- Reinstated the off-by-one check in D3DFB from r399. I thought I could get by

at just fixing it at a specific value, since the supply of SM14 cards isn't
  all that diverse and all from ATI, but apparently Radeon 8500s and 9000s
  have different precision levels in their pixel shaders. See bug report
  <http://forum.zdoom.org/viewtopic.php?p=444523>
- Removed unused variables FBFormat and PalFormat.

SVN r1901 (trunk)

docs/rh-log.txt

@@ -1,3 +1,10 @@
+October 8, 2009
+- Reinstated the off-by-one check in D3DFB from r399. I thought I could get by
+  at just fixing it at a specific value, since the supply of SM14 cards isn't
+  all that diverse and all from ATI, but apparently Radeon 8500s and 9000s
+  have different precision levels in their pixel shaders. See bug report
+  <http://forum.zdoom.org/viewtopic.php?p=444523>
+
 October 8, 2009  (Changes by Graf Zahl)
 - Added a PainThreshold actor property.
 - fixed: Teleport_EndGame did not set the end sequence name properly.

src/win32/fb_d3d9.cpp

@@ -281,8 +281,6 @@ D3DFB::D3DFB (int width, int height, bool fullscreen)
 	GammaShader = NULL;
 	BlockSurface[0] = NULL;
 	BlockSurface[1] = NULL;
-	FBFormat = D3DFMT_UNKNOWN;
-	PalFormat = D3DFMT_UNKNOWN;
 	VSync = vid_vsync;
 	BlendingRect.left = 0;
 	BlendingRect.top = 0;
@@ -298,6 +296,7 @@ D3DFB::D3DFB (int width, int height, bool fullscreen)
 	QuadExtra = new BufferedQuad[MAX_QUAD_BATCH];
 	Packs = NULL;
 	PixelDoubling = 0;
+	SkipAt = -1;
 
 	Gamma = 1.0;
 	FlashColor0 = 0;
@@ -787,7 +786,6 @@ bool D3DFB::CreatePaletteTexture ()
 	{
 		return false;
 	}
-	PalFormat = D3DFMT_A8R8G8B8;
 	return true;
 }
 
