Add toggle to disable gamma 'correction' of linear data. Closes #58

* The explanation is in the FAQ but the short explanation is that most
  data e.g. normal maps are conventionally displayed as if they contained
  SRGB data, so RenderDoc does the same so things look as expected.

renderdoc/driver/d3d11/d3d11_analyse.cpp

@@ -1396,6 +1396,7 @@ void D3D11DebugManager::PickPixel(ResourceId texture, uint32_t x, uint32_t y, ui
 
 		texDisplay.Red = texDisplay.Green = texDisplay.Blue = texDisplay.Alpha = true;
 		texDisplay.HDRMul = -1.0f;
+		texDisplay.linearDisplayAsGamma = true;
 		texDisplay.mip = mip;
 		texDisplay.CustomShader = ResourceId();
 		texDisplay.sliceFace = sliceFace;
@@ -2048,6 +2049,7 @@ ResourceId D3D11DebugManager::ApplyCustomShader(ResourceId shader, ResourceId te
 	disp.texid = texid;
 	disp.lightBackgroundColour = disp.darkBackgroundColour = FloatVector(0,0,0,0);
 	disp.HDRMul = -1.0f;
+	disp.linearDisplayAsGamma = true;
 	disp.mip = mip;
 	disp.overlay = eTexOverlay_None;
 	disp.rangemin = 0.0f;

renderdoc/driver/d3d11/d3d11_debug.cpp

@@ -3464,7 +3464,7 @@ bool D3D11DebugManager::RenderTexture(TextureDisplay cfg)
 		pixelData.OutputDisplayFormat |= TEXDISPLAY_SINT_TEX;
 		srvOffset = 20;
 	}
-	if(!IsSRGBFormat(details.texFmt))
+	if(!IsSRGBFormat(details.texFmt) && cfg.linearDisplayAsGamma)
 	{
 		pixelData.OutputDisplayFormat |= TEXDISPLAY_GAMMA_CURVE;
 	}

renderdoc/driver/gl/gl_debug.cpp

@@ -198,6 +198,7 @@ void GLReplay::PickPixel(ResourceId texture, uint32_t x, uint32_t y, uint32_t sl
 
 		texDisplay.Red = texDisplay.Green = texDisplay.Blue = texDisplay.Alpha = true;
 		texDisplay.HDRMul = -1.0f;
+		texDisplay.linearDisplayAsGamma = true;
 		texDisplay.mip = mip;
 		texDisplay.CustomShader = ResourceId();
 		texDisplay.sliceFace = sliceFace;

renderdoc/replay/control_types.h

@@ -60,6 +60,7 @@ struct TextureDisplay
 	float scale;
 	bool32 Red, Green, Blue, Alpha;
 	float HDRMul;
+	bool32 linearDisplayAsGamma;
 	ResourceId CustomShader;
 	uint32_t mip;
 	uint32_t sliceFace;

renderdoc/replay/replay_output.cpp

@@ -361,6 +361,7 @@ bool ReplayOutput::Display()
 		disp.Red = disp.Green = disp.Blue = true;
 		disp.Alpha = false;
 		disp.HDRMul = -1.0f;
+		disp.linearDisplayAsGamma = true;
 		disp.mip = 0;
 		disp.CustomShader = ResourceId();
 		disp.texid = m_pDevice->GetLiveID(m_Thumbnails[i].texture);