Fixed overbright screenshots with hardware gamma off

When render buffers are used to apply gamma/brightness/contrast screenshots should not use PNG gamma correction

src/gl/scene/gl_scene.cpp

@@ -969,7 +969,7 @@ void GLSceneDrawer::WriteSavePic (player_t *player, FileWriter *file, int width,
 
 	uint8_t * scr = (uint8_t *)M_Malloc(width * height * 3);
 	glReadPixels(0,0,width, height,GL_RGB,GL_UNSIGNED_BYTE,scr);
-	M_CreatePNG (file, scr + ((height-1) * width * 3), NULL, SS_RGB, width, height, -width*3);
+	M_CreatePNG (file, scr + ((height-1) * width * 3), NULL, SS_RGB, width, height, -width * 3, Gamma);
 	M_Free(scr);
 }
 

src/gl/system/gl_framebuffer.cpp

@@ -487,7 +487,7 @@ void OpenGLFrameBuffer::FillSimplePoly(FTexture *texture, FVector2 *points, int
 //
 //===========================================================================
 
-void OpenGLFrameBuffer::GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type)
+void OpenGLFrameBuffer::GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type, float &gamma)
 {
 	const auto &viewport = GLRenderer->mOutputLetterbox;
 
@@ -527,6 +527,10 @@ void OpenGLFrameBuffer::GetScreenshotBuffer(const uint8_t *&buffer, int &pitch,
 	pitch = -w*3;
 	color_type = SS_RGB;
 	buffer = ScreenshotBuffer + w * 3 * (h - 1);
+
+	// Screenshot should not use gamma correction if it was already applied to rendered image
+	EXTERN_CVAR(Bool, fullscreen);
+	gamma = 1 == vid_hwgamma || (2 == vid_hwgamma && !fullscreen) ? 1.0f : Gamma;
 }
 
 //===========================================================================

src/gl/system/gl_framebuffer.h

@@ -51,7 +51,7 @@ public:
 	// Retrieves a buffer containing image data for a screenshot.
 	// Hint: Pitch can be negative for upside-down images, in which case buffer
 	// points to the last row in the buffer, which will be the first row output.
-	virtual void GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type);
+	virtual void GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type, float &gamma) override;
 
 	// Releases the screenshot buffer.
 	virtual void ReleaseScreenshotBuffer();

src/gl/system/gl_swframebuffer.cpp

@@ -1671,15 +1671,15 @@ void OpenGLSWFrameBuffer::SetBlendingRect(int x1, int y1, int x2, int y2)
 //
 //==========================================================================
 
-void OpenGLSWFrameBuffer::GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type)
+void OpenGLSWFrameBuffer::GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type, float &gamma)
 {
-	Super::GetScreenshotBuffer(buffer, pitch, color_type);
+	Super::GetScreenshotBuffer(buffer, pitch, color_type, gamma);
 	/*
 	LockedRect lrect;
 
 	if (!Accel2D)
 	{
-		Super::GetScreenshotBuffer(buffer, pitch, color_type);
+		Super::GetScreenshotBuffer(buffer, pitch, color_type, gamma);
 		return;
 	}
 	buffer = nullptr;
@@ -1702,6 +1702,7 @@ void OpenGLSWFrameBuffer::GetScreenshotBuffer(const uint8_t *&buffer, int &pitch
 			buffer = (const uint8_t *)lrect.pBits;
 			pitch = lrect.Pitch;
 			color_type = SS_BGRA;
+			gamma = Gamma;
 		}
 	}
 	*/

src/gl/system/gl_swframebuffer.h

@@ -44,7 +44,7 @@ public:
 	int GetPageCount() override;
 	void SetVSync(bool vsync) override;
 	void NewRefreshRate() override;
-	void GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type) override;
+	void GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type, float &gamma) override;
 	void ReleaseScreenshotBuffer() override;
 	void SetBlendingRect(int x1, int y1, int x2, int y2) override;
 	bool Begin2D(bool copy3d) override;

src/m_misc.cpp

@@ -521,11 +521,11 @@ void WritePCXfile (FileWriter *file, const uint8_t *buffer, const PalEntry *pale
 // WritePNGfile
 //
 void WritePNGfile (FileWriter *file, const uint8_t *buffer, const PalEntry *palette,
-				   ESSType color_type, int width, int height, int pitch)
+				   ESSType color_type, int width, int height, int pitch, float gamma)
 {
 	char software[100];
 	mysnprintf(software, countof(software), GAMENAME " %s", GetVersionString());
-	if (!M_CreatePNG (file, buffer, palette, color_type, width, height, pitch) ||
+	if (!M_CreatePNG (file, buffer, palette, color_type, width, height, pitch, gamma) ||
 		!M_AppendPNGText (file, "Software", software) ||
 		!M_FinishPNG (file))
 	{
@@ -626,8 +626,9 @@ void M_ScreenShot (const char *filename)
 	const uint8_t *buffer;
 	int pitch;
 	ESSType color_type;
+	float gamma;
 
