::Fill);

        render_data.copy_depth_stencil_to_scene_framebuffer();

        render_data.hdr_scene_framebuffer.clear(
            observer.viewport,
            Some(
                scene
                    .rendering_options
                    .clear_color
                    .unwrap_or(self.backbuffer_clear_color),
            ),
            None, // Keep depth, we've just copied valid data in it.
            Some(0),
        );

        let (pass_stats, light_stats) =
            self.deferred_light_renderer
                .render(DeferredRendererContext {
                    elapsed_time,
                    server,
                    scene,
                    observer,
                    gbuffer: &mut render_data.gbuffer,
                    ambient_color: match observer.reflection_probe_data.as_ref() {
                        None => scene.rendering_options.ambient_lighting_color,
                        Some(probe_data) => probe_data.ambient_lighting_color,
                    },
                    environment_lighting_source: match observer.reflection_probe_data.as_ref() {
                        None => scene.rendering_options.environment_lighting_source,
                        Some(probe_data) => probe_data.environment_lighting_source,
                    },
                    render_data_bundle: &bundle_storage,
                    settings: &self.quality_settings,
                    textures: &mut self.texture_cache,
                    geometry_cache: &mut self.geometry_cache,
                    frame_buffer: &render_data.hdr_scene_framebuffer,
                    shader_cache: &mut self.shader_cache,
                    renderer_resources: &self.renderer_resources,
                    uniform_buffer_cache: &mut self.uniform_buffer_cache,
                    visibility_cache,
                    uniform_memory_allocator: &mut self.uniform_memory_allocator,
                    dynamic_surface_cache: &mut self.dynamic_surface_cache,
                    ssao_renderer: &render_data.ssao_renderer,
                    resource_manager,
                    environment_map_specular_convolution: &mut render_data
                        .environment_map_specular_convolution,
                    environment_map_irradiance_convolution: &render_data
                        .environment_map_irradiance_convolution,
                    need_recalculate_convolution: &mut render_data.need_recalculate_convolution,
                })?;

        render_data.statistics += light_stats;
        render_data.statistics += pass_stats;

        let depth = render_data.gbuffer.depth();

        {
            let _debug_scope = server.begin_scope("ForwardRendering");

            render_data.statistics += bundle_storage.render_to_frame_buffer(
                server,
                &mut self.geometry_cache,
                &mut self.shader_cache,
                |bundle| bundle.render_path == RenderPath::Forward,
                |_| true,
                BundleRenderContext {
                    texture_cache: &mut self.texture_cache,
                    render_pass_name: &ImmutableString::new("Forward"),
                    frame_buffer: &render_data.hdr_scene_framebuffer,
                    viewport: observer.viewport,
                    uniform_memory_allocator: &mut self.uniform_memory_allocator,
                    resource_manager,
                    use_pom: self.quality_settings.use_parallax_mapping,
                    light_position: &Default::default(),
                    renderer_resources: &self.renderer_resources,
                    ambient_light: scene.rendering_options.ambient_lighting_color,
                    scene_depth: Some(depth),
                },
            )?;
        }

        for render_pass in self.scene_render_passes.iter() {
            let _debug_scope = server.begin_scope(&format!(
                "UserRenderPass::on_hdr_render {:p}",
                render_pass.as_ptr()
            ));

            render_data.statistics +=
                render_pass
                    .borrow_mut()
                    .on_hdr_render(SceneRenderPassContext {
                        elapsed_time,
                        server,
                        texture_cache: &mut self.texture_cache,
                        geometry_cache: &mut self.geometry_cache,
                        shader_cache: &mut self.shader_cache,
                        quality_settings: &self.quality_settings,
                        bundle_storage: &bundle_storage,
                        scene,
                        observer,
                        scene_handle,
                        renderer_resources: &self.renderer_resources,
                        depth_texture: render_data.gbuffer.depth(),
                        normal_texture: render_data.gbuffer.normal_texture(),
                        ambient_texture: render_data.gbuffer.ambient_texture(),
                        framebuffer: &render_data.hdr_scene_framebuffer,
                        ui_renderer: &mut self.ui_renderer,
                        uniform_buffer_cache: &mut self.uniform_buffer_cache,
                        uniform_memory_allocator: &mut self.uniform_memory_allocator,
                        dynamic_surface_cache: &mut self.dynamic_surface_cache,
                        resource_manager,
                    })?;
        }

