engine: image: fix blue halo around sprays

common/com_image.h

@@ -116,6 +116,8 @@ typedef enum
 	IMAGE_MULTILAYER	= BIT(8),		// to differentiate from 3D texture
 	IMAGE_ONEBIT_ALPHA	= BIT(9),		// binary alpha
 	IMAGE_QUAKEPAL	= BIT(10),	// image has quake1 palette
+	IMAGE_PREMULTIPLIED	= BIT(11),
+	IMAGE_PLAYERDECAL	= BIT(12),	// loaded with IL_LOAD_PLAYER_DECAL (custom player spray)
 
 	// Image_Process manipulation flags
 	IMAGE_FLIP_X	= BIT(16),	// flip the image by width

common/render_api.h

@@ -101,7 +101,7 @@ typedef enum
 	TF_TEXTURE_3D	= (1<<20),	// this is GL_TEXTURE_3D
 	TF_ATLAS_PAGE	= (1<<21),	// bit who indicate lightmap page or deluxemap page
 	TF_ALPHACONTRAST	= (1<<22),	// special texture mode for A2C
-// reserved
+	TF_PREMULTIPLIED	= (1<<23),	// RGBA was stored premultiplied (HL gradient / indexalpha)
 // reserved
 	TF_IMG_UPLOADED	= (1<<25),	// this is set for first time when called glTexImage, otherwise it will be call glTexSubImage
 	TF_ARB_FLOAT	= (1<<26),	// float textures

engine/common/imagelib/img_main.c

@@ -173,6 +173,9 @@ static MALLOC_LIKE( FS_FreeImage, 1 ) rgbdata_t *ImagePack( const char *name )
 
 	Image_ReportLookupsCount( name );
 
+	if( Image_CheckFlag( IL_LOAD_PLAYER_DECAL ))
+		SetBits( image.flags, IMAGE_PLAYERDECAL );
+
 	// clear any force flags
 	image.force_flags = 0;
 

engine/common/imagelib/img_wad.c

@@ -250,6 +250,8 @@ qboolean Image_LoadSPR( const char *name, const byte *buffer, fs_offset_t filesi
 		SetBits( image.flags, IMAGE_ONEBIT_ALPHA );
 		// intentionally fallthrough
 	case LUMP_GRADIENT:
+		SetBits( image.flags, IMAGE_HAS_ALPHA );
+		break;
 	case LUMP_QUAKE1:
 		SetBits( image.flags, IMAGE_HAS_ALPHA );
 		break;

ref/gl/gl_decals.c

@@ -868,6 +868,10 @@ void DrawSingleDecal( decal_t *pDecal, msurface_t *fa )
 
 	GL_Bind( XASH_TEXTURE0, pDecal->texture );
 
+	if( FBitSet( R_GetTexture( pDecal->texture )->flags, TF_PREMULTIPLIED ))
+		pglBlendFunc( GL_ONE, GL_ONE_MINUS_SRC_ALPHA );
+	else pglBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
+
 	pglBegin( GL_POLYGON );
 
 	for( i = 0; i < numVerts; i++, v += VERTEXSIZE )

ref/gl/gl_image.c

@@ -1238,6 +1238,8 @@ static void GL_ProcessImage( gl_texture_t *tex, rgbdata_t *pic )
 	// force upload texture as RGB or RGBA (detail textures requires this)
 	if( tex->flags & TF_FORCE_COLOR ) pic->flags |= IMAGE_HAS_COLOR;
 	if( pic->flags & IMAGE_HAS_ALPHA ) tex->flags |= TF_HAS_ALPHA;
+	if( FBitSet( pic->flags, IMAGE_PREMULTIPLIED ))
+		SetBits( tex->flags, TF_PREMULTIPLIED );
 
 	tex->encode = pic->encode; // share encode method
 
@@ -1275,6 +1277,23 @@ static void GL_ProcessImage( gl_texture_t *tex, rgbdata_t *pic )
 		// processing image before uploading (force to rgba, make luma etc)
 		if( pic->buffer ) gEngfuncs.Image_Process( &pic, 0, 0, img_flags, 0 );
 
+		if( FBitSet( pic->flags, IMAGE_PLAYERDECAL ) && pic->buffer && pic->type == PF_RGBA_32 && FBitSet( pic->flags, IMAGE_HAS_ALPHA )
+		    && !FBitSet( pic->flags, IMAGE_PREMULTIPLIED ))
+		{
+			int	i, cnt = (int)( pic->width * pic->height );
+			byte	*p = pic->buffer;
+
+			for( i = 0; i < cnt; i++, p += 4 )
+			{
+				int	a = p[3];
+				p[0] = ( p[0] * a + 127 ) / 255;
+				p[1] = ( p[1] * a + 127 ) / 255;
+				p[2] = ( p[2] * a + 127 ) / 255;
+			}
+			SetBits( pic->flags, IMAGE_PREMULTIPLIED );
+			SetBits( tex->flags, TF_PREMULTIPLIED );
+		}
+
 		if( FBitSet( tex->flags, TF_LUMINANCE ))
 			ClearBits( pic->flags, IMAGE_HAS_COLOR );
 	}

ref/gl/gl_rsurf.c

@@ -2775,7 +2775,9 @@ static void R_DrawDlightedDecals( vboarray_t *vbo, msurface_t *newsurf, msurface
 				if( glt->fogParams[3] > 230 )
 					pglTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
 				else pglTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE );
-				pglBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
+				if( FBitSet( glt->flags, TF_PREMULTIPLIED ))
+					pglBlendFunc( GL_ONE, GL_ONE_MINUS_SRC_ALPHA );
+				else pglBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
 			}
 			else
 			{
@@ -3197,7 +3199,9 @@ static void R_DrawStaticDecals( vboarray_t *vbo, qboolean drawlightmap, int ilig
 				if( glt->fogParams[3] > 230 )
 					pglTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
 				else pglTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE );
-				pglBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
+				if( FBitSet( glt->flags, TF_PREMULTIPLIED ))
+					pglBlendFunc( GL_ONE, GL_ONE_MINUS_SRC_ALPHA );
+				else pglBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
 			}
 			else
 			{