-	screen->GetScreenshotBuffer(buffer, pitch, color_type);
+	screen->GetScreenshotBuffer(buffer, pitch, color_type, gamma);
 	if (buffer != NULL)
 	{
 		PalEntry palette[256];
@@ -651,7 +652,7 @@ void M_ScreenShot (const char *filename)
 		else
 		{
 			WritePNGfile(file, buffer, palette, color_type,
-				screen->GetWidth(), screen->GetHeight(), pitch);
+				screen->GetWidth(), screen->GetHeight(), pitch, gamma);
 		}
 		delete file;
 		screen->ReleaseScreenshotBuffer();

src/m_png.cpp

@@ -132,7 +132,7 @@ CVAR(Float, png_gamma, 0.f, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
 //==========================================================================
 
 bool M_CreatePNG (FileWriter *file, const uint8_t *buffer, const PalEntry *palette,
-				  ESSType color_type, int width, int height, int pitch)
+				  ESSType color_type, int width, int height, int pitch, float gamma)
 {
 	uint8_t work[8 +				// signature
 			  12+2*4+5 +		// IHDR
@@ -157,7 +157,7 @@ bool M_CreatePNG (FileWriter *file, const uint8_t *buffer, const PalEntry *palet
 	MakeChunk (ihdr, MAKE_ID('I','H','D','R'), 2*4+5);
 
 	// Assume a display exponent of 2.2 (100000/2.2 ~= 45454.5)
-	*gama = BigLong (int (45454.5f * (png_gamma == 0.f ? Gamma : png_gamma)));
+	*gama = BigLong (int (45454.5f * (png_gamma == 0.f ? gamma : png_gamma)));
 	MakeChunk (gama, MAKE_ID('g','A','M','A'), 4);
 
 	if (color_type == SS_PAL)

src/m_png.h

@@ -46,7 +46,7 @@ class FileWriter;
 // This function writes the PNG signature and the IHDR, gAMA, PLTE, and IDAT
 // chunks.
 bool M_CreatePNG (FileWriter *file, const uint8_t *buffer, const PalEntry *pal,
-				  ESSType color_type, int width, int height, int pitch);
+				  ESSType color_type, int width, int height, int pitch, float gamma);
 
 // Creates a grayscale 1x1 PNG file. Used for savegames without savepics.
 bool M_CreateDummyPNG (FileWriter *file);

src/swrenderer/r_swrenderer.cpp

@@ -225,7 +225,7 @@ void FSoftwareRenderer::WriteSavePic (player_t *player, FileWriter *file, int wi
 		r_viewwindow = mScene.MainThread()->Viewport->viewwindow;
 	}
 	screen->GetFlashedPalette (palette);
-	M_CreatePNG (file, pic->GetBuffer(), palette, SS_PAL, width, height, pic->GetPitch());
+	M_CreatePNG (file, pic->GetBuffer(), palette, SS_PAL, width, height, pic->GetPitch(), Gamma);
 	pic->Unlock ();
 	delete pic;
 }
@@ -399,4 +399,4 @@ uint32_t FSoftwareRenderer::GetCaps()
 		FlagSet |= RFF_COLORMAP;
 
 	return (uint32_t)FlagSet;
-}
+}

src/v_video.cpp

@@ -329,12 +329,13 @@ void DCanvas::Dim (PalEntry color)
 //
 //==========================================================================
 
-void DCanvas::GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type)
+void DCanvas::GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type, float &gamma)
 {
 	Lock(true);
 	buffer = GetBuffer();
 	pitch = IsBgra() ? GetPitch() * 4 : GetPitch();
 	color_type = IsBgra() ? SS_BGRA : SS_PAL;
+	gamma = Gamma;
 }
 
 //==========================================================================

src/v_video.h

@@ -256,7 +256,7 @@ public:
 	// Retrieves a buffer containing image data for a screenshot.
 	// Hint: Pitch can be negative for upside-down images, in which case buffer
 	// points to the last row in the buffer, which will be the first row output.
-	virtual void GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type);
+	virtual void GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type, float &gamma);
 
 	// Releases the screenshot buffer.
 	virtual void ReleaseScreenshotBuffer();

src/win32/fb_d3d9.cpp

@@ -1755,13 +1755,13 @@ void D3DFB::SetBlendingRect(int x1, int y1, int x2, int y2)
 //
 //==========================================================================
 
-void D3DFB::GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type)
+void D3DFB::GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type, float &gamma)
 {
 	D3DLOCKED_RECT lrect;
 
 	if (!Accel2D)
 	{
-		Super::GetScreenshotBuffer(buffer, pitch, color_type);
+		Super::GetScreenshotBuffer(buffer, pitch, color_type, gamma);
 		return;
 	}
 	buffer = NULL;
@@ -1784,6 +1784,7 @@ void D3DFB::GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &col
 			buffer = (const uint8_t *)lrect.pBits;
 			pitch = lrect.Pitch;
 			color_type = SS_BGRA;
+			gamma = Gamma;
 		}
 	}
 }

src/win32/win32swiface.h

@@ -124,7 +124,7 @@ public:
 	bool PaintToWindow ();
 	void SetVSync (bool vsync);
 	void NewRefreshRate();
-	void GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type);
+	void GetScreenshotBuffer(const uint8_t *&buffer, int &pitch, ESSType &color_type, float &gamma) override;
 	void ReleaseScreenshotBuffer();
 	void SetBlendingRect (int x1, int y1, int x2, int y2);
 	bool Begin2D (bool copy3d);