        // Convert high dynamic range frame to low dynamic range (sRGB) with tone mapping and gamma correction.
        let mut dest_buf = 0;
        let mut src_buf = 1;
        render_data.statistics += render_data.hdr_renderer.render(HdrRendererArgs {
            server,
            hdr_scene_frame: render_data.hdr_scene_frame_texture(),
            ldr_framebuffer: &render_data.ldr_temp_framebuffer[dest_buf],
            viewport: observer.viewport,
            speed: observer.hdr_adaptation_speed * dt,
            exposure: observer.exposure,
            color_grading_lut: observer.color_grading_lut.as_ref(),
            use_color_grading: observer.color_grading_enabled,
            texture_cache: &mut self.texture_cache,
            uniform_buffer_cache: &mut self.uniform_buffer_cache,
            renderer_resources: &self.renderer_resources,
            resource_manager,
            settings: &self.quality_settings,
        })?;
        std::mem::swap(&mut dest_buf, &mut src_buf);

        // Apply FXAA if needed.
        if self.quality_settings.fxaa {
            render_data.statistics += self.fxaa_renderer.render(
                server,
                observer.viewport,
                render_data.ldr_temp_frame_texture(src_buf),
                &render_data.ldr_temp_framebuffer[dest_buf],
                &mut self.uniform_buffer_cache,
                &self.renderer_resources,
            )?;
            std::mem::swap(&mut dest_buf, &mut src_buf);
        }

        render_data.statistics += blit_pixels(
            &mut self.uniform_buffer_cache,
            &render_data.ldr_scene_framebuffer,
            render_data.ldr_temp_frame_texture(src_buf),
            &self.renderer_resources.shaders.blit,
            observer.viewport,
            &self.renderer_resources,
        )?;

        // Render debug geometry in the LDR frame buffer.
        self.debug_renderer.set_lines(&scene.drawing_context.lines);
        render_data.statistics += self.debug_renderer.render(
            server,
            &mut self.uniform_buffer_cache,
            observer.viewport,
            &render_data.ldr_scene_framebuffer,
            observer.position.view_projection_matrix,
            &self.renderer_resources,
        )?;

        for render_pass in self.scene_render_passes.iter() {
            let _debug_scope = server.begin_scope(&format!(
                "UserRenderPass::on_ldr_render {:p}",
                render_pass.as_ptr()
            ));

            render_data.statistics +=
                render_pass
                    .borrow_mut()
                    .on_ldr_render(SceneRenderPassContext {
                        elapsed_time,
                        server,
                        texture_cache: &mut self.texture_cache,
                        geometry_cache: &mut self.geometry_cache,
                        shader_cache: &mut self.shader_cache,
                        quality_settings: &self.quality_settings,
                        bundle_storage: &bundle_storage,
                        scene,
                        observer,
                        scene_handle,
                        renderer_resources: &self.renderer_resources,
                        depth_texture: render_data.gbuffer.depth(),
                        normal_texture: render_data.gbuffer.normal_texture(),
                        ambient_texture: render_data.gbuffer.ambient_texture(),
                        framebuffer: &render_data.ldr_scene_framebuffer,
                        ui_renderer: &mut self.ui_renderer,
                        uniform_buffer_cache: &mut self.uniform_buffer_cache,
                        uniform_memory_allocator: &mut self.uniform_memory_allocator,
                        dynamic_surface_cache: &mut self.dynamic_surface_cache,
                        resource_manager,
                    })?;
        }

