Framegraphs in rust

Cargo.toml

[package]
name = "framegraph-system"
version = "0.1.0"
edition = "2021"

[dependencies]
petgraph = "0.6.3"
wgpu = "0.15"
pollster = "0.3"

lib.rs

use std::collections::HashMap;
use petgraph::graph::{DiGraph, NodeIndex};

pub trait Resource: std::fmt::Debug {
    fn name(&self) -> &str;
}

pub trait RenderPass {
    fn name(&self) -> &str;
    fn inputs(&self) -> &[String];
    fn outputs(&self) -> &[String];
    fn execute(&self, context: &mut dyn ExecutionContext, resources: &HashMap<String, Box<dyn Resource>>);
}

pub trait ExecutionContext {
    fn create_resource(&mut self, name: &str, resource: Box<dyn Resource>);
    fn get_resource(&self, name: &str) -> Option<&dyn Resource>;
}

pub struct Framegraph {
    graph: DiGraph<Box<dyn RenderPass>, ()>,
    resources: HashMap<String, Box<dyn Resource>>,
}

impl Framegraph {
    pub fn new() -> Self {
        Framegraph {
            graph: DiGraph::new(),
            resources: HashMap::new(),
        }
    }

    pub fn add_pass(&mut self, pass: Box<dyn RenderPass>) -> NodeIndex {
        self.graph.add_node(pass)
    }

    pub fn add_dependency(&mut self, from: NodeIndex, to: NodeIndex) {
        self.graph.add_edge(from, to, ());
    }

    pub fn add_resource(&mut self, resource: Box<dyn Resource>) {
        self.resources.insert(resource.name().to_string(), resource);
    }

    pub fn execute(&self, context: &mut dyn ExecutionContext) {
        let mut visited = vec![false; self.graph.node_count()];
        
        for node in self.graph.node_indices() {
            self.dfs_execute(node, context, &mut visited);
        }
    }

    fn dfs_execute(&self, node: NodeIndex, context: &mut dyn ExecutionContext, visited: &mut Vec<bool>) {
        if visited[node.index()] {
            return;
        }

        for dep in self.graph.neighbors_directed(node, petgraph::Direction::Incoming) {
            self.dfs_execute(dep, context, visited);
        }

        let pass = &self.graph[node];
        pass.execute(context, &self.resources);

        visited[node.index()] = true;
    }
}

pub fn visualize_framegraph(fg: &Framegraph) -> String {
    use petgraph::dot::{Dot, Config};
    format!("{:?}", Dot::with_config(&fg.graph, &[Config::EdgeNoLabel]))
}

# src/wgpu_impl.rs
use crate::{Resource, RenderPass, ExecutionContext, Framegraph};
use std::collections::HashMap;
use std::sync::Arc;
use wgpu;

#[derive(Debug)]
pub enum WgpuResource {
    Texture(Arc<wgpu::Texture>),
    Buffer(Arc<wgpu::Buffer>),
}

impl Resource for WgpuResource {
    fn name(&self) -> &str {
        match self {
            WgpuResource::Texture(_) => "Texture",
            WgpuResource::Buffer(_) => "Buffer",
        }
    }
}

pub struct WgpuExecutionContext<'a> {
    pub device: &'a wgpu::Device,
    pub queue: &'a wgpu::Queue,
    pub encoder: &'a mut wgpu::CommandEncoder,
}

impl<'a> ExecutionContext for WgpuExecutionContext<'a> {
    fn create_resource(&mut self, name: &str, resource: Box<dyn Resource>) {
        // Implementation would create WGPU-specific resources
        println!("Creating resource: {}", name);
    }

    fn get_resource(&self, name: &str) -> Option<&dyn Resource> {
        // Implementation would retrieve WGPU-specific resources
        println!("Getting resource: {}", name);
        None
    }
}

pub struct ShadowMappingPass;
pub struct ZPrepass;
pub struct LightCullingPass;
pub struct ForwardRenderingPass;
pub struct TransparencyPass;
pub struct PostProcessingPass;

impl RenderPass for ShadowMappingPass {
    fn name(&self) -> &str { "Shadow Mapping" }
    fn inputs(&self) -> &[String] { &[] }
    fn outputs(&self) -> &[String] { &["shadow_map".to_string()] }
    fn execute(&self, context: &mut dyn ExecutionContext, resources: &HashMap<String, Box<dyn Resource>>) {
        println!("Executing Shadow Mapping pass");
        // Actual implementation would use WGPU to render shadow maps
    }
}

impl RenderPass for ZPrepass {
    fn name(&self) -> &str { "Z-Prepass" }
    fn inputs(&self) -> &[String] { &[] }
    fn outputs(&self) -> &[String] { &["depth".to_string()] }
    fn execute(&self, context: &mut dyn ExecutionContext, resources: &HashMap<String, Box<dyn Resource>>) {
        println!("Executing Z-Prepass");
        // Actual implementation would use WGPU to render depth
    }
}

