ref: add new special rendermode that specifically used for modulate mode in engine's ScreenFade

engine/ref_api.h

@@ -67,6 +67,10 @@ GNU General Public License for more details.
 #define FWORLD_WATERALPHA		BIT( 2 )
 #define FWORLD_HAS_DELUXEMAP		BIT( 3 )
 
+// special rendermode for screenfade modulate
+// (probably will be expanded at some point)
+#define kRenderScreenFadeModulate 0x1000
+
 typedef enum
 {
 	DEMO_INACTIVE = 0,

ref/gl/gl_backend.c

@@ -417,6 +417,10 @@ void GL_SetRenderMode( int mode )
 		pglDisable( GL_ALPHA_TEST );
 		pglBlendFunc( GL_SRC_ALPHA, GL_ONE );
 		break;
+	case kRenderScreenFadeModulate:
+		pglEnable( GL_BLEND );
+		pglDisable( GL_ALPHA_TEST );
+		pglBlendFunc( GL_ZERO, GL_SRC_COLOR );
 	}
 }
 

ref/soft/r_draw.c

@@ -165,11 +165,15 @@ void R_DrawStretchPicImplementation( int x, int y, int w, int h, int s1, int t1,
 					pixel_t screen = dest[u];
 					dest[u] = vid.addmap[(src & 0xff00)|(screen>>8)] << 8 | (screen & 0xff) | ((src & 0xff) >> 0);
 				}
+				else if( vid.rendermode == kRenderScreenFadeModulate )
+				{
+					pixel_t screen = dest[u];
+					dest[u] = BLEND_COLOR( screen, vid.color );
+				}
 				else if( alpha < 7) // && (vid.rendermode == kRenderTransAlpha || vid.rendermode == kRenderTransTexture ) )
 				{
 					pixel_t screen = dest[u]; //  | 0xff & screen & src ;
-					dest[u] = BLEND_ALPHA( alpha, src, screen);//vid.alphamap[( alpha << 16)|(src & 0xff00)|(screen>>8)] << 8 | (screen & 0xff) >> 3 | ((src & 0xff) >> 3);
-
+					dest[u] = BLEND_ALPHA( alpha, src, screen );//vid.alphamap[( alpha << 16)|(src & 0xff00)|(screen>>8)] << 8 | (screen & 0xff) >> 3 | ((src & 0xff) >> 3);
 				}
 				else
 					dest[u] = src;