Added new screenshot formats.

Added the ability to change the screenshot format with a new CVar:
r_screenshotFormat. This has four options: 0 (TGA), 1 (BMP), 2 (PNG),
and 3 (JPG). JPG quality can be selected with a new CVar:
r_screenshotJpgQuality. TGA is the default to preserve original behavior
from DOOM 3.

A new dependency on stb_image_write has been added. It has been
included. No additional configuration with CMake is required.

neo/renderer/RenderSystem_init.cpp

@@ -47,6 +47,9 @@ If you have questions concerning this license or the applicable additional terms
 #include "sys/win32/win_local.h"
 #endif
 
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include "stb_image_write.h"
+
 // functions that are not called every frame
 
 glconfig_t	glConfig;
@@ -230,6 +233,8 @@ idCVar r_scaleMenusTo43( "r_scaleMenusTo43", "1", CVAR_RENDERER | CVAR_ARCHIVE |
 // DG: the fscking patent has finally expired
 idCVar r_useCarmacksReverse( "r_useCarmacksReverse", "1", CVAR_RENDERER | CVAR_ARCHIVE | CVAR_BOOL, "Use Z-Fail (Carmack's Reverse) when rendering shadows" );
 idCVar r_useStencilOpSeparate( "r_useStencilOpSeparate", "1", CVAR_RENDERER | CVAR_ARCHIVE | CVAR_BOOL, "Use glStencilOpSeparate() (if available) when rendering shadows" );
+idCVar r_screenshotFormat("r_screenshotFormat", "0", CVAR_RENDERER | CVAR_ARCHIVE | CVAR_INTEGER, "Screenshot format. 0 = TGA (default), 1 = BMP, 2 = PNG, 3 = JPG");
+idCVar r_screenshotJpgQuality("r_screenshotJpgQuality", "75", CVAR_RENDERER | CVAR_ARCHIVE | CVAR_INTEGER, "Screenshot quality for JPG images (0-100)");
 
 // define qgl functions
 #define QGLPROC(name, rettype, args) rettype (APIENTRYP q##name) args;
@@ -1249,6 +1254,18 @@ void R_ReadTiledPixels( int width, int height, byte *buffer, renderView_t *ref =
 	glConfig.vidHeight = oldHeight;
 }
 
+/*
+==================
+WriteScreenshot
+
+Callback to each screenshot function
+==================
+*/
+void WriteScreenshot(void* context, void* data, int size)
+{
+	idFile* f = (idFile*)context;
+	f->Write(data, size);
+}
 
 /*
 ==================
@@ -1262,66 +1279,80 @@ If ref == NULL, session->updateScreen will be used
 ==================
 */
 void idRenderSystemLocal::TakeScreenshot( int width, int height, const char *fileName, int blends, renderView_t *ref ) {
-	byte		*buffer;
-	int			i, j, c, temp;
+	byte		*buffer, *flippedBuffer;
+	int			i, j, k;
 
 	takingScreenshot = true;
 
 	int	pix = width * height;
 
-	buffer = (byte *)R_StaticAlloc(pix*3 + 18);
-	memset (buffer, 0, 18);
+	buffer = (byte *)R_StaticAlloc(pix*3);
+	flippedBuffer = (byte*)R_StaticAlloc(pix*3);
 
 	if ( blends <= 1 ) {
-		R_ReadTiledPixels( width, height, buffer + 18, ref );
+		R_ReadTiledPixels( width, height, buffer, ref );
 	} else {
 		unsigned short *shortBuffer = (unsigned short *)R_StaticAlloc(pix*2*3);
-		memset (shortBuffer, 0, pix*2*3);
+		memset( shortBuffer, 0, pix*2*3 );
 
 		// enable anti-aliasing jitter
 		r_jitter.SetBool( true );
 
 		for ( i = 0 ; i < blends ; i++ ) {
-			R_ReadTiledPixels( width, height, buffer + 18, ref );
+			R_ReadTiledPixels( width, height, buffer, ref );
 
 			for ( j = 0 ; j < pix*3 ; j++ ) {
-				shortBuffer[j] += buffer[18+j];
+				shortBuffer[j] += buffer[j];
 			}
 		}
 
