Merge pull request #10251 from Pokechu22/negative-scissor

Rework scissor handling

1 files changed, 22 insertions, 7 deletions

diff --git a/Source/Core/VideoBackends/Software/Clipper.cpp b/Source/Core/VideoBackends/Software/Clipper.cpp
index f13ebb90b7..ae6b60f1ee 100644
--- a/Source/Core/VideoBackends/Software/Clipper.cpp
+++ b/Source/Core/VideoBackends/Software/Clipper.cpp
@@ -307,7 +307,7 @@ void ProcessTriangle(OutputVertexData* v0, OutputVertexData* v1, OutputVertexDat
       PerspectiveDivide(v0);
       PerspectiveDivide(v1);
       PerspectiveDivide(v2);
-      Rasterizer::UpdateZSlope(v0, v1, v2);
+      Rasterizer::UpdateZSlope(v0, v1, v2, bpmem.scissorOffset.x * 2, bpmem.scissorOffset.y * 2);
       INCSTAT(g_stats.this_frame.num_triangles_culled)
       return;
     }
@@ -320,7 +320,7 @@ void ProcessTriangle(OutputVertexData* v0, OutputVertexData* v1, OutputVertexDat
       PerspectiveDivide(v0);
       PerspectiveDivide(v2);
       PerspectiveDivide(v1);
-      Rasterizer::UpdateZSlope(v0, v2, v1);
+      Rasterizer::UpdateZSlope(v0, v2, v1, bpmem.scissorOffset.x * 2, bpmem.scissorOffset.y * 2);
       INCSTAT(g_stats.this_frame.num_triangles_culled)
       return;
     }
@@ -345,7 +345,24 @@ void ProcessTriangle(OutputVertexData* v0, OutputVertexData* v1, OutputVertexDat
     Vertices[2] = v2;
   }
 
-  ClipTriangle(indices, &numIndices);
+  // TODO: behavior when disable_clipping_detection is set doesn't quite match actual hardware;
+  // there does still seem to be a maximum size after which things are clipped.  Also, currently
+  // when clipping is enabled triangles are clipped to exactly the viewport, but on hardware there
+  // is a guardband (and with certain scissor configurations, things can show up in it)
+  // Mario Party 8 in widescreen breaks without this: https://bugs.dolphin-emu.org/issues/12769
+  bool skip_clipping = false;
+  if (xfmem.clipDisable.disable_clipping_detection)
+  {
+    // If any w coordinate is negative, then the perspective divide will flip coordinates, breaking
+    // various assumptions (including backface).  So, we still need to do clipping in that case.
+    // This isn't the actual condition hardware uses.
+    if (Vertices[0]->projectedPosition.w >= 0 && Vertices[1]->projectedPosition.w >= 0 &&
+        Vertices[2]->projectedPosition.w >= 0)
+      skip_clipping = true;
+  }
+
+  if (!skip_clipping)
+    ClipTriangle(indices, &numIndices);
 
   for (int i = 0; i + 3 <= numIndices; i += 3)
   {
@@ -533,10 +550,8 @@ void PerspectiveDivide(OutputVertexData* vertex)
   Vec3& screen = vertex->screenPosition;
 
   float wInverse = 1.0f / projected.w;
-  screen.x =
-      projected.x * wInverse * xfmem.viewport.wd + xfmem.viewport.xOrig - bpmem.scissorOffset.x * 2;
-  screen.y =
-      projected.y * wInverse * xfmem.viewport.ht + xfmem.viewport.yOrig - bpmem.scissorOffset.y * 2;
+  screen.x = projected.x * wInverse * xfmem.viewport.wd + xfmem.viewport.xOrig;
+  screen.y = projected.y * wInverse * xfmem.viewport.ht + xfmem.viewport.yOrig;
   screen.z = projected.z * wInverse * xfmem.viewport.zRange + xfmem.viewport.farZ;
 }
 }  // namespace Clipper