I've been exploring code for the last 4 hours and I can't find a way to make that work. 

 

Also tried the search on the forums but couldn't come up with better keywords, I'm afraid.

 

Is it possible to get the "NORTH; EAST; WEST; UP; DOWN; SOUTH" side  of a block corresponding to the player crosshair?

 

I want to call it inside of onItemUse, or onItemUseFirst.

Pulled this from my code, use/edit freely

 

/**
 * If [4] is -1 , there was no block within reach.
 * @return [0]= BlockId, [1]= BlockX, [2]= BlockY, [3]= BlockZ, [4]= SideHit, [5]= BlockMeta
 */
public static int[] getBlockInfront(World theWorld, EntityPlayer thePlayer, double reach)
{
	int[] blockInfo = { 0, 0, 0, 0, -1, 0 };

	MovingObjectPosition movingobjectposition = getMovingObjectPositionFromPlayer(theWorld, thePlayer, true, reach);
	if (movingobjectposition != null) {
		if (movingobjectposition.typeOfHit == EnumMovingObjectType.TILE) {
			blockInfo[1] = movingobjectposition.blockX;
			blockInfo[2] = movingobjectposition.blockY;
			blockInfo[3] = movingobjectposition.blockZ;
			blockInfo[4] = movingobjectposition.sideHit;
			blockInfo[5] = theWorld.getBlockMetadata(blockInfo[1], blockInfo[2], blockInfo[3]);
			blockInfo[0] = theWorld.getBlockId(blockInfo[1], blockInfo[2], blockInfo[3]);
		}
	}
	return blockInfo;
}

private static MovingObjectPosition getMovingObjectPositionFromPlayer(World world, EntityPlayer entityplayer, boolean flag, double reach)
{
	float f = 1.0F;
	float playerPitch = entityplayer.prevRotationPitch + (entityplayer.rotationPitch - entityplayer.prevRotationPitch) * f;
	float playerYaw = entityplayer.prevRotationYaw + (entityplayer.rotationYaw - entityplayer.prevRotationYaw) * f;
	double playerPosX = entityplayer.prevPosX + (entityplayer.posX - entityplayer.prevPosX) * f;
	double playerPosY = (entityplayer.prevPosY + (entityplayer.posY - entityplayer.prevPosY) * f + 1.6200000000000001D) - entityplayer.yOffset;
	double playerPosZ = entityplayer.prevPosZ + (entityplayer.posZ - entityplayer.prevPosZ) * f;
	Vec3 vecPlayer = Vec3.createVectorHelper(playerPosX, playerPosY, playerPosZ);
	float cosYaw = MathHelper.cos(-playerYaw * 0.01745329F - 3.141593F);
	float sinYaw = MathHelper.sin(-playerYaw * 0.01745329F - 3.141593F);
	float cosPitch = -MathHelper.cos(-playerPitch * 0.01745329F);
	float sinPitch = MathHelper.sin(-playerPitch * 0.01745329F);
	float pointX = sinYaw * cosPitch;
	float pointY = sinPitch;
	float pointZ = cosYaw * cosPitch;
	Vec3 vecPoint = vecPlayer.addVector(pointX * reach, pointY * reach, pointZ * reach);
	MovingObjectPosition movingobjectposition = world.rayTraceBlocks_do_do(vecPlayer, vecPoint, flag, !flag);
	return movingobjectposition;
}

Thank you very much friend