 		// divide back to bytes
 		for ( i = 0 ; i < pix*3 ; i++ ) {
-			buffer[18+i] = shortBuffer[i] / blends;
+			buffer[i] = shortBuffer[i] / blends;
 		}
 
 		R_StaticFree( shortBuffer );
 		r_jitter.SetBool( false );
 	}
 
-	// fill in the header (this is vertically flipped, which qglReadPixels emits)
-	buffer[2] = 2;		// uncompressed type
-	buffer[12] = width & 255;
-	buffer[13] = width >> 8;
-	buffer[14] = height & 255;
-	buffer[15] = height >> 8;
-	buffer[16] = 24;	// pixel size
-
-	// swap rgb to bgr
-	c = 18 + width * height * 3;
-	for (i=18 ; i<c ; i+=3) {
-		temp = buffer[i];
-		buffer[i] = buffer[i+2];
-		buffer[i+2] = temp;
+	// The buffer is upside down, we need to flip it the right way.
+	for (i = 0; i < width; i++) {
+		for (j = 0; j < height; j++) {
+			for (k = 0; k < 3; k++) {
+				flippedBuffer[(i + j * width) * 3 + k] = buffer[(i + (height - 1 - j) * width) * 3 + k];
+			}
+		}
 	}
 
-	// _D3XP adds viewnote screenie save to cdpath
-	if ( strstr( fileName, "viewnote" ) ) {
-		fileSystem->WriteFile( fileName, buffer, c, "fs_cdpath" );
-	} else {
-		fileSystem->WriteFile( fileName, buffer, c );
+	
+	idFile* f;
+	if (strstr(fileName, "viewnote")) {
+		f = fileSystem->OpenFileWrite( fileName, "fs_cdpath" );
 	}
+	else {
+		f = fileSystem->OpenFileWrite( fileName );
+	}
+
+	switch (cvarSystem->GetCVarInteger( "r_screenshotFormat" ))
+	{
+		default:
+			stbi_write_tga_to_func( WriteScreenshot, f, width, height, 3, flippedBuffer );
+			break;
+		case 1:
+			stbi_write_bmp_to_func( WriteScreenshot, f, width, height, 3, flippedBuffer );
+			break;
+		case 2:
+			stbi_write_png_to_func( WriteScreenshot, f, width, height, 3, flippedBuffer, 3 * width );
+			break;
+		case 3:
+			stbi_write_jpg_to_func( WriteScreenshot, f, width, height, 3, flippedBuffer, idMath::ClampInt(0, 100, cvarSystem->GetCVarInteger("r_screenshotJpgQuality")) );
+			break;
+	}
+
+	fileSystem->CloseFile(f);
 
 	R_StaticFree( buffer );
+	R_StaticFree( flippedBuffer );
 
 	takingScreenshot = false;
 
@@ -1344,6 +1375,8 @@ void R_ScreenshotFilename( int &lastNumber, const char *base, idStr &fileName )
 	bool fsrestrict = cvarSystem->GetCVarBool( "fs_restrict" );
 	cvarSystem->SetCVarBool( "fs_restrict", false );
 
+	int format = cvarSystem->GetCVarInteger("r_screenshotFormat");
+
 	lastNumber++;
 	if ( lastNumber > 99999 ) {
 		lastNumber = 99999;
@@ -1361,7 +1394,21 @@ void R_ScreenshotFilename( int &lastNumber, const char *base, idStr &fileName )
 		frac -= d*10;
 		e = frac;
 
-		sprintf( fileName, "%s%i%i%i%i%i.tga", base, a, b, c, d, e );
+		switch (format) {
+			default:
+				sprintf(fileName, "%s%i%i%i%i%i.tga", base, a, b, c, d, e);
+				break;
+			case 1:
+				sprintf(fileName, "%s%i%i%i%i%i.bmp", base, a, b, c, d, e);
+				break;
+			case 2:
+				sprintf(fileName, "%s%i%i%i%i%i.png", base, a, b, c, d, e);
+				break;
+			case 3:
+				sprintf(fileName, "%s%i%i%i%i%i.jpg", base, a, b, c, d, e);
+				break;
+		}
+		
 		if ( lastNumber == 99999 ) {
 			break;
 		}