From 77d0a0d76e28df3d2393d62ff98ce3cec4431f33 Mon Sep 17 00:00:00 2001
From: StapleButter <thetotalworm@gmail.com>
Date: Thu, 1 Jun 2017 15:16:44 +0200
Subject: only do lower-pixel rendering when rendering under an edge

---
 src/GPU3D_Soft.cpp | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

(limited to 'src/GPU3D_Soft.cpp')

diff --git a/src/GPU3D_Soft.cpp b/src/GPU3D_Soft.cpp
index 07222f2..e78524d 100644
--- a/src/GPU3D_Soft.cpp
+++ b/src/GPU3D_Soft.cpp
@@ -1027,10 +1027,14 @@ void RenderPolygonScanline(RendererPolygon* rp, s32 y)
             continue;
         }
 
+        u32 dstattr = AttrBuffer[pixeladdr];
+
         // if depth test against the topmost pixel fails, test
         // against the pixel underneath
         if (!fnDepthTest(DepthBuffer[pixeladdr], z))
         {
+            if (!(dstattr & 0x3)) continue;
+
             pixeladdr += 258;
             if (!fnDepthTest(DepthBuffer[pixeladdr], z))
                 continue;
@@ -1096,7 +1100,6 @@ void RenderPolygonScanline(RendererPolygon* rp, s32 y)
         }
         else
         {
-            u32 dstattr = AttrBuffer[pixeladdr];
             attr |= (1<<30);
             if (polygon->IsShadow) dstattr |= (1<<30);
 
@@ -1148,10 +1151,14 @@ void RenderPolygonScanline(RendererPolygon* rp, s32 y)
             continue;
         }
 
+        u32 dstattr = AttrBuffer[pixeladdr];
+
         // if depth test against the topmost pixel fails, test
         // against the pixel underneath
         if (!fnDepthTest(DepthBuffer[pixeladdr], z))
         {
+            if (!(dstattr & 0x3)) continue;
+
             pixeladdr += 258;
             if (!fnDepthTest(DepthBuffer[pixeladdr], z))
                 continue;
@@ -1244,10 +1251,14 @@ void RenderPolygonScanline(RendererPolygon* rp, s32 y)
             continue;
         }
 
+        u32 dstattr = AttrBuffer[pixeladdr];
+
         // if depth test against the topmost pixel fails, test
         // against the pixel underneath
         if (!fnDepthTest(DepthBuffer[pixeladdr], z))
         {
+            if (!(dstattr & 0x3)) continue;
+
             pixeladdr += 258;
             if (!fnDepthTest(DepthBuffer[pixeladdr], z))
                 continue;
@@ -1313,7 +1324,6 @@ void RenderPolygonScanline(RendererPolygon* rp, s32 y)
         }
         else
         {
-            u32 dstattr = AttrBuffer[pixeladdr];
             attr |= (1<<30);
             if (polygon->IsShadow) dstattr |= (1<<30);
 
-- 
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