sbox-public/engine/Sandbox.Engine/Systems/UI/Render/PanelRenderer.cs

using Sandbox.Rendering;

namespace Sandbox.UI;

internal sealed partial class PanelRenderer
{
	public Rect Screen { get; internal set; }

	readonly object _lock = new();

	readonly UIBatcher batcher = new();
	readonly List<GPUBoxInstance> pendingInstances = new();
	readonly List<DeferredInstance> deferredInstances = new();
	int batchIndex;

	[ConVar( "ui_visualize_batches", Help = "Visualize UI draw batches with colored overlays" )]
	internal static bool DebugVisualizeBatches { get; set; }

	bool isWorldPanelContext;
	int WorldPanelCombo => isWorldPanelContext ? 1 : 0;
	Matrix? worldPanelMat;
	internal RenderTarget DefaultRenderTarget;

	internal void AdvanceFrame()
	{
		lock ( _lock )
			batcher.AdvanceFrame();
	}

	internal void BuildDescriptors( RootPanel panel, float opacity = 1.0f )
	{
		lock ( _lock )
		{
			Screen = panel.PanelBounds;
			isWorldPanelContext = panel.IsWorldPanel;
			Matrix = Matrix.Identity;

			RenderModeStack.Clear();
			RenderModeStack.Push( "normal" );
			SetRenderMode( "normal" );

			DefaultRenderTarget = Graphics.RenderTarget;
			LayerStack?.Clear();
			InitScissor( Screen );

			BuildDescriptors( (Panel)panel, new RenderState { X = Screen.Left, Y = Screen.Top, Width = Screen.Width, Height = Screen.Height, RenderOpacity = opacity } );
		}
	}

	internal void BuildCommandList( RootPanel root, float opacity = 1.0f )
	{
		lock ( _lock )
		{
			var cl = root.PanelCommandList;
			cl.Reset();

			Screen = root.PanelBounds;
			DefaultRenderTarget = Graphics.RenderTarget;
			isWorldPanelContext = root.IsWorldPanel;
			worldPanelMat = null;

			if ( root is WorldPanel worldPanel )
			{
				worldPanelMat = Sandbox.ScenePanelObject.BuildPanelToWorldMatrix( worldPanel.Transform );
			}

			LayerStack?.Clear();
			pendingInstances.Clear();
			deferredInstances.Clear();
			deferredOrder = 0;
			zDepth = 0;
			pendingBlendMode = BlendMode.Normal;
			backdropGrabActive = false;
			batchIndex = 0;

			cl.Attributes.Set( "LayerMat", Matrix.Identity );
			cl.Attributes.SetCombo( "D_WORLDPANEL", WorldPanelCombo );
			if ( worldPanelMat.HasValue )
				cl.Attributes.Set( "WorldMat", worldPanelMat.Value );
			InitScissor( Screen, cl );

			DrawPanel( root, cl );
			FlushBatch( cl );

			Stats.ScissorCount = batcher.ScissorCount;
			Stats.GpuBufferCount = batcher.GpuBufferCount;
		}
	}

	internal bool IsWorldPanel( Panel panel )
	{
		if ( panel is RootPanel { IsWorldPanel: true } )
			return true;

		return panel.FindRootPanel()?.IsWorldPanel ?? false;
	}

	//
	// Stats
	//

	internal struct FrameStats
	{
		public int Panels;
		public int BatchedPanels;
		public int InlinePanels;
		public int LayerPanels;
		public int DrawCalls;
		public int InstanceCount;
		public int FlushCount;
		public int FrameGrabs;
		public int ScissorCount;
		public int GpuBufferCount;

		public void Reset() => this = default;
	}

	internal static FrameStats Stats;
}