GhostEngine/Ghost.RenderGraph.Concept/RenderGraphPassBuilder.cs

namespace Ghost.RenderGraph.Concept;

public interface IRenderGraphBuilder
{
    RenderGraphTextureHandle ReadTexture(RenderGraphTextureHandle handle);
    RenderGraphTextureHandle WriteTexture(RenderGraphTextureHandle handle);
    RenderGraphTextureHandle UseDepthBuffer(RenderGraphTextureHandle handle, bool writeAccess);
    RenderGraphTextureHandle CreateTexture(TextureDescriptor descriptor);
    RenderGraphBufferHandle ReadBuffer(RenderGraphBufferHandle handle);
    RenderGraphBufferHandle WriteBuffer(RenderGraphBufferHandle handle);
    RenderGraphBufferHandle CreateBuffer(BufferDescriptor descriptor);
}

public class RenderGraphPassBuilder<TPassData> : IRenderGraphBuilder, IDisposable
    where TPassData : class, new()
{
    private readonly RenderGraph _graph;
    private readonly string _passName;
    private readonly int _passIndex;
    private readonly List<(RenderGraphResourceHandle handle, ResourceState state)> _resourceAccesses = new();
    private Action<TPassData, ICommandBuffer>? _renderFunc;
    private bool _committed;
    private bool _allowCulling = true;

    public TPassData PassData { get; }

    internal RenderGraphPassBuilder(RenderGraph graph, string passName, int passIndex)
    {
        _graph = graph;
        _passName = passName;
        _passIndex = passIndex;
        PassData = new TPassData();
    }

    internal IReadOnlyList<(RenderGraphResourceHandle handle, ResourceState state)> ResourceAccesses => _resourceAccesses;
    internal Action<TPassData, ICommandBuffer>? RenderFunc => _renderFunc;
    internal bool AllowCulling => _allowCulling;

    public RenderGraphTextureHandle ReadTexture(RenderGraphTextureHandle handle)
    {
        _resourceAccesses.Add((handle, ResourceState.ShaderResource));
        return handle;
    }

    public RenderGraphTextureHandle WriteTexture(RenderGraphTextureHandle handle)
    {
        _resourceAccesses.Add((handle, ResourceState.RenderTarget));
        return handle;
    }

    public RenderGraphTextureHandle UseDepthBuffer(RenderGraphTextureHandle handle, bool writeAccess)
    {
        _resourceAccesses.Add((handle, writeAccess ? ResourceState.DepthWrite : ResourceState.DepthRead));
        return handle;
    }

    public RenderGraphTextureHandle CreateTexture(TextureDescriptor descriptor)
    {
        var handle = _graph.CreateTransientTexture(descriptor);
        return handle;
    }

    public RenderGraphBufferHandle ReadBuffer(RenderGraphBufferHandle handle)
    {
        _resourceAccesses.Add((handle, ResourceState.ShaderResource));
        return handle;
    }

    public RenderGraphBufferHandle WriteBuffer(RenderGraphBufferHandle handle)
    {
        _resourceAccesses.Add((handle, ResourceState.UnorderedAccess));
        return handle;
    }

    public RenderGraphBufferHandle CreateBuffer(BufferDescriptor descriptor)
    {
        var handle = _graph.CreateTransientBuffer(descriptor);
        return handle;
    }

    public void SetRenderFunc(Action<TPassData, ICommandBuffer> renderFunc)
    {
        _renderFunc = renderFunc;
    }

    /// <summary>
    /// Controls whether this pass can be culled if it doesn't contribute to the final output.
    /// Set to false for synchronization passes, debug markers, or async compute boundaries.
    /// Default is true.
    /// </summary>
    public void SetAllowCulling(bool allowCulling)
    {
        _allowCulling = allowCulling;
    }

    public void Dispose()
    {
        // Commit the pass when disposed (at end of using block)
        if (!_committed)
        {
            _graph.CommitPass(this, _passName);
            _committed = true;
        }
    }
}