GPU: Discard data when getting texture before full clear (#5719)

* GPU: Discard data when getting texture before full clear

* Fix rules and order of clear checks

* Fix formatting

1 files changed, 50 insertions, 5 deletions

diff --git a/src/Ryujinx.Graphics.Gpu/Engine/Threed/DrawManager.cs b/src/Ryujinx.Graphics.Gpu/Engine/Threed/DrawManager.cs
index 18e7ac00..1c31312c 100644
--- a/src/Ryujinx.Graphics.Gpu/Engine/Threed/DrawManager.cs
+++ b/src/Ryujinx.Graphics.Gpu/Engine/Threed/DrawManager.cs
@@ -1,6 +1,7 @@
 using Ryujinx.Graphics.GAL;
 using Ryujinx.Graphics.Gpu.Engine.Threed.ComputeDraw;
 using Ryujinx.Graphics.Gpu.Engine.Types;
+using Ryujinx.Graphics.Gpu.Image;
 using Ryujinx.Graphics.Gpu.Memory;
 using System;
 
@@ -806,25 +807,69 @@ namespace Ryujinx.Graphics.Gpu.Engine.Threed
                 updateFlags |= RenderTargetUpdateFlags.Layered;
             }
 
-            if (clearDepth || clearStencil)
+            bool clearDS = clearDepth || clearStencil;
+
+            if (clearDS)
             {
                 updateFlags |= RenderTargetUpdateFlags.UpdateDepthStencil;
             }
 
-            engine.UpdateRenderTargetState(updateFlags, singleUse: componentMask != 0 ? index : -1);
-
             // If there is a mismatch on the host clip region and the one explicitly defined by the guest
             // on the screen scissor state, then we need to force only one texture to be bound to avoid
             // host clipping.
             var screenScissorState = _state.State.ScreenScissorState;
 
+            bool clearAffectedByStencilMask = (_state.State.ClearFlags & 1) != 0;
+            bool clearAffectedByScissor = (_state.State.ClearFlags & 0x100) != 0;
+
+            if (clearDS || componentMask == 15)
+            {
+                // A full clear if scissor is disabled, or it matches the screen scissor state.
+
+                bool fullClear = screenScissorState.X == 0 && screenScissorState.Y == 0;
+
+                if (fullClear && clearAffectedByScissor && _state.State.ScissorState[0].Enable)
+                {
+                    ref var scissorState = ref _state.State.ScissorState[0];
+
+                    fullClear = scissorState.X1 == screenScissorState.X &&
+                        scissorState.Y1 == screenScissorState.Y &&
+                        scissorState.X2 >= screenScissorState.X + screenScissorState.Width &&
+                        scissorState.Y2 >= screenScissorState.Y + screenScissorState.Height;
+                }
+
+                if (fullClear && clearDS)
+                {
+                    // Must clear all aspects of the depth-stencil format.
+
+                    FormatInfo dsFormat = _state.State.RtDepthStencilState.Format.Convert();
+
+                    bool hasDepth = dsFormat.Format.HasDepth();
+                    bool hasStencil = dsFormat.Format.HasStencil();
+
+                    if (hasStencil && (!clearStencil || (clearAffectedByStencilMask && _state.State.StencilTestState.FrontMask != 0xff)))
+                    {
+                        fullClear = false;
+                    }
+                    else if (hasDepth && !clearDepth)
+                    {
+                        fullClear = false;
+                    }
+                }
+
+                if (fullClear)
+                {
+                    updateFlags |= RenderTargetUpdateFlags.DiscardClip;
+                }
+            }
+
+            engine.UpdateRenderTargetState(updateFlags, singleUse: componentMask != 0 ? index : -1);
+
             // Must happen after UpdateRenderTargetState to have up-to-date clip region values.
             bool clipMismatch = (screenScissorState.X | screenScissorState.Y) != 0 ||
                                 screenScissorState.Width != _channel.TextureManager.ClipRegionWidth ||
                                 screenScissorState.Height != _channel.TextureManager.ClipRegionHeight;
 
-            bool clearAffectedByStencilMask = (_state.State.ClearFlags & 1) != 0;
-            bool clearAffectedByScissor = (_state.State.ClearFlags & 0x100) != 0;
             bool needsCustomScissor = !clearAffectedByScissor || clipMismatch;
 
             // Scissor and rasterizer discard also affect clears.