Scissor test implementation. Partially stubbed until geometry shaders… (#556)

* Scissor test implementation. Partially stubbed until geometry shaders are fixed

* Apply to all viewports when geometry shaders are disabled.

* Also apply enable cap to all viewports when geometry shaders are disabled

* Added fixme as per suggestion

Co-Authored-By: BaronKiko <BaronKiko@users.noreply.github.com>

* Apparently no alignment needed here.

* Comment on new line

* Correct height calculation

2 files changed, 39 insertions, 0 deletions

diff --git a/Ryujinx.Graphics/Graphics3d/NvGpuEngine3d.cs b/Ryujinx.Graphics/Graphics3d/NvGpuEngine3d.cs
index dc1eec3b..9a22c85f 100644
--- a/Ryujinx.Graphics/Graphics3d/NvGpuEngine3d.cs
+++ b/Ryujinx.Graphics/Graphics3d/NvGpuEngine3d.cs
@@ -24,6 +24,9 @@ namespace Ryujinx.Graphics.Graphics3d
 
         private ConstBuffer[][] ConstBuffers;
 
+        // Height kept for flipping y axis
+        private int ViewportHeight = 0;
+
         private int CurrentInstance = 0;
 
         public NvGpuEngine3d(NvGpu Gpu)
@@ -97,6 +100,7 @@ namespace Ryujinx.Graphics.Graphics3d
             SetCullFace(State);
             SetDepth(State);
             SetStencil(State);
+            SetScissor(State);
             SetBlending(State);
             SetColorMask(State);
             SetPrimitiveRestart(State);
@@ -208,6 +212,8 @@ namespace Ryujinx.Graphics.Graphics3d
 
             Gpu.ResourceManager.SendColorBuffer(Vmm, Key, FbIndex, Image);
 
+            ViewportHeight = VpH;
+
             Gpu.Renderer.RenderTarget.SetViewport(FbIndex, VpX, VpY, VpW, VpH);
         }
 
@@ -407,6 +413,36 @@ namespace Ryujinx.Graphics.Graphics3d
             }
         }
 
+        private void SetScissor(GalPipelineState State)
+        {
+            // FIXME: Stubbed, only the first scissor test is valid without a geometry shader loaded. At time of writing geometry shaders are also stubbed.
+            // Once geometry shaders are fixed it should be equal to GalPipelineState.RenderTargetCount when shader loaded, otherwise equal to 1
+            State.ScissorTestCount = 1;
+
+            for (int Index = 0; Index < GalPipelineState.RenderTargetsCount; Index++)
+            {
+                State.ScissorTestEnabled[Index] = ReadRegisterBool(NvGpuEngine3dReg.ScissorEnable + Index * 4);
+
+                if (State.ScissorTestEnabled[Index])
+                {
+                    uint ScissorHorizontal        = (uint)ReadRegister(NvGpuEngine3dReg.ScissorHorizontal + Index * 4);
+                    uint ScissorVertical          = (uint)ReadRegister(NvGpuEngine3dReg.ScissorVertical + Index * 4);
+
+                    State.ScissorTestX[Index]     = (int)((ScissorHorizontal & 0xFFFF) * State.FlipX);                          // X, lower 16 bits
+                    State.ScissorTestWidth[Index] = (int)((ScissorHorizontal >> 16) * State.FlipX) - State.ScissorTestX[Index]; // Width, right side is upper 16 bits
+
+                    State.ScissorTestY[Index]      = (int)((ScissorVertical & 0xFFFF));                                         // Y, lower 16 bits
+                    State.ScissorTestHeight[Index] = (int)((ScissorVertical >> 16)) - State.ScissorTestY[Index];                // Height, top side is upper 16 bits
+
+                    // Y coordinates may have to be flipped
+                    if ((int)State.FlipY == -1)
+                    {
+                        State.ScissorTestY[Index] = ViewportHeight - State.ScissorTestY[Index] - State.ScissorTestHeight[Index];
+                    }
+                }
+            }
+        }
+
         private void SetBlending(GalPipelineState State)
         {
             bool BlendIndependent = ReadRegisterBool(NvGpuEngine3dReg.BlendIndependent);
diff --git a/Ryujinx.Graphics/Graphics3d/NvGpuEngine3dReg.cs b/Ryujinx.Graphics/Graphics3d/NvGpuEngine3dReg.cs
index 30243c02..026b0cd1 100644
--- a/Ryujinx.Graphics/Graphics3d/NvGpuEngine3dReg.cs
+++ b/Ryujinx.Graphics/Graphics3d/NvGpuEngine3dReg.cs
@@ -22,6 +22,9 @@ namespace Ryujinx.Graphics.Graphics3d
         ClearNColor          = 0x360,
         ClearDepth           = 0x364,
         ClearStencil         = 0x368,
+        ScissorEnable        = 0x380,
+        ScissorHorizontal    = 0x381,
+        ScissorVertical      = 0x382,
         StencilBackFuncRef   = 0x3d5,
         StencilBackMask      = 0x3d6,
         StencilBackFuncMask  = 0x3d7,