Related FOG changes:

* revert back to proper upscale mantissa of parameters A and C
* properly downscale magnitude to 0.24 bits instead than ≡0.23
* Z Eyespace conversion for projection by original patent concept

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@6463 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Core/VideoCommon/Src/BPMemory.h

@@ -650,7 +650,7 @@ union FogParam0
 
     float GetA() {
 		union { u32 i; float f; } dummy;
-        dummy.i = ((u32)sign<<31)|((u32)exponent<<23)|((u32)mantissa * 0x7FFFFF / 0x7FF); // scale mantissa from 11 to 23 bits
+        dummy.i = ((u32)sign << 31) | ((u32)exponent << 23) | ((u32)mantissa << 12); // scale mantissa from 11 to 23 bits
 		return dummy.f;
 	}
 
@@ -671,7 +671,7 @@ union FogParam3
     // amount to subtract from eyespacez after range adjustment
     float GetC() { 
 		union { u32 i; float f; } dummy;
-		dummy.i = ((u32)c_sign << 31) | ((u32)c_exp << 23) | ((u32)c_mant * 0x7FFFFF / 0x7FF); // scale mantissa from 11 to 23 bits
+		dummy.i = ((u32)c_sign << 31) | ((u32)c_exp << 23) | ((u32)c_mant << 12); // scale mantissa from 11 to 23 bits
 		return dummy.f;
 	}
 

Source/Core/VideoCommon/Src/PixelShaderGen.cpp

@@ -1310,16 +1310,21 @@ static void WriteFog(char *&p)
 	if (bpmem.fog.c_proj_fsel.proj == 0) 
 	{
 		// perspective
-		// ze = A/(B - Zs)
-		WRITE (p, "  float ze = "I_FOG"[1].x / ("I_FOG"[1].y - zCoord);\n");
+		// ze = A/(B - (Zs >> B_SHF)
+		WRITE (p, "  float ze = "I_FOG"[1].x / ("I_FOG"[1].y - (zCoord / "I_FOG"[1].w));\n");
 	}
 	else
 	{
 		// orthographic
-		// ze = a*Zs
+		// ze = a*Zs	(here, no B_SHF)
 		WRITE (p, "  float ze = "I_FOG"[1].x * zCoord;\n");
 	}
 	
+	// stuff to do!
+	// here, where we'll have to add/handle x range adjustment (if related BP register it's enabled)
+	// x_adjust = sqrt((x-center)^2 + k^2)/k
+	// ze *= x_adjust
+
 	WRITE (p, "  float fog = saturate(ze - "I_FOG"[1].z);\n");
 
 	if(bpmem.fog.c_proj_fsel.fsel > 3)

Source/Core/VideoCommon/Src/PixelShaderManager.cpp

@@ -201,9 +201,11 @@ void PixelShaderManager::SetConstants()
 	{
 		if(!g_ActiveConfig.bDisableFog)
 		{
-			float a = bpmem.fog.a.GetA() * ((float)(1 << (bpmem.fog.b_shift - 1)));
-			float b = ((float)bpmem.fog.b_magnitude / 8388638) * ((float)(1 << (bpmem.fog.b_shift - 1)));
-			SetPSConstant4f(C_FOG + 1, a, b, bpmem.fog.c_proj_fsel.GetC(), 0);
+			//downscale magnitude to 0.24 bits
+			float b = (float)bpmem.fog.b_magnitude / 0xFFFFFF;
+
+			float b_shf = (float)(1 << bpmem.fog.b_shift);
+			SetPSConstant4f(C_FOG + 1, bpmem.fog.a.GetA(), b, bpmem.fog.c_proj_fsel.GetC(), b_shf);
 		}
 		else
 		{

Source/Plugins/Plugin_VideoSoftware/Src/Tev.cpp

@@ -718,18 +718,26 @@ void Tev::Draw()
 		if (bpmem.fog.c_proj_fsel.proj == 0)
 		{
 			// perspective
-			// ze = A/(B - Zs)
+			// ze = A/(B - (Zs >> B_SHF))
 			s32 denom = bpmem.fog.b_magnitude - (Position[2] >> bpmem.fog.b_shift);
-			ze = bpmem.fog.a.GetA() / (float)denom;
+			//in addition downscale magnitude and zs to 0.24 bits
+			ze = (bpmem.fog.a.GetA() * 16777215.0f) / (float)denom;
 		} 
 		else 
 		{
 			// orthographic
 			// ze = a*Zs
-			ze = bpmem.fog.a.GetA() / (float)Position[2];
+			//in addition downscale zs to 0.24 bits
+			ze = bpmem.fog.a.GetA() * ((float)Position[2] / 16777215.0f);
+
 		}
 
-		ze = (ze * (float)0xffffff) - bpmem.fog.c_proj_fsel.GetC();
+		// stuff to do!
+		// here, where we'll have to add/handle x range adjustment (if related BP register it's enabled)
+		// x_adjust = sqrt((x-center)^2 + k^2)/k
+		// ze *= x_adjust
+
+		ze -= bpmem.fog.c_proj_fsel.GetC();
 
 		// clamp 0 to 1
 		float fog = (ze<0.0f) ? 0.0f : ((ze>1.0f) ? 1.0f : ze);
@@ -744,11 +752,11 @@ void Tev::Draw()
 				break;
 			case 6: // backward exp
 				fog = 1.0f - fog;
-				fog = 1.0f - pow(2.0f, -8.0f * fog);
+				fog = pow(2.0f, -8.0f * fog);
 				break;
 			case 7: // backward exp2
 				fog = 1.0f - fog;
-				fog = 1.0f - pow(2.0f, -8.0f * fog * fog);
+				fog = pow(2.0f, -8.0f * fog * fog);
 				break;
 		}