From e4f5f0bcaf39defa256190f285b33882d8446780 Mon Sep 17 00:00:00 2001
From: Ian Curtis <i.curtis@gmail.com>
Date: Sun, 2 Sep 2018 21:36:24 +0000
Subject: [PATCH] Sega bass fishing is starting some off the meshes with a
 shared vertex. Without having a previous vertex to share with, the values
 were just uninitialised and junk. The hardware itself seems to hold the value
 from the previous mesh, and sega bass fishing relies on this undefined
 behaviour to function correctly. Storing the cached vertices as member
 variables instead of locally to the function means it holds the values from
 the last mesh, and uses those values instead of random garbage.

---
 Src/Graphics/New3D/New3D.cpp | 41 ++++++++++++++++++------------------
 Src/Graphics/New3D/New3D.h   |  3 +++
 2 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/Src/Graphics/New3D/New3D.cpp b/Src/Graphics/New3D/New3D.cpp
index 3dd339b..bde3bdc 100644
--- a/Src/Graphics/New3D/New3D.cpp
+++ b/Src/Graphics/New3D/New3D.cpp
@@ -23,12 +23,12 @@ CNew3D::CNew3D(const Util::Config::Node &config, std::string gameName)
 	m_cullingRAMHi	= nullptr;
 	m_polyRAM		= nullptr;
 	m_vrom			= nullptr;
-	m_textureRAM	= nullptr;
-	m_sunClamp		= true;
-	m_shadeIsSigned = true;
-}
-
-CNew3D::~CNew3D()
+	m_textureRAM	= nullptr;
+	m_sunClamp		= true;
+	m_shadeIsSigned = true;
+}
+
+CNew3D::~CNew3D()
 {
 	m_vbo.Destroy();
 }
@@ -1026,9 +1026,7 @@ void CNew3D::SetMeshValues(SortingMesh *currentMesh, PolyHeader &ph)
 
 void CNew3D::CacheModel(Model *m, const UINT32 *data)
 {
-	Vertex			prev[4];
 	UINT16			texCoords[4][2];
-	UINT16			prevTexCoords[4][2];
 	PolyHeader		ph;
 	UINT64			lastHash	= -1;
 	SortingMesh*	currentMesh = nullptr;
@@ -1086,10 +1084,10 @@ void CNew3D::CacheModel(Model *m, const UINT32 *data)
 		{
 			if (ph.SharedVertex(i))
 			{
-				p.v[j] = prev[i];
+				p.v[j] = m_prev[i];
 
-				texCoords[j][0] = prevTexCoords[i][0];
-				texCoords[j][1] = prevTexCoords[i][1];
+				texCoords[j][0] = m_prevTexCoords[i][0];
+				texCoords[j][1] = m_prevTexCoords[i][1];
 
 				//check if we need to recalc tex coords - will only happen if tex tiles are different + sharing vertices
 				if (hash != lastHash) {
@@ -1178,7 +1176,8 @@ void CNew3D::CacheModel(Model *m, const UINT32 *data)
 				p.v[j].fixedShade = shade;
 			}
 
-			float texU, texV = 0;
+			float texU = 0;
+			float texV = 0;
 
 			// tex coords
 			if (currentMesh->textured) {
@@ -1233,9 +1232,9 @@ void CNew3D::CacheModel(Model *m, const UINT32 *data)
 		
 		// Copy current vertices into previous vertex array
 		for (i = 0; i < 4; i++) {
-			prev[i] = p.v[i];
-			prevTexCoords[i][0] = texCoords[i][0];
-			prevTexCoords[i][1] = texCoords[i][1];
+			m_prev[i] = p.v[i];
+			m_prevTexCoords[i][0] = texCoords[i][0];
+			m_prevTexCoords[i][1] = texCoords[i][1];
 		}
 
 	} while (ph.NextPoly());
@@ -1659,10 +1658,10 @@ void CNew3D::SetSunClamp(bool enable)
 {
 	m_sunClamp = enable;
 }
-
-void CNew3D::SetSignedShade(bool enable)
-{
-	m_shadeIsSigned = enable;
-}
-
+
+void CNew3D::SetSignedShade(bool enable)
+{
+	m_shadeIsSigned = enable;
+}
+
 } // New3D
diff --git a/Src/Graphics/New3D/New3D.h b/Src/Graphics/New3D/New3D.h
index 321d37b..1e74263 100644
--- a/Src/Graphics/New3D/New3D.h
+++ b/Src/Graphics/New3D/New3D.h
@@ -250,6 +250,9 @@ private:
 	NodeAttributes	m_nodeAttribs;
 	Mat4			m_modelMat;				// current modelview matrix
 
+	Vertex			m_prev[4];				// these are class variables because sega bass fishing starts meshes with shared vertices from the previous one
+	UINT16			m_prevTexCoords[4][2];	// basically relying on undefined behavour
+
 	std::vector<Node> m_nodes;				// this represents the entire render frame
 	std::vector<Poly> m_polyBufferRam;		// dynamic polys
 	std::vector<Poly> m_polyBufferRom;		// rom polys