        Ok(render_data)
    }

    /// Unconditionally renders a scene and returns a reference to a [`RenderDataContainer`] instance
    /// that contains rendered data (including intermediate data, such as G-Buffer content, etc.).
    pub fn render_scene(
        &mut self,
        scene_handle: Handle<Scene>,
        scene: &Scene,
        elapsed_time: f32,
        dt: f32,
        resource_manager: &ResourceManager,
    ) -> Result<&SceneRenderData, FrameworkError> {
        let graph = &scene.graph;

        let _debug_scope = self.server.begin_scope(&format!("Scene {:p}", scene));

        let backbuffer_width = self.frame_size.0 as f32;
        let backbuffer_height = self.frame_size.1 as f32;

        let window_viewport = Rect::new(0, 0, self.frame_size.0 as i32, self.frame_size.1 as i32);

        let frame_size = scene
            .rendering_options
            .render_target
            .as_ref()
            .map_or_else(
                // Use either backbuffer size
                || Vector2::new(backbuffer_width, backbuffer_height),
                // Or framebuffer size
                |rt| {
                    if let TextureKind::Rectangle { width, height } = rt.data_ref().kind() {
                        Vector2::new(width as f32, height as f32)
                    } else {
                        panic!("only rectangle textures can be used as render target!")
                    }
                },
            )
            // Clamp to [1.0; infinity] range.
            .sup(&Vector2::new(1.0, 1.0));

        let scene_render_data = match self.scene_data_map.entry(scene_handle) {
            Entry::Occupied(entry) => {
                let render_data = entry.into_mut();
                recreate_render_data_if_needed(
                    scene_handle,
                    &*self.server,
                    &mut render_data.scene_data,
                    frame_size,
                    FrameTextureKind::Rectangle,
                )?;
                render_data
            }
            Entry::Vacant(entry) => {
                let render_data = entry.insert(SceneRenderData::new(
                    &*self.server,
                    frame_size,
                    FrameTextureKind::Rectangle,
                )?);
                info!(
                    "A new associated scene rendering data was created for scene {scene_handle}!"
                );
                render_data
            }
        };

        let pipeline_stats = &self.server.pipeline_statistics();
        scene_render_data.scene_data.statistics = Default::default();

        // If we specified a texture to draw to, we have to register it in texture cache
        // so it can be used in later on as texture. This is useful in case if you need
        // to draw something on offscreen and then draw it on some mesh.
        if let Some(rt) = scene.rendering_options.render_target.clone() {
            self.texture_cache.try_register(
                &*self.server,
                &rt,
                scene_render_data
                    .scene_data
                    .ldr_scene_frame_texture()
                    .clone(),
            )?;
        }

        scene_render_data
            .camera_data
            .retain(|h, _| graph.is_valid_handle(*h));

        let observers = ObserversCollection::from_scene(scene, frame_size);

        // At first, render the reflection probes to off-screen render target.
        let mut need_recalculate_convolution = false;
        for observer in observers.reflection_probes.iter() {
            let _debug_scope = self
                .server
                .begin_scope(&format!("Reflection Probe {:p}", observer));

            self.render_scene_observer(
                observer,
                scene_handle,
                scene,
                elapsed_time,
                dt,
                resource_manager,
                // There's no need to recalculate convolution for the environment map more than once
                // when rendering reflection probes, because it does not use a dynamic environment map.
                false,
            )?;
            need_recalculate_convolution = true;
        }

        // Then render everything else.
        for observer in observers.cameras.iter() {
            let _debug_scope = self.server.begin_scope(&format!("Camera {:p}", observer));

            self.render_scene_observer(
                observer,
                scene_handle,
                scene,
                elapsed_time,
                dt,
                resource_manager,
                need_recalculate_convolution,
            )?;
        }

        self.visibility_cache.update(graph);

        let scene_render_data = self.scene_data_map.get_mut(&scene_handle).unwrap();

