From fc0560087fde6f517c4141a6fa674ad92fead081 Mon Sep 17 00:00:00 2001
From: Connor McLaughlin <stenzek@gmail.com>
Date: Sun, 14 Jun 2020 01:01:01 +1000
Subject: [PATCH] GPU: Skip primitives where clip area is invalid

Fixes palettes being overwritten/menus being broken in
Yoshimoto Mahjong Club Deluxe.
---
 src/core/gpu.h      |  3 +++
 src/core/gpu_hw.cpp | 12 ++++++++++++
 src/core/gpu_sw.cpp | 10 +++++++++-
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/core/gpu.h b/src/core/gpu.h
index c29e04739..6aebc1abc 100644
--- a/src/core/gpu.h
+++ b/src/core/gpu.h
@@ -394,6 +394,9 @@ protected:
            BoolToUInt8(m_render_command.shading_enable);
   }
 
+  /// Returns true if the drawing area is valid (i.e. left <= right, top <= bottom).
+  ALWAYS_INLINE bool IsDrawingAreaIsValid() const { return m_drawing_area.Valid(); }
+
   void AddCommandTicks(TickCount ticks);
 
   void WriteGP1(u32 value);
diff --git a/src/core/gpu_hw.cpp b/src/core/gpu_hw.cpp
index 569e49c45..edbe39b22 100644
--- a/src/core/gpu_hw.cpp
+++ b/src/core/gpu_hw.cpp
@@ -217,6 +217,9 @@ void GPU_HW::LoadVertices()
       if (rc.quad_polygon && m_resolution_scale > 1)
         HandleFlippedQuadTextureCoordinates(vertices.data());
 
+      if (!IsDrawingAreaIsValid())
+        return;
+
       // Cull polygons which are too large.
       const s32 min_x_12 = std::min(vertices[1].x, vertices[2].x);
       const s32 max_x_12 = std::max(vertices[1].x, vertices[2].x);
@@ -328,6 +331,9 @@ void GPU_HW::LoadVertices()
       // we can split the rectangle up into potentially 8 quads
       DebugAssert(GetBatchVertexSpace() >= MAX_VERTICES_FOR_RECTANGLE);
 
+      if (!IsDrawingAreaIsValid())
+        return;
+
       // Split the rectangle into multiple quads if it's greater than 256x256, as the texture page should repeat.
       u16 tex_top = orig_tex_top;
       for (s32 y_offset = 0; y_offset < rectangle_height;)
@@ -395,6 +401,9 @@ void GPU_HW::LoadVertices()
           pos1.bits = m_fifo.Pop();
         }
 
+        if (!IsDrawingAreaIsValid())
+          return;
+
         BatchVertex start, end;
         start.Set(m_drawing_offset.x + pos0.x, m_drawing_offset.y + pos0.y, color0, 0, 0);
         end.Set(m_drawing_offset.x + pos1.x, m_drawing_offset.y + pos1.y, color1, 0, 0);
@@ -428,6 +437,9 @@ void GPU_HW::LoadVertices()
         const u32 num_vertices = GetPolyLineVertexCount();
         DebugAssert(GetBatchVertexSpace() >= (num_vertices * 2));
 
+        if (!IsDrawingAreaIsValid())
+          return;
+
         const u32 first_color = rc.color_for_first_vertex;
         const bool shaded = rc.shading_enable;
 
diff --git a/src/core/gpu_sw.cpp b/src/core/gpu_sw.cpp
index a129088d8..c058ece3e 100644
--- a/src/core/gpu_sw.cpp
+++ b/src/core/gpu_sw.cpp
@@ -248,6 +248,9 @@ void GPU_SW::DispatchRenderCommand()
         }
       }
 
+      if (!IsDrawingAreaIsValid())
+        return;
+
       const DrawTriangleFunction DrawFunction = GetDrawTriangleFunction(
         rc.shading_enable, rc.texture_enable, rc.raw_texture_enable, rc.transparency_enable, dithering_enable);
 
@@ -296,6 +299,9 @@ void GPU_SW::DispatchRenderCommand()
         break;
       }
 
+      if (!IsDrawingAreaIsValid())
+        return;
+
       const DrawRectangleFunction DrawFunction =
         GetDrawRectangleFunction(rc.texture_enable, rc.raw_texture_enable, rc.transparency_enable);
 
@@ -334,7 +340,9 @@ void GPU_SW::DispatchRenderCommand()
           p1->SetPosition(VertexPosition{m_fifo.Pop()});
         }
 
-        (this->*DrawFunction)(p0, p1);
+        // down here because of the FIFO pops
+        if (IsDrawingAreaIsValid())
+          (this->*DrawFunction)(p0, p1);
 
         // swap p0/p1 so that the last vertex is used as the first for the next line
         std::swap(p0, p1);