@SideOnly(Side.CLIENT)
public interface IBlockColor
{
int colorMultiplier(IBlockState state, @Nullable IBlockAccess worldIn, @Nullable BlockPos pos, int tintIndex);
}
The method takes an IBlockState, an IBlockAccess, a BlockPos, and an int. I'm going to set the tintIndex to 0, since that corresponds with the json files. As for the other three, I'm probably going to want the IBlockState, IBlockAccess, and BlockPos for all blocks that need to be coloured (canvas blocks in this case)