        // Optionally render everything into back buffer.
        if scene.rendering_options.render_target.is_none() {
            scene_render_data.scene_data.statistics += blit_pixels(
                &mut self.uniform_buffer_cache,
                &self.backbuffer,
                scene_render_data.scene_data.ldr_scene_frame_texture(),
                &self.renderer_resources.shaders.blit,
                window_viewport,
                &self.renderer_resources,
            )?;
        }

        self.statistics += scene_render_data.scene_data.statistics;
        scene_render_data.scene_data.statistics.pipeline =
            self.server.pipeline_statistics() - *pipeline_stats;

        Ok(scene_render_data)
    }

    fn render_frame<'a>(
        &mut self,
        scenes: &SceneContainer,
        elapsed_time: f32,
        resource_manager: &ResourceManager,
        ui_render_info: impl Iterator<Item = UiRenderInfo<'a>>,
    ) -> Result<(), FrameworkError> {
        if self.frame_size.0 == 0 || self.frame_size.1 == 0 {
            return Ok(());
        }

        self.uniform_buffer_cache.mark_all_unused();
        self.uniform_memory_allocator.clear();
        self.dynamic_surface_cache.clear();

        // Make sure to drop associated data for destroyed scenes.
        self.scene_data_map
            .retain(|h, _| scenes.is_valid_handle(*h));

        // We have to invalidate resource bindings cache because some textures or programs,
        // or other GL resources can be destroyed and then on their "names" some new resource
        // are created, but cache still thinks that resource is correctly bound, but it is different
        // object have same name.
        self.server.invalidate_resource_bindings_cache();
        let dt = self.statistics.capped_frame_time;
        self.statistics.begin_frame();

        let window_viewport = Rect::new(0, 0, self.frame_size.0 as i32, self.frame_size.1 as i32);
        self.backbuffer.clear(
            window_viewport,
            Some(self.backbuffer_clear_color),
            Some(1.0),
            Some(0),
        );

        let backbuffer_width = self.frame_size.0 as f32;
        let backbuffer_height = self.frame_size.1 as f32;

        for (scene_handle, scene) in scenes.pair_iter().filter(|(_, s)| *s.enabled) {
            self.render_scene(scene_handle, scene, elapsed_time, dt, resource_manager)?;
        }

        self.graphics_server()
            .set_polygon_fill_mode(PolygonFace::FrontAndBack, PolygonFillMode::Fill);

        // Render UI on top of everything without gamma correction.
        for info in ui_render_info {
            self.render_ui(info)?;
        }

        let screen_matrix =
            Matrix4::new_orthographic(0.0, backbuffer_width, backbuffer_height, 0.0, -1.0, 1.0);
        self.screen_space_debug_renderer.render(
            &*self.server,
            &mut self.uniform_buffer_cache,
            window_viewport,
            &self.backbuffer,
            screen_matrix,
            &self.renderer_resources,
        )?;

        self.statistics.geometry_cache_size = self.geometry_cache.alive_count();
        self.statistics.texture_cache_size = self.texture_cache.alive_count();
        self.statistics.shader_cache_size = self.shader_cache.alive_count();
        self.statistics.uniform_buffer_cache_size = self.uniform_buffer_cache.alive_count();

        Ok(())
    }

    pub(crate) fn render_and_swap_buffers<'a>(
        &mut self,
        scenes: &SceneContainer,
        elapsed_time: f32,
        ui_info: impl Iterator<Item = UiRenderInfo<'a>>,
        window: &Window,
        resource_manager: &ResourceManager,
    ) -> Result<(), FrameworkError> {
        self.render_frame(scenes, elapsed_time, resource_manager, ui_info)?;
        self.statistics.end_frame();
        window.pre_present_notify();
        self.graphics_server().swap_buffers()?;
        self.statistics.finalize();
        self.statistics.pipeline = self.server.pipeline_statistics();
        Ok(())
    }
}