impl RenderPass for LightCullingPass {
    fn name(&self) -> &str { "Light Culling" }
    fn inputs(&self) -> &[String] { &["depth".to_string()] }
    fn outputs(&self) -> &[String] { &["light_list".to_string(), "light_grid".to_string()] }
    fn execute(&self, context: &mut dyn ExecutionContext, resources: &HashMap<String, Box<dyn Resource>>) {
        println!("Executing Light Culling pass");
        // Actual implementation would use WGPU to perform light culling
    }
}

impl RenderPass for ForwardRenderingPass {
    fn name(&self) -> &str { "Forward Rendering" }
    fn inputs(&self) -> &[String] { &["depth".to_string(), "shadow_map".to_string(), "light_list".to_string(), "light_grid".to_string()] }
    fn outputs(&self) -> &[String] { &["color".to_string()] }
    fn execute(&self, context: &mut dyn ExecutionContext, resources: &HashMap<String, Box<dyn Resource>>) {
        println!("Executing Forward Rendering pass");
        // Actual implementation would use WGPU to perform forward rendering
    }
}

impl RenderPass for TransparencyPass {
    fn name(&self) -> &str { "Transparency" }
    fn inputs(&self) -> &[String] { &["depth".to_string(), "color".to_string(), "shadow_map".to_string(), "light_list".to_string(), "light_grid".to_string()] }
    fn outputs(&self) -> &[String] { &["final_color".to_string()] }
    fn execute(&self, context: &mut dyn ExecutionContext, resources: &HashMap<String, Box<dyn Resource>>) {
        println!("Executing Transparency pass");
        // Actual implementation would use WGPU to render transparent objects
    }
}

impl RenderPass for PostProcessingPass {
    fn name(&self) -> &str { "Post-processing" }
    fn inputs(&self) -> &[String] { &["final_color".to_string()] }
    fn outputs(&self) -> &[String] { &["output".to_string()] }
    fn execute(&self, context: &mut dyn ExecutionContext, resources: &HashMap<String, Box<dyn Resource>>) {
        println!("Executing Post-processing pass");
        // Actual implementation would use WGPU to apply post-processing effects
    }
}

pub fn create_advanced_forward_plus_framegraph() -> Framegraph {
    let mut fg = Framegraph::new();

    // Add resources
    fg.add_resource(Box::new(WgpuResource::Texture(Arc::new(wgpu::Texture::default()))));
    fg.add_resource(Box::new(WgpuResource::Buffer(Arc::new(wgpu::Buffer::default()))));
    // Add more resources...

    // Add passes
    let shadow_node = fg.add_pass(Box::new(ShadowMappingPass));
    let z_prepass_node = fg.add_pass(Box::new(ZPrepass));
    let light_culling_node = fg.add_pass(Box::new(LightCullingPass));
    let forward_node = fg.add_pass(Box::new(ForwardRenderingPass));
    let transparency_node = fg.add_pass(Box::new(TransparencyPass));
    let post_processing_node = fg.add_pass(Box::new(PostProcessingPass));

    // Add dependencies
    fg.add_dependency(shadow_node, forward_node);
    fg.add_dependency(z_prepass_node, light_culling_node);
    fg.add_dependency(light_culling_node, forward_node);
    fg.add_dependency(forward_node, transparency_node);
    fg.add_dependency(transparency_node, post_processing_node);

    fg
}

main.rs

use crate::wgpu_impl::{create_advanced_forward_plus_framegraph, WgpuExecutionContext};
use framegraph_system::visualize_framegraph;

fn main() {
    // Setup wgpu
    let instance = wgpu::Instance::new(wgpu::InstanceDescriptor::default());
    let adapter = pollster::block_on(instance.request_adapter(&wgpu::RequestAdapterOptions::default())).unwrap();
    let (device, queue) = pollster::block_on(adapter.request_device(&wgpu::DeviceDescriptor::default(), None)).unwrap();

    // Create and execute the advanced Forward+ framegraph
    let framegraph = create_advanced_forward_plus_framegraph();
    let mut encoder = device.create_command_encoder(&wgpu::CommandEncoderDescriptor::default());
    
    {
        let mut context = WgpuExecutionContext {
            device: &device,
            queue: &queue,
            encoder: &mut encoder,
        };
        framegraph.execute(&mut context);
    }

    queue.submit(Some(encoder.finish()));

    println!("Advanced Forward+ Framegraph execution complete");

    // Visualize the framegraph
    println!("{}", visualize_framegraph(&framegraph));
}