VideoSoftware: Improve fog range adjustment by using less magic and more comments.

Source/Core/VideoCommon/Src/BPMemory.h

@@ -686,8 +686,9 @@ union FogRangeKElement
 		u32 LO : 12;
 		u32 regid : 8;
 	};
+
 	// TODO: Which scaling coefficient should we use here? This is just a guess!
-	float GetValue(int i) { return (i ? HI : LO) / 32.f; }
+	float GetValue(int i) { return (i ? HI : LO) / 256.f; }
 	u32 HEX;
 };
 
@@ -697,7 +698,7 @@ struct FogRangeParams
 	{
 		struct
 		{
-			u32 Center : 10;
+			u32 Center : 10; // viewport center + 342
 			u32 Enabled : 1;
 			u32 unused : 13;
 			u32 regid : 8;

Source/Plugins/Plugin_VideoSoftware/Src/Tev.cpp

@@ -20,6 +20,7 @@
 #include "Tev.h"
 #include "EfbInterface.h"
 #include "TextureSampler.h"
+#include "XFMemLoader.h"
 #include "SWPixelEngine.h"
 #include "SWStatistics.h"
 #include "SWVideoConfig.h"
@@ -750,12 +751,19 @@ void Tev::Draw()
 
 		if(bpmem.fogRange.Base.Enabled)
 		{
-			// TODO: Check if this is correct (especially the magic values)
-			float offset = Position[0] - bpmem.fogRange.Base.Center + 324.f;
-			int index = 9 - std::abs(Position[0] - bpmem.fogRange.Base.Center + 324) / (162/5);
-			float k = bpmem.fogRange.K[index/2].GetValue(index%2);
-			float x_adjust = sqrt(offset*offset/162.f/162.f + k*k)/k;
-			ze *= x_adjust;
+			// TODO: This is untested and should definitely be checked against real hw.
+			// - No idea if offset is really normalized against the viewport width or against the projection matrix or yet something else
+			// - scaling of the "k" coefficient isn't clear either.
+
+			// First, calculate the offset from the viewport center (normalized to 0..1)
+			float offset = (Position[0] - (bpmem.fogRange.Base.Center - 342)) / (float)swxfregs.viewport.wd;
+			// Based on that, choose the index such that points which are far away from the z-axis use the 10th "k" value and such that central points use the first value.
+			int index = 9 - std::abs(offset) * 9.f;
+			index = (index < 0) ? 0 : (index > 9) ? 9 : 0; // TODO: Shouldn't be necessary!
+			// Look up coefficient... Seems like multiplying by 4 makes Fortune Street work properly (fog is too strong without the factor)
+			float k = bpmem.fogRange.K[index/2].GetValue(index%2) * 4.f;
+			float x_adjust = sqrt(offset*offset + k*k)/k;
+			ze *= x_adjust; // NOTE: This is basically dividing by a cosine (hidden behind GXInitFogAdjTable): 1/cos = c/b = sqrt(a^2+b^2)/b
 		}
 
 		ze -= bpmem.fog.c_proj_fsel.GetC();

Source/Plugins/Plugin_VideoSoftware/Src/TransformUnit.cpp

@@ -88,13 +88,13 @@ void TransformPosition(const InputVertexData *src, OutputVertexData *dst)
     const float* mat = (const float*)&swxfregs.posMatrices[src->posMtx * 4];    
     MultiplyVec3Mat34(src->position, mat, dst->mvPosition);
 
-    if (swxfregs.projection[6] == 0)
+    if (swxfregs.projection.type == GX_PERSPECTIVE)
     {
-        MultipleVec3Perspective(dst->mvPosition, swxfregs.projection, dst->projectedPosition);
+        MultipleVec3Perspective(dst->mvPosition, swxfregs.projection.rawProjection, dst->projectedPosition);
     }
     else
     {
-        MultipleVec3Ortho(dst->mvPosition, swxfregs.projection, dst->projectedPosition);
+        MultipleVec3Ortho(dst->mvPosition, swxfregs.projection.rawProjection, dst->projectedPosition);
     }
 }
 

Source/Plugins/Plugin_VideoSoftware/Src/XFMemLoader.h

@@ -85,6 +85,9 @@ struct Light
 #define LIGHTATTN_NONE 2
 #define LIGHTATTN_DIR 3
 
+#define GX_PERSPECTIVE  0
+#define GX_ORTHOGRAPHIC 1
+
 union LitChannel
 {
     struct
@@ -160,6 +163,12 @@ struct Viewport
 	float farZ;
 };
 
+struct Projection
+{
+	float rawProjection[6];
+	u32 type;                      // only GX_PERSPECTIVE or GX_ORTHOGRAPHIC are allowed
+};
+
 union TexMtxInfo
 {
     struct 
@@ -218,7 +227,7 @@ struct XFRegisters
     TXFMatrixIndexA MatrixIndexA;   // 0x1018
     TXFMatrixIndexB MatrixIndexB;   // 0x1019
     Viewport viewport;              // 0x101a - 0x101f
-    float projection[7];            // 0x1020 - 0x1026
+    Projection projection;          // 0x1020 - 0x1026
     u32 unk8[24];                   // 0x1027 - 0x103e
     u32 numTexGens;                 // 0x103f
     TexMtxInfo texMtxInfo[8];       // 0x1040 - 0x1047