@@ -1277,28 +1275,144 @@ void D3DFB::UpdateGammaTexture(float igamma)
 	}
 }
 
+//==========================================================================
+//
+// D3DFB :: DoOffByOneCheck
+//
+// Pixel Shader 1.x does not have enough precision to properly map a "color"
+// from the source texture to an index in the palette texture. The best we
+// can do is use 255 pixels of the palette and get the 256th from the
+// texture border color. This routine determines which pixel of the texture
+// is skipped so that we don't use it for palette data.
+//
+//==========================================================================
+
+void D3DFB::DoOffByOneCheck ()
+{
+	IDirect3DSurface9 *savedrendertarget;
+	IDirect3DSurface9 *testsurf, *readsurf;
+	D3DLOCKED_RECT lockrect;
+	RECT testrect = { 0, 0, 256, 1 };
+	float texright = 256.f / float(FBWidth);
+	float texbot = 1.f / float(FBHeight);
+	FBVERTEX verts[4] =
+	{
+		{ -0.5f,  -0.5f, 0.5f, 1.f, 0, ~0,      0.f,    0.f },
+		{ 255.5f, -0.5f, 0.5f, 1.f, 0, ~0, texright,    0.f },
+		{ 255.5f,  0.5f, 0.5f, 1.f, 0, ~0, texright, texbot },
+		{ -0.5f,   0.5f, 0.5f, 1.f, 0, ~0,      0.f, texbot }
+	};
+	int i, c;
+
+	if (SkipAt >= 0)
+	{
+		return;
+	}
+
+	// Create an easily recognizable R3G3B2 palette.
+	if (SUCCEEDED(PaletteTexture->LockRect(0, &lockrect, NULL, 0)))
+	{
+		BYTE *pal = (BYTE *)(lockrect.pBits);
+		for (i = 0; i < 256; ++i)
+		{
+			pal[i*4+0] = (i & 0x03) << 6;		// blue
+			pal[i*4+1] = (i & 0x1C) << 3;		// green
+			pal[i*4+2] = (i & 0xE0);			// red;
+			pal[i*4+3] = 255;
+		}
+		PaletteTexture->UnlockRect (0);
+	}
+	else
+	{
+		return;
+	}
+	// Prepare a texture with values 0-256.
+	if (SUCCEEDED(FBTexture->LockRect(0, &lockrect, &testrect, 0)))
+	{
+		for (i = 0; i < 256; ++i)
+		{
+			((BYTE *)lockrect.pBits)[i] = i;
+		}
+		FBTexture->UnlockRect(0);
+	}
+	else
+	{
+		return;
+	}
+	// Create a render target that we can draw it to.
+	if (FAILED(D3DDevice->GetRenderTarget(0, &savedrendertarget)))
+	{
+		return;
+	}
+	if (FAILED(D3DDevice->CreateRenderTarget(256, 1, D3DFMT_A8R8G8B8, D3DMULTISAMPLE_NONE, 0, FALSE, &testsurf, NULL)))
+	{
+		return;
+	}
+	if (FAILED(D3DDevice->CreateOffscreenPlainSurface(256, 1, D3DFMT_A8R8G8B8, D3DPOOL_SYSTEMMEM, &readsurf, NULL)))
+	{
+		testsurf->Release();
+		return;
+	}
+	if (FAILED(D3DDevice->SetRenderTarget(0, testsurf)))
+	{
+		testsurf->Release();
+		readsurf->Release();
+		return;
+	}
+	// Write it to the render target using the pixel shader.
+	D3DDevice->BeginScene();
+	D3DDevice->SetTexture(0, FBTexture);
+	D3DDevice->SetTexture(1, PaletteTexture);
+	D3DDevice->SetFVF(D3DFVF_FBVERTEX);
+	D3DDevice->SetPixelShader(Shaders[SHADER_NormalColorPal]);
+	SetConstant(PSCONST_PaletteMod, 1.f, 0.5f / 256.f, 0, 0);
+	D3DDevice->DrawPrimitiveUP(D3DPT_TRIANGLEFAN, 2, verts, sizeof(FBVERTEX));
+	D3DDevice->EndScene();
+	D3DDevice->SetRenderTarget(0, savedrendertarget);
+	savedrendertarget->Release();
+	// Now read it back and see where it skips an entry
+	if (SUCCEEDED(D3DDevice->GetRenderTargetData(testsurf, readsurf)) &&
+		SUCCEEDED(readsurf->LockRect(&lockrect, &testrect, D3DLOCK_READONLY)))
+	{
+		const BYTE *pix = (const BYTE *)lockrect.pBits;
+		for (i = 0; i < 256; ++i, pix += 4)
+		{
+			c = (pix[0] >> 6) |					// blue
+				((pix[1] >> 5) << 2) |			// green
+				((pix[2] >> 5) << 5);			// red
+			if (c != i)
+			{
+				break;
+			}
+		}
+	}
+	readsurf->UnlockRect();
+	readsurf->Release();
+	testsurf->Release();
+	SkipAt = i;
+}
+
 void D3DFB::UploadPalette ()
 {
 	D3DLOCKED_RECT lockrect;
 
+	if (SkipAt < 0)
+	{
+		if (SM14)
+		{
+			DoOffByOneCheck();
+		}
+		else
+		{
+			SkipAt = 256;
+		}
+	}
 	if (SUCCEEDED(PaletteTexture->LockRect(0, &lockrect, NULL, 0)))
 	{
 		BYTE *pix = (BYTE *)lockrect.pBits;
-		int i, skipat;
+		int i;
 
-		// It is impossible to get the Radeon 9000 to do the proper palette
-		// lookup. It *will* skip at least one entry in the palette. So we
-		// let it and have it look at the texture border color for color 255.
-		// I assume that every other card based on a related graphics chipset
-		// is similarly affected, which basically means that all Shader Model
-		// 1.4 cards suffer from this problem, since they all use some variant
-		// of the ATI R200.
-		//
-		// [Oh, gee. Looking over the old documentation, I guess this is
-		// documented that PS 1.x cards don't have a lot of precision.]
-		skipat = SM14 ? 256 - 8 : 256;
-
-		for (i = 0; i < skipat; ++i, pix += 4)
+		for (i = 0; i < SkipAt; ++i, pix += 4)
 		{
 			pix[0] = SourcePalette[i].b;
 			pix[1] = SourcePalette[i].g;

src/win32/win32iface.h

@@ -338,6 +338,7 @@ private:
 	bool CreatePaletteTexture();
 	bool CreateGammaTexture();
 	bool CreateVertexes();
+	void DoOffByOneCheck();
 	void UploadPalette();
 	void UpdateGammaTexture(float igamma);
 	void FillPresentParameters (D3DPRESENT_PARAMETERS *pp, bool fullscreen, bool vsync);
@@ -391,14 +392,13 @@ private:
 	int FlashAmount;
 	int TrueHeight;
 	int PixelDoubling;
+	int SkipAt;
 	int LBOffsetI;
 	float LBOffset;
 	float Gamma;
 	bool UpdatePending;
 	bool NeedPalUpdate;
 	bool NeedGammaUpdate;
-	D3DFORMAT FBFormat;
-	D3DFORMAT PalFormat;
 	int FBWidth, FBHeight;
 	bool VSync;
 	RECT BlendingRect;