From 36074d9fd53b6416f9e0fc14070158b710cf48aa Mon Sep 17 00:00:00 2001
From: Ian Curtis <i.curtis@gmail.com>
Date: Mon, 30 May 2016 13:25:00 +0000
Subject: [PATCH] Y texture offsets are just 5 bits. Texture coordinate wrap
 around happens in the same texture sheet, not into the next one. Fixes
 various texturing bugs in sega rally.

---
 Src/Graphics/New3D/Model.cpp |  8 ++++----
 Src/Graphics/New3D/Model.h   |  5 +++--
 Src/Graphics/New3D/New3D.cpp | 28 +++++++++++++++++++++++++---
 Src/Graphics/New3D/New3D.h   |  2 ++
 4 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/Src/Graphics/New3D/Model.cpp b/Src/Graphics/New3D/Model.cpp
index ee9eae3..c2ab778 100644
--- a/Src/Graphics/New3D/Model.cpp
+++ b/Src/Graphics/New3D/Model.cpp
@@ -6,7 +6,7 @@ NodeAttributes::NodeAttributes()
 {
 	currentTexOffsetX = 0;
 	currentTexOffsetY = 0;
-	currentTexOffset = 0;
+	page = 0;
 }
 
 bool NodeAttributes::Push()
@@ -20,7 +20,7 @@ bool NodeAttributes::Push()
 		return false;
 	}
 
-	na.texOffset = currentTexOffset;
+	na.page = page;
 	na.texOffsetX = currentTexOffsetX;
 	na.texOffsetY = currentTexOffsetY;
 
@@ -35,7 +35,7 @@ bool NodeAttributes::Pop()
 		return false;	// check for underflow
 	}
 
-	currentTexOffset = m_vecAttribs.back().texOffset;
+	page = m_vecAttribs.back().page;
 	currentTexOffsetX = m_vecAttribs.back().texOffsetX;
 	currentTexOffsetY = m_vecAttribs.back().texOffsetY;
 
@@ -51,7 +51,7 @@ bool NodeAttributes::StackLimit()
 
 void NodeAttributes::Reset()
 {
-	currentTexOffset = 0;
+	page = 0;
 	currentTexOffsetX = 0;
 	currentTexOffsetY = 0;
 	m_vecAttribs.clear();
diff --git a/Src/Graphics/New3D/Model.h b/Src/Graphics/New3D/Model.h
index 71c360d..2f442f0 100644
--- a/Src/Graphics/New3D/Model.h
+++ b/Src/Graphics/New3D/Model.h
@@ -80,6 +80,7 @@ struct Model
 	// texture offsets for model
 	int textureOffsetX = 0;
 	int textureOffsetY = 0;
+	int page = 0;
 
 	//matrices
 	float modelMat[16];
@@ -112,7 +113,7 @@ public:
 
 	int currentTexOffsetX;
 	int currentTexOffsetY;
-	int currentTexOffset;		// raw value
+	int page;
 
 private:
 
@@ -120,7 +121,7 @@ private:
 	{
 		int texOffsetX;
 		int texOffsetY;
-		int texOffset;
+		int page;
 	};
 	std::vector<NodeAttribs> m_vecAttribs;
 };
diff --git a/Src/Graphics/New3D/New3D.cpp b/Src/Graphics/New3D/New3D.cpp
index e8bc099..44553f3 100644
--- a/Src/Graphics/New3D/New3D.cpp
+++ b/Src/Graphics/New3D/New3D.cpp
@@ -128,7 +128,11 @@ void CNew3D::RenderScene(int priority, bool alpha)
 				}
 				
 				if (mesh.textured) {
-					auto tex1 = m_texSheet.BindTexture(m_textureRAM, mesh.format, mesh.mirrorU, mesh.mirrorV, mesh.x + m.textureOffsetX, mesh.y + m.textureOffsetY, mesh.width, mesh.height);
+
+					int x, y;
+					CalcTexOffset(m.textureOffsetX, m.textureOffsetY, m.page, mesh.x, mesh.y, x, y);
+
+					auto tex1 = m_texSheet.BindTexture(m_textureRAM, mesh.format, mesh.mirrorU, mesh.mirrorV, x, y, mesh.width, mesh.height);
 					if (tex1) {
 						tex1->BindTexture();
 						tex1->SetWrapMode(mesh.mirrorU, mesh.mirrorV);
@@ -315,6 +319,7 @@ bool CNew3D::DrawModel(UINT32 modelAddr)
 	// update texture offsets
 	m->textureOffsetX = m_nodeAttribs.currentTexOffsetX;
 	m->textureOffsetY = m_nodeAttribs.currentTexOffsetY;
+	m->page = m_nodeAttribs.page;
 
 	if (!cached) {
 		CacheModel(m, modelAddress);
@@ -368,13 +373,13 @@ void CNew3D::DescendCullingNode(UINT32 addr)
 	if (!m_offset)	// Step 1.5+
 	{
 		tx = 32 * ((node[0x02] >> 7) & 0x3F);
-		ty = 32 * (node[0x02] & 0x3F) + ((node[0x02] & 0x4000) ? 1024 : 0);	// TODO: 5 or 6 bits for Y coord?
+		ty = 32 * (node[0x02] & 0x1F);
 
 		// apply texture offsets, else retain current ones
 		if ((node[0x02] & 0x8000))	{
 			m_nodeAttribs.currentTexOffsetX = tx;
 			m_nodeAttribs.currentTexOffsetY = ty;
-			m_nodeAttribs.currentTexOffset	= node[0x02] & 0x7FFF;
+			m_nodeAttribs.page = (node[0x02] & 0x4000) >> 14;
 		}
 	}
 
@@ -1153,5 +1158,22 @@ bool CNew3D::IsVROMModel(UINT32 modelAddr)
 	return modelAddr >= 0x100000;
 }
 
+void CNew3D::CalcTexOffset(int offX, int offY, int page, int x, int y, int& newX, int& newY)
+{
+	newX = (x + offX) & 2047;	// wrap around 2048, shouldn't be required
+
+	int oldPage = y / 1024;
+
+	y -= (oldPage * 1024);	// remove page from tex y
+
+	// calc newY with wrap around, wraps around in the same sheet, not into another memory sheet
+
+	newY = (y + offY) & 1023;
+
+	// add page to Y
+
+	newY += ((oldPage + page) & 1) * 1024;		// max page 0-1
+}
+
 } // New3D
 
diff --git a/Src/Graphics/New3D/New3D.h b/Src/Graphics/New3D/New3D.h
index f1dae85..110e88e 100644
--- a/Src/Graphics/New3D/New3D.h
+++ b/Src/Graphics/New3D/New3D.h
@@ -176,6 +176,8 @@ private:
 	bool IsDynamicModel(UINT32 *data);		// check if the model has a colour palette
 	bool IsVROMModel(UINT32 modelAddr);
 
+	void CalcTexOffset(int offX, int offY, int page, int x, int y, int& newX, int& newY);
+
 
 	/*
 	* Data