imagelib: check flags for DDS and KTX2 support

- Checks for `IL_DDS_HARDWARE` support for compressed formats in KTX2
- Checks for `IL_KTX2_RAW` before providing raw KTX2 data

common/com_image.h

@@ -69,6 +69,7 @@ typedef enum
 	IL_LOAD_DECAL	= BIT(5),	// special mode for load gradient decals
 	IL_OVERVIEW	= BIT(6),	// overview required some unque operations
 	IL_LOAD_PLAYER_DECAL = BIT(7), // special mode for player decals
+	IL_KTX2_RAW = BIT(8), // renderer can consume raw KTX2 files (e.g. ref_vk)
 } ilFlags_t;
 
 // goes into rgbdata_t->encode

engine/common/imagelib/img_ktx2.c

@@ -114,6 +114,11 @@ static qboolean Image_KTX2Parse( const ktx2_header_t *header, const byte *buffer
 		return false;
 	}
 
+	if( !Image_CheckFlag( IL_DDS_HARDWARE ) && ImageCompressed( image.type )) {
+		Con_DPrintf(S_WARN "%s: has compressed format, but support is not advertized\n", __FUNCTION__);
+		return false;
+	}
+
 	if (header->pixelDepth > 1) {
 		Con_DPrintf(S_ERROR "%s: unsupported KTX2 pixelDepth %d\n", __FUNCTION__, header->pixelDepth);
 		return false;
@@ -197,6 +202,9 @@ qboolean Image_LoadKTX2( const char *name, const byte *buffer, fs_offset_t files
 	image.num_mips = 1;
 
 	if (!Image_KTX2Parse(&header, buffer, filesize)) {
+		if (!Image_CheckFlag( IL_KTX2_RAW ))
+			return false;
+
 		// If KTX2 to imagelib conversion failed, try passing the file as raw data.
 		// This is useful for ref_vk which can directly support hundreds of formats which we don't convert to pixformat_t here
 

ref/vk/vk_textures.c

@@ -52,7 +52,7 @@ void initTextures( void ) {
 	vk_numTextures = 0;
 
 	// TODO really check device caps for this
-	gEngine.Image_AddCmdFlags( IL_DDS_HARDWARE );
+	gEngine.Image_AddCmdFlags( IL_DDS_HARDWARE | IL_KTX2_RAW );
 
 	tglob.default_sampler_fixme = pickSamplerForFlags(0);
 	ASSERT(tglob.default_sampler_fixme != VK_NULL